tag:blogger.com,1999:blog-46684058572911764692024-03-12T23:22:53.307-07:00chemistry notes / igcse-gcse- OlevelIda stanlyhttp://www.blogger.com/profile/17714974727845318262noreply@blogger.comBlogger65125tag:blogger.com,1999:blog-4668405857291176469.post-60583317133838765782009-11-27T08:10:00.000-08:002009-11-27T08:11:58.139-08:00collecting gases / igcse /gcse chemistry notesWe can collect gases in<br />4 ways :<br />1- Downwards into a testube or a gas jar , this is used for gases which denser than air .<br />2- Upwards into a testube are a gas jar , this used to collect gases which less dense than air and are soluble in water .<br />3- Over water , - to collect gases which are less dense than air and are insoluble in water- or to collect gases which are having the same dense like air and are insoluble in water .<br />4- In a gas syringe , a gas syringe is used to collect the gas and to measure the volume of the gas collected .<br /><br />2- Normal test – pure water boils at 100 degrees CelsiusIda stanlyhttp://www.blogger.com/profile/17714974727845318262noreply@blogger.com0tag:blogger.com,1999:blog-4668405857291176469.post-51524528098146503552009-11-22T06:59:00.000-08:002009-11-22T07:01:19.962-08:00TITRATION OF UNKNOWN ACIDTitration of an Unknown (if done as per your instructor's directions)<br />1. Obtain an unknown solid and record its number.<br />2. Weigh out 0.1-0.2 g and place it in an Erlenmeyer flask.<br />3. Dissolve the acid in about 20 mL boiled distilled water.<br />4. Add two drops of the phenolphthalein indicator.<br />5. Titrate to the pale pink endpoint.6. Carry out at least two titrations; repeat until two consecutive values for equivalent weight of the acid differ by no more than 1%.Ida stanlyhttp://www.blogger.com/profile/17714974727845318262noreply@blogger.com0tag:blogger.com,1999:blog-4668405857291176469.post-30205674976646210962009-11-22T06:55:00.000-08:002009-11-22T06:59:36.611-08:00standardization ഓഫ് NaoHStandardization of NaOH1.<br />Clean a buret and rinse it with the NaOHyou just prepared.<br />2. Fill the buret with the NaOH.<br />3. Weigh a clean dry beaker on a balance.<br />4. Weigh out 0.2 - 0.4 g of KHC8H4O4 and place it in the beaker you just weighed. Make sure you record the weights!<br />5. Pour the acid into an Erlenmeyer flask; use a stream of water from the wash bottle to complete the transfer.<br />6. Dissolve this acid in about 20 mL of the boiled distilled water.<br />7. Add two drops of the phenolphthalein indicator to the flask.<br />8. Read the buret and record the initial volume making sure there is not a drop on the tip of the buret; if there is, use an extra beaker to get rid of this drop by touching the side of the beaker to the tip of the buret.<br />9. Place the Erlenmeyer flask under the buret, and place a piece of white paper under it.<br />10. Position the tip of the buret so it is just beneath the rim of the flask.<br />11. Add several mL (probably no more than ten) of base solution (NaOH) rapidly with constant swirling.<br />12. Close buret stopcock to only allow a rapid stream of drops and swirl; at the site where the solution in the buret drops in the acid solution, you will see a pink color, which will disappear<br /><br />13. When the pink color lingers longer, close the stopcock on the buret more so that you add a drop and swirl until the color changes before adding another drop.<br />14. Occasionally wash down the sides of the flask with the wash bottle.<br />15. Near the end point you will want to use partial drops. To do this, open the stopcock so that a drop forms on the tip of the buret. Close the stopcock and use a stream of water from the water bottle to wash the droplet into the sol.<a href="http://capital2.capital.edu/faculty/wbecktel/movie1.mov"></a><br />16. Keep adding base until a very light pink color persists for at least 20 seconds. <a href="http://capital2.capital.edu/faculty/cney/101L/ENDPT.JPG"></a><a href="http://capital2.capital.edu/faculty/cney/101L/ENDPT.JPG"></a><br />17. Record the final buret reading.18. Repeat this procedure at least two more times; repeat the titrations until two values for molarity differ by no more than 1% C.Ida stanlyhttp://www.blogger.com/profile/17714974727845318262noreply@blogger.com0tag:blogger.com,1999:blog-4668405857291176469.post-4255975534668174602009-11-18T04:39:00.000-08:002009-11-18T04:42:48.008-08:00Metallic bonding work sheet IGCSE1. DESCRIBE METTALIC BONDING<br />2. WHY METALS ARE MALLIABLE?<br />3. DEFINE ALLOYS? GIVE EX .<br />4. WHY ALLOYS ARE HARD IN NATURE?Ida stanlyhttp://www.blogger.com/profile/17714974727845318262noreply@blogger.com0tag:blogger.com,1999:blog-4668405857291176469.post-60059840467397623022009-11-18T04:33:00.000-08:002009-11-18T04:37:29.181-08:00IONIC BONDING / WORK SHEET / IGCSE / GCSE / CHEMISTRY1.Draw the dot and cross diagram dor the following<br />Calcium oxide<br />Magnesiumm chloride<br />Lithum chloride<br />2. Give the properties of ionic com pounds<br />3. sodium chloride conduct electricity in liquid state . why/<br />4. sodium chloride do not conduct electricity in solid state . why/Ida stanlyhttp://www.blogger.com/profile/17714974727845318262noreply@blogger.com0tag:blogger.com,1999:blog-4668405857291176469.post-80411279660435474712009-11-18T04:20:00.000-08:002009-11-18T04:21:37.387-08:00The Noble Gases- igcse / gcse/ o level1.What is the Group Number of the Noble Gases?<br />2.What does Monatomic mean?<br />3.Going down the Group, do the Noble Gases have a Higher Boiling Point?<br />4.Give one Use of Helium?<br />5.Give one Use of Neon?<br />6.Give one Use of Argon?Ida stanlyhttp://www.blogger.com/profile/17714974727845318262noreply@blogger.com0tag:blogger.com,1999:blog-4668405857291176469.post-58098371793340924682009-11-18T04:17:00.000-08:002009-11-18T04:19:43.510-08:00The Halogens- igcse/ gcse/ o levelThe Halogens- igcse/ gcse/ o level<br />1.What is the Group Number of the Halogens?<br /> 2.What does Diatomic mean? 37.What Colour is Chlorine?<br />3.What Colour is Bromine?<br /> 4.Is Iodine a Liquid?<br /> 5.Going down the Group, do the Halogens become More Reactive?<br /> 6.Going down the Group, do the Halogens have a Higher Boiling Point?<br /> 7.Write the Balanced Equation for the reaction between Aluminium and Chlorine.<br /> 8.Write the Balanced Equation for the reaction of Chlorine with Potassium Iodide.<br /> 9.Write the Ionic Equation for the reaction of Chlorine with Potassium Iodide.<br /> 10.Give one Use of Fluoride?<br />11.Give one Use of Chlorine? 47Give one Use of Bromide?<br />12.What does Hydrogen Chloride make when it is Dissolved in Water?<br /> 13.How is Hydrogen Chloride Safely Dissolved in Water?Ida stanlyhttp://www.blogger.com/profile/17714974727845318262noreply@blogger.com0tag:blogger.com,1999:blog-4668405857291176469.post-62156915793175484432009-11-18T04:16:00.000-08:002009-11-18T04:17:04.863-08:00The Transition Metals- igcse/ gcse/olevel1.Where do you find the Transition Metals in the Periodic Table?<br />2.What is their Group Number?<br />3.Do the Transition Metals Conduct Electricity?<br />4.Do the Transition Metals form Coloured Compounds?<br />5.Give one Use of Copper?<br />6.Give one Example of a Transition Metal Used as a Catalyst.Ida stanlyhttp://www.blogger.com/profile/17714974727845318262noreply@blogger.com0tag:blogger.com,1999:blog-4668405857291176469.post-1299203591151456002009-11-18T04:12:00.000-08:002009-11-18T04:15:43.036-08:00Electrolysis of Sodium Chloride in Water1.What is Brine?<br />2.Which Gas is given off at the Cathode?<br /> 3.Which Gas is given off at the Anode?<br />4.Give the Ionic Equation for the Gas given off at the Anode.<br />5Why don't you get Sodium Metal at the Cathode?<br />6.What Substance is left in Solution after Electrolysis?<br />7.Give one Use of this Substance?Ida stanlyhttp://www.blogger.com/profile/17714974727845318262noreply@blogger.com0tag:blogger.com,1999:blog-4668405857291176469.post-53463730111230211162009-11-18T04:09:00.000-08:002009-11-18T04:12:35.453-08:00The Alkali Metals- igcse/ gcse /olevel1.What is the Group Number of the Alkali Metals?<br /><br />2.Why are the Alkali Metals stored under oil?<br /><br />3.Give two Properties of the Alkali Metals?<br /><br />4.Going down the Group, do the Alkali Metals become More Reactive?<br /><br />5.Write the Word Equation for the reaction when Potassium burns in Air.<br /><br />6.What Colour is the Flame from Potassium?<br /><br />7.Write the Balanced Equation for the reaction when Potassium burns in Air.<br /><br />8.Write the Balanced Equation for the reaction between Sodium and Water.<br /><br />9.Write two things you would See in the reaction between Sodium and Water.<br /><br />10.Write the Balanced Equation for the reaction between Lithium and Chlorine.<br /><br />11.Give one Property of an Alkali Metal Compound?<br /><br />12.Give one Use of Sodium Chloride?<br /><br />13.Give one Use of Sodium Carbonate?Ida stanlyhttp://www.blogger.com/profile/17714974727845318262noreply@blogger.com0tag:blogger.com,1999:blog-4668405857291176469.post-73478153686518698382009-11-18T03:58:00.000-08:002009-11-22T06:53:38.081-08:00Preparation of NaOH solutionInstructionsA.<br /> Preparation of NaOH സോലുറേന്<br />1. Measure about 500 mL of distilled water and boil it for about five minutes.<br />2. Allow the beaker to cool enough so you can pick it up with a towel.<br />3. Using a graduated cylinder, measure 290 mL of this water into a large flask.<br />4. Add 10 mL of 3M NaOH to this water.CAUTION! NaOH IS CORROSIVE!!!!!!! If you spill any on yourself, wash it off immediately!!!!5. Stopper the flask, making sure not to let the stopper come in contact with the solution.6. Swirl the flask to mix the NaOH and water.7. Pour the rest of the water you boiled into a wash bottle. You can use this later to dissolve the acid sample and wash down the sides of the flask during the titration.B.Ida stanlyhttp://www.blogger.com/profile/17714974727845318262noreply@blogger.com0tag:blogger.com,1999:blog-4668405857291176469.post-23847234479629354022009-04-09T03:21:00.001-07:002009-11-17T01:13:11.797-08:00alcohols<div align="justify">Alcohols make good fuels because they burn easily and they release a lot of heat energy, which can be harnessed to power machines etc...<br /><br />The combustion of alcohol is an exothermic reaction and this means that heat is given out from the reaction, opposed to being taken in, which would occur in an endothermic reaction. The following equation shows the result of combustion of alcohol (in this case, ethanol).<br /><br />Alcohol + Oxygen ----> Carbon Dioxide + Water<br /><br />C2H5OH + 3O2 ----> 2CO2 + 3H2O<br /><br />The general formula for alcohols is as follows:<br />CnH2n+1OH (where "n" is a constant) The Alcohols form a homologous series where they all have similar chemical structures and properties. They are produced from either anaerobic respiration or by reacting water with the alkenes (Hydration).<br /><br /><br />The first five members of this homologous series are:<br /><br />CH3OH (Methanol)C2H5OH (Ethanol)C3H7OH (Propanol)C4H9OH (Butanol)C5H11OH (Pentanol)</div>Ida stanlyhttp://www.blogger.com/profile/17714974727845318262noreply@blogger.com0tag:blogger.com,1999:blog-4668405857291176469.post-35283751201107357502009-04-09T03:18:00.000-07:002009-11-22T07:04:54.132-08:00contact process- IGCSE/GCSE NOTES<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiGtpt_AHeMFW8WtcMFsZcHTf-J7Kz1WpmHpwikT0CPmWSULKF2v_bAPnKpL4l2ThXgtZEuc2dNo9s-OkylmypQDQW4ZHFHEfwg4rUp7YtubBpY7aLj5VzrmENdCCcBTa33I0Sf86WqXYom/s1600-h/contact_process.gif"><img id="BLOGGER_PHOTO_ID_5322634360701377202" style="FLOAT: right; MARGIN: 0px 0px 10px 10px; WIDTH: 396px; CURSOR: hand; HEIGHT: 400px" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiGtpt_AHeMFW8WtcMFsZcHTf-J7Kz1WpmHpwikT0CPmWSULKF2v_bAPnKpL4l2ThXgtZEuc2dNo9s-OkylmypQDQW4ZHFHEfwg4rUp7YtubBpY7aLj5VzrmENdCCcBTa33I0Sf86WqXYom/s400/contact_process.gif" border="0" /></a><br /><div>The contact process is the name given to the process by which sulphuric acid is produced. Sulphuric acid has many uses such as the manufacturing of:<br />Paints / Pigments<br />Soaps / Detergents<br />Fibres<br />Plastics<br />Fertilisers The following reactions are involved:<br />S (s) + O2 (g) ----> SO2 (g) (sulphur dioxide)<br />2SO2 (g) + O2 (g) ----> 2SO3 (g) (sulphur trioxide) </div>Ida stanlyhttp://www.blogger.com/profile/17714974727845318262noreply@blogger.com0tag:blogger.com,1999:blog-4668405857291176469.post-15700664852028818202009-04-09T03:09:00.001-07:002009-04-09T03:09:44.534-07:00work sheet - balancing equations. _____Zn + _____HCl --> _____ZnCl2 + _____H2<br />2. _____NH3 + _____HCl --> _____NH4Cl<br />3. _____Al + _____HCl --> _____AlCl3 + _____H2<br />4. _____Mg + _____H3PO4 --> _____Mg3(PO4)2 + _____H2<br />5. _____Cu + _____AgNO3 --> _____Cu(NO3)2 + _____Ag<br />6. _____Ca + _____Pb(NO3)2 --> _____Pb + _____Ca(NO3)2<br />7. _____Al + _____Pb(NO3)2 --> _____Pb + _____Al(NO3)3<br />8. _____Zn + _____Sn(NO3)4 --> _____Zn(NO3)2 + _____Sn<br />9. _____Cl2 + _____AlI3 --> _____AlCl3 + _____I2<br />10. _____Br2 + _____CuI --> _____CuBr + _____I2<br />11. _____NH4OH + _____FeCl3 --> _____NH4Cl + _____Fe(OH)3<br />12. _____KBr + _____Pb(NO3)2 --> _____KNO3 + _____PbBr2<br />13. _____AlCl3 + _____H2SO4 --> _____Al2(SO4)3 + _____HCl<br />14. _____Al2(SO4)3 + _____BaCl2 --> _____BaSO4 + _____AlCl3<br />15. _____Na2CO3 + _____CaCl2 --> _____CaCO3 + _____NaClIda stanlyhttp://www.blogger.com/profile/17714974727845318262noreply@blogger.com0tag:blogger.com,1999:blog-4668405857291176469.post-88503534225976171402009-01-09T11:13:00.000-08:002009-11-18T03:58:00.899-08:00AS level chemistry practical (GCE)<div align="left"><strong>Chemistry 101 Laboratory<br /></strong><a name="Experiment"></a><strong>Experiment 10: Acid/ Base Titrations<br /></strong><a name="Pre-Laboratory"></a><strong>Pre-Laboratory<br /></strong><a name="Pre-lab"></a><strong>Pre-lab Questions<br />1. How would your calculated molarity of NaOH be affected by each of the following errors? Elaborate. </strong></div><strong><div align="left"><br />a.) The buret is not rinsed with solution before filling.</div><div align="left">b.) Some solution splashes out of the flask during titration.</div><div align="left">c.) You go past the end point in the titration.<br />2. How would your calculated value for the equivalent weight of the acid be affected by each of the following errors? Elaborate.<br />a.) Some acid is spilled out of the flask after it is weighed. </div><div align="left">b.) Some solution splashes out of the flask during titration. </div><div align="left">c.) You go past the end point of the titration.<br />3. What is the effect of allowing a solution of NaOH to remain in contact with the air in the laboratory? Be specific as to the two, main effects and their sources.<br /></strong><a name="Laboratory"></a><strong>Laboratory<br />The reaction of an acid and a base in water involves the reaction of hydroxide and hydrogen ions to form water (neutralization) and the formation of the resulting salt from the conjugate base and acid. The latter may or may not be soluable. </strong></div><div align="left"><strong>In general, the reaction is given by the following reaction for simple acids and bases:<br />HA + HOX <-> H2O + A- + X+<br />In this example, just one hydrogen and one hydroxl ion were available for the reaction. The ionization of the acid therefore produces one "equivalent" (one mole per mole) of hydrogen ions and ionization of the base produces one equivalent of hydroxyl ions. ( It is important to remember that, in water, the hydrogen ion and hydroxyl ion are the strongest acid and base, respectively. For this reason, ionization of any acid or base in water leads to the production of soley these acidic and basic ions.) </strong></div><div align="left"><strong>It is possible that one mole of the acid or base will produce more than one mole (one equivalent mole) of hydrogen ions or hydroxyl ions. An example of this is the diprotic acid sulfuric H2SO4. </strong></div><div align="left"><strong>In this instance, a total of 2 moles of hydrogen ions are produced when the acid is completely ionized to the sulfate.<br />When a titration is carried out, an acid or base of unknown concentration is allowed to neutralize a base or acid known to produce a known number of moles of hydroxyl or hydrogen ions. </strong></div><div align="left"><strong>As the acid or base is added to the solution of a known number of moles, the acids and bases react to neutralize one another. </strong></div><div align="left"><strong>At the point where the number of moles of acid equals the number of moles of base, we have reached what is called equivalence. </strong></div><div align="left"><strong>This is also known as the equivalence point and is shown either by a indicating dye or pH meter.</strong></div><div align="left"><strong> At the equivalence point we know the number of moles of acid or base reacted (from the fact that we know the number of moles of base or acid originally present from the sample of known amount) and the number of liters of the unknown which were added to neutralize the solution.</strong></div><div align="left"><strong> From the definition of molarity we have the following relationship:<br />Equivalent molarity = (# moles originally )/ ( liters of unknown added)<br />Notice that this differs slightly from our usual definition of molarity. </strong></div><div align="left"><strong>The reason is that we have not taken into account the fact that our unknown acid or base may have more than one equivalent per mole. </strong></div><div align="left"><strong>In today's experiment, you will deal with a monoprotic acid and a simple hydroxyide (NaOH) so that the concentration you obtain will be the true molarity of the base.<br />One of the important concepts in any aspect of chemistry in which quantitative answers are required is that of the primary standard.</strong></div><div align="left"><strong> This is an agreed upon set of conditions, chemical compound, or anything else which is agreed to represent a measure to which other things are compared.</strong></div><div align="left"><strong> One such standard concerns hydrogen ion concentration and is the use of potassium hydrogen phthalate (KHC8H4O4, molecular weight 204.224) as a standard for the concentration of hydrogen ions in a solution.</strong></div><div align="left"><strong> One mole of this salt produces one mole of hydrogen ions in one liter of water.<br />A second thing which is required in the use of a primary standard is a means of knowing when all of the (in this case) hydrogen ions from the standard have been neutralized with the base.</strong></div><div align="left"><strong> One way of doing this is to use an indicator dye. </strong></div><div align="left"><strong>These are organic chemicals which are also weak acids and bases. On their ionization or protonation, they undergo a chemical change which also results in a change in color. </strong></div><div align="left"><strong>One such dye is phyenylphtalene, a close relative of the primary standard you are using. This dye is clear in acidic solutions, slightly pink in neutral pH solutions, and dark purple in basic solutions.</strong></div><div align="left"><strong> Addition of a small amount of the dye to the solution you are testing allows you to determine when an equivalent number of acids and bases were present.<br /></strong><a name="Instructions"></a></div><a href="http://capital2.capital.edu/faculty/wbecktel/101F8.html"></a><strong></strong>Ida stanlyhttp://www.blogger.com/profile/17714974727845318262noreply@blogger.com0tag:blogger.com,1999:blog-4668405857291176469.post-10850759787564758562009-01-09T11:09:00.000-08:002009-11-18T04:01:05.836-08:00AS level chemistry practical (GCE) Titration<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjSpu-z6t5c7Kdz4aVa4TyxQZWJjGcGTZGfqBD7wGLWMVZn6yGNvbuURCeEkM1XSlW5P560E79GMOFy7PcUWW2h4NgrU6f89XZUCuH_nFE1FnekXRUFvenY-qea5M6nPyki6ZowAIuhG8G3/s1600-h/smendpt.jpg"><img id="BLOGGER_PHOTO_ID_5289374123660420162" style="FLOAT: right; MARGIN: 0px 0px 10px 10px; WIDTH: 124px; CURSOR: hand; HEIGHT: 100px" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjSpu-z6t5c7Kdz4aVa4TyxQZWJjGcGTZGfqBD7wGLWMVZn6yGNvbuURCeEkM1XSlW5P560E79GMOFy7PcUWW2h4NgrU6f89XZUCuH_nFE1FnekXRUFvenY-qea5M6nPyki6ZowAIuhG8G3/s400/smendpt.jpg" border="0" /></a><br /><div></div><br /><div><strong>Titration</strong></div><br /><div><strong></strong></div><br /><div><strong>Titration that involve H2SO4 and NaOH is an examples of acid-base titration of a strong base acid and strong base, both the titrant and the analyte are completely ionized. The balanced reaction and its ionic reaction are:</strong></div><br /><div><strong></strong></div><br /><div><br /><strong>H2SO4 + 2NaOH -> Na2SO4 + 2H2OH+ + SO42- + 2 Na+ + 2OH- -> 2Na+ + SO42- + 2H2OH+ + + 2OH- -> H2O</strong></div><div><strong></strong></div><div><strong>The H+ combined with OH- to form H2O, and other ions (Na+ and SO42-) remain unchanged. </strong></div><div><strong>This is an example of neutralization reaction, the net result of this neutralization is conversion of H2SO4 into a neutral solution Na2SO4 in the equivalent point.</strong></div><div><strong>A titration curve is constructed by plotting the pH of the solution as a function of the volume of titrant added.</strong></div><div><strong></strong> </div><div><strong>The volume changes during titration must be employed for determining the concentrations of the species in the solutions (H+, OH- ). This is the example of the titration curve of 0.1 M H2SO4 100 mL versus 0.1 M of NaOH.</strong><br /><strong>We began with 0.1 mL H2SO4 100 mL in Erlenmeyer flask and then 0.1 mL of NaOH in the buret.</strong><br /><strong>At the start of the titration there is only H2SO4 in the solution so the pH of this solution is:<br />[H2SO4] = 0.1 M[H+] = 2 x 0.1 = 0.2 MpH = - log [H+] = -log(0.2) = 0.699</strong></div><div><br /><strong>as the titration begins, NaOH solution is added from the burette into the H2SO4 solution in the Erlenmeyer. </strong></div><br /><div><strong>The pH of the solution when the 20 mL NaOH 0.1 M is added to the solution is:<br />moles of H2SO4 = 0.1 M x 100 mL = 10 mmolmoles of NaOH = 0.1 M x 20 mL = 2 mmol</strong></div>Ida stanlyhttp://www.blogger.com/profile/17714974727845318262noreply@blogger.com0tag:blogger.com,1999:blog-4668405857291176469.post-80306875046160178322009-01-09T10:58:00.000-08:002009-11-18T04:02:02.894-08:00AS level chemistry practical (GCE)<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhsUb-y6xVH_EX_TQ24u3Nqmo3T5UFKERN3Ynth3OYa36G90FflL8vCV4xbYtGk8s8d-MEQ24Ogh7i4TAfu-hYEYBuWI2iLK4m6aN1RuVd1aq7jylD-LkSRHZfLttleE796RzBYeqTCqGlQ/s1600-h/Chem_img029.jpg"><img id="BLOGGER_PHOTO_ID_5289371436562582194" style="FLOAT: right; MARGIN: 0px 0px 10px 10px; WIDTH: 300px; CURSOR: hand; HEIGHT: 400px" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhsUb-y6xVH_EX_TQ24u3Nqmo3T5UFKERN3Ynth3OYa36G90FflL8vCV4xbYtGk8s8d-MEQ24Ogh7i4TAfu-hYEYBuWI2iLK4m6aN1RuVd1aq7jylD-LkSRHZfLttleE796RzBYeqTCqGlQ/s400/Chem_img029.jpg" border="0" /></a><br /><div><strong>A level chemistry practicals( GCE)<br />1. Titration -Acid base titration – Hcl AND NaOH<br />Purpose:</strong></div><div><strong></strong></div><div><strong>To determine the molarity of an unknown acid solution by titration using phenolphthalein as an indicator. </strong></div><div><strong></strong></div><div><strong>Materials: </strong></div><div><strong>Burets<br />Clamp<br />Stand<br />Beakers<br />1M HCl solution<br />1M NaOH solution<br />Unknown HCl solution<br />Phenolphthalein indicator solution </strong></div><div><strong>Procedure: </strong></div><div><strong>Clean and dry the burets and beaker, and clamp the two burets to the ring stand. Fill one of the two burets with 1M HCl solution, and the other with the NaOH solution.<br />Use the buret to measure out 20 mL of HCl into an empty beaker. Add 2-3 drops of the indicator solution. </strong><br /><strong>Titrate slowly with the NaOH solution, with constant swirling, until one single drop of NaOH causes a permanent pink color that does not fade onswirling. Record the volume of NaOH used.<br />Use the formula M1V1=M2V2 to determine the concentration of the NaOH solution. This solution may now be used to titrate the unknown acid sample. </strong><br /><strong>Replace the buret containing the 1M HCl with the buret containing the HCl solution of unknown concentration. Refill the NaOH buret, and wash out the beaker.<br />Repeat the titration from steps 2-4 using 20 mL of the unknown acid solution to determine the concentration of the HCl solution.<br /><br /></strong></div>Ida stanlyhttp://www.blogger.com/profile/17714974727845318262noreply@blogger.com0tag:blogger.com,1999:blog-4668405857291176469.post-83306149339461104252008-12-12T04:44:00.000-08:002009-11-18T04:09:22.155-08:00revision work sheet- Periodic Table1<strong>.Why did Dmitri Mendeleev leave gaps in his Periodic Table?
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<br />2.What is a Column called?
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<br />3.What is a Row called?
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<br />4.Where do you find Non-Metals in the Periodic Table?
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<br />5.What is important about the Group Number of an Element?
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<br />6.What is the Electron Structure of Potassium?
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<br />Ida stanlyhttp://www.blogger.com/profile/17714974727845318262noreply@blogger.com0tag:blogger.com,1999:blog-4668405857291176469.post-35874206902691951372008-12-12T04:27:00.000-08:002009-11-18T04:29:12.808-08:00ATOMIC STRUCTURE igcse -chemistry / revision work ഷീറ്റ്<p><strong></strong> </p><p><strong>1.What is an Atom?<br />2.Which Particles are found in the Nucleus?</strong><br /><strong>3.What is the charge on an Electron?</strong><br /><strong>4.What is the charge on a Neutron?</strong><br /><strong>5.Does a Proton have more mass than a Neutron?</strong><br /><strong>6.Does a Proton have more mass than an Electron?</strong><br /><strong>7.What is the Atomic Number</strong>?<br /><strong>8.What is an Isotope?</strong><br /><strong>9.What is the maximum number of Electrons in each Shell?</strong><br /><strong></strong><br /></p><div align="center"> </div>Ida stanlyhttp://www.blogger.com/profile/17714974727845318262noreply@blogger.com0tag:blogger.com,1999:blog-4668405857291176469.post-58095435950948864672008-11-27T06:46:00.000-08:002008-12-14T22:04:34.754-08:00Making metals useful-gcse chemistry<strong>Making metals useful </strong>
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<br />The reactivity of aluminium and anodisingAluminium is high in the reactivity series but does not corrode in air or water.</strong>
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<br /><strong>The reason is that aluminium covers itself with a thin layer of aluminium oxide which protects it from further corrosion.</strong>
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<br /><strong>Anodising is the industrial process of coating aluminium objects with a thicker layer of aluminium oxide.</strong>
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<br /><strong>The aluminium object forms the anode (positive electrode) in a sulfuric acid electrolyte during electrolysis. </strong>
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<br /><strong>Oxygen atoms form at the anode and join with the aluminium. This is oxidation.</strong>
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<br /><strong>Draw a labelled diagram for apparatus suitable for anodising an aluminium rod. </strong>
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<br /><strong>Show the electrodes, the electrolyte, and the cell.</strong>
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<br /><strong>Explain duralumin use in aircraft instead of aluminium. </strong>
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<br /><strong>Explain magnalium use in window frames instead of aluminium.</strong>
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<br /><strong>Important uses of aluminium and its alloys
<br />metal or alloy </strong>
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<br />aluminium -overhead power cables
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<br />good electrical conductor, low density
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<br />aluminium -drinks cans -Does not react with water
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<br />aluminium -cooking pots -good heat conductor
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<br />duralumin -aircraft and bicycle parts -high strength, low density and hard
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<br />magnalium -aircraft parts -high strength, low density and corrosionresistance</strong>
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<br /><strong>Chemical reactions in different parts of the blast furnace (high tier)Iron is made in the blast furnace.</strong>
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<br /><strong>Write equations for each of the reactions in the blast furnace.</strong>
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<br /><strong>The limited uses of pure iron and impure iron from the blast furnaceImpure iron from the blast furnace (only 93% pure) is called cast iron.</strong></p><p><strong>Pure or wrought iron is not now mass produced but is still available. </strong>
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<br /><strong>cast iron
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<br />brittle, high compression strength </strong><strong>
<br />car engine blocks, man hole covers, gas stoves. </p><p>
<br />wrought iron
<br />soft, bends easily, easily worked, low corrosion
<br />nails, bolts, chains, garden gates, decorative ironwork</strong>
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<br /><strong>The production of mild steelIron from the blast furnace contains impurities like carbon, sulfur, silicon and phosphorus.</strong></p><p><strong> These are removed in the basic oxygen process. In this process a water cooled lance is put into impure molten iron and pure oxygen is blown through it.</strong></p><p><strong> The impurities are changed to oxides which come out as gases such carbon dioxide, and sulfur dioxide.</strong></p><p><strong> Solid oxides formed react with added calcium oxide to form a slag which floats on top of the iron. </strong></p><p><strong>When the amount of carbon drops to about 1 or 2% the process is stopped and the result is called mild steel.</strong>
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<br /><strong>The uses of mild steelMild steel containing a small amount of carbon eg 0.5% is has the hardness and strength for making machines, rails, ship's plates and girders for bridges and buildings.</strong></p><p><strong> The uses of alloy steelsThe properties of steels can be controlled by carefully changing the amounts of carbon removed and amounts of other metals put into them.
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<br /></p></strong>Ida stanlyhttp://www.blogger.com/profile/17714974727845318262noreply@blogger.com0tag:blogger.com,1999:blog-4668405857291176469.post-32014020660514501092008-11-27T06:34:00.000-08:002008-12-14T22:05:15.106-08:00Quantitative chemistry( chemical calculation)-IGCSE/GCSE<strong>Avogadro’s Law and use it to </strong><br /><strong></strong><br /><strong>calculate volumes of gases in reactionsAvogadro's law states that equal volumes of gases measured at the same temperature and pressure contain equal numbers of molecules.</strong><br /><strong></strong><br /><strong>The numbers of molecules shown in a chemical equation give the ratio of volumes of reacting gases. e.g. if steam is made the equation is:2H2(g) +O2(g) ---> 2H2O(g)</strong><br /><strong></strong><br /><strong>This means that 2 molecules of hydrogen react with 1 molecule of oxygen to form 2 molecules of steam.So 2dm3 of hydrogen reacts with 1 dm3 of oxygen and form 2dm3 of steam.</strong><br /><strong></strong><br /><strong>Or 4dm3 of hydrogen reacts with 2dm3 of oxygen and form 4dm3 of steam etc.volume of H2(g)/ volume of O2(g)= molecules of H2(g)/ molecules of O2(g)Write two other equations linking volumes and molecules in the above equation.</strong><br /><strong></strong><br /><strong>Calculate the volume of steam formed if 10cm3 of hydrogen is burned in oxygen.volume of steam/volume of hydrogen = molecules of steam/molecules of hydrogenvolume of steam= volume of hydrogen * molecules of steam/molecules of hydrogenvolume of steam = 10cm3 * 2/2 = 10cm3</strong><br /><strong></strong><br /><strong>Calculate the volume of steam formed if 10cm3 of oxygen is used to burn hydrogen.Calculate the volume of HCl gas formed if 2dm3 of hydrogen is burned in chlorine.</strong><br /><strong></strong><br /><strong>What volume of hydrogen and nitrogen is needed to make 30dm3 of ammonia by the equationN2 (g) + 3H2 (g)= 2NH3(g) </strong><br /><strong></strong><br /><strong>When ammonia is oxidised by oxygen what volume of NO and steam is formed by 25cm3 of ammonia? 4NH3(g) + 5O2(g) = 4NO(g) + 6H2O(g)</strong><br /><strong></strong><br /><strong>The chemical amount represents a number of particles.</strong><br /><strong></strong><br /><strong></strong><br /><strong> One mole is a special very large number called the Avogadro number. It is 6*1023. We cannot count particles but can weigh substances. The molar mass is the mass of one mole of particles e.g. atoms, of a substance. </strong><br /><strong>The molar mass of an element made of atoms is the relative atomic mass of the element in grams. </strong><br /><strong>The molar mass of a compound of element made of molecules is the relative molecular mass or relative formula mass of that substance in grams. </strong><br /><strong></strong><br /><strong></strong><br /><strong>These 3 quantities are connected:amount = mass/molar masse.g</strong><br /><strong></strong><br /><strong> What amount of methane molecule CH4 is there is 4g of methane?C=12 H=1 so molar mass of methane = 12 + (4*1) = 16g/molAmount = mass/molar mass = 4g/16g/mol = 0.25mol</strong><br /><strong></strong><br /><strong>What are the molar masses of the following; He, Na, Cl, Cl2, O2, N, FeS, MgO, KF, HCl, H2O, NH3, NaOH, HNO3, H2SO4, Ca(OH)2.</strong><br /><strong></strong><br /><strong>What amounts are the following masses; 2g of H, 2g of He, 7g of Cl2, 11.2g of FeS, 73g of HCl, 8g of NaOH, 25g of CaCO3.</strong><br /><strong></strong><br /><strong>What is the mass of: 1 mol of Li, 2 mol of C, 3 mol of S, 1 mol of O2, 1 mol of O3, 1 mol of NaCl, 0.1 mol of NH3, 0.5 mol of H2O, 0.2 mol of CaCO3.C7.22 </strong><br /><strong></strong><br /><strong>Calculating the volume of a given mass of gas and vice versaThe volume of one mole of any gas is a constant known as the molar volume.At room temperature and pressure it is 24dm3/mol.amount of gas molecules = volume of gas/molar volumee.g. </strong><br /><strong></strong><br /><strong>What is the mass of 6dm3 of hydrogen H2 at room temperature and pressure if the molar volume under these conditions is 24dm3/mol?</strong><br /><strong></strong><br /><strong>H=1 so Molar mass of H2 = 1*2 = 2g/molamount of H2 = volume of H2/molar volume =6dm3/24dm3/mol =0.25molmass of H2 =amount of H2 * molar mass of H2 = 0.25mol*2g/mol = 0.5g</strong><br /><strong></strong><br /><strong></strong><br /><strong>What is the mass of: 24dm3 of He, 12dm3 of N2, 6dm3 of CO2, 4dm3 of O2, 3dm3 of F2, 48dm3 of SO2, 2dm3 of H2, 1dm3 of H2S.What is the volume of 1g of He, 2.8g of N2, 22g of CO2, 64g of O2, 19g of F2, 64g SO2, 0.5g H2, 0.34g of H2S. (assume that the molar volume is 24dm3 at room temp)</strong><br /><strong></strong><br /><strong></strong><br /><strong> Calculating reacting masses of substances or volumes of gasesA balanced chemical equation shows the amounts which react so masses or volumes of gases can be worked out from an equation. E.g. What mass of aluminium oxide can be made from 216g of aluminium and what volume of oxygen is needed?</strong><br /><strong></strong><br /><strong>Method 1 </strong><br /><strong></strong><br /><strong>4Al(s) + 3O2(g) ---> 2Al2O3(s)Al = 27, so relative formula mass of 4Al = 4*27 =108O = 16 so relative formula mass of 2Al2O3 = 2(27*2 + 16*3) = 204so 108g of aluminium forms 204g of aluminium oxideso 1g of aluminium forms 204/108g of aluminium oxideso 216g of aluminium forms 216*204/108g of aluminium oxideso 216g of aluminium forms 408g of aluminium oxide</strong><br /><strong></strong><br /><strong>Method 2</strong><br /><strong></strong><br /><strong>4Al(s) + 3O2(g) ---> 2Al2O3(s)mass of Al = 216gamount of Al = mass/molar mass = 216g/27g/mol = 8molfrom equation: amount Al2O3/amount Al =2/4amount Al2O3 =amount of Al * 2/4= 8 mol *2/4 =4molmass Al2O3 = amount*molar mass =4mol*204gmol =408gFrom equation amount of O2/amount of Al =3/4amount of O2 =amount of Al*3/4 = 8mol *3/4mol = 6molmolar mass of O2 = 32g/molmass of O2 = amount of O2 * molar mass of O2mass of O2 = 6mol *32g/mol = 192gFor the reaction N2(g) +3H2(g) ---> 2NH3(g)</strong><br /><strong></strong><br /><strong></strong><br /><strong>Calculate the masses and volumes of nitrogen and hydrogen needed to make 17g of ammonia NH3.</strong><br /><strong></strong><br /><strong></strong><br /><strong> Converting mass-concentration into mol dm-3 and vice versaconcentration = mass/volume OR concentration = amount/volume</strong><br /><strong></strong><br /><strong>To convert them just change masses into amounts or vice versa.e.g. What is the concentration in mol/dm3 of a solution of sodium hydroxide NaOH of concentration 4g/dm3?</strong><br /><strong></strong><br /><strong>amount of NaOH in 1 dm3 = mass of NaOH/molar mass of NaOHamount of NaOH in 1 dm3 = 4g/40g/mol = 0.1mol so concentration of NaOH is 0.1mol/dm3 = 0.1MNB a concentration of 1M = 1mol/dm3.</strong><br /><strong></strong><br /><strong></strong><br /><strong></strong><br /><strong>Some dilute sulphuric acid, H2SO4, had a concentration of 4.90gdm-3. What is its concentration in mol dm-3?2. What is the concentration in gdm-3 of some potassium hydroxide, KOH, solution with a concentration of 0.200 mol dm-3?3. </strong><br /><strong>What mass of sodium carbonate, Na2CO3, would be dissolved in 100cm3 of solution in order to get a concentration of 0.100 mol dm-3?</strong><br /><strong></strong><br /><strong> Simple calculations from the results of titrationse.g.</strong><br /><strong></strong><br /><strong> What is the concentration of a solution of sodium hydroxide NaOH if 10cm3 of the NaOH require 20cm3 of a 0.5M solution of sulphuric acid H2SO4 for neutralisation in a titration.</strong><br /><strong></strong><br /><strong></strong><br /><strong>amount of H2SO4 = concentration of H2SO4 * volume of H2SO4amount of H2SO4 = 0.5mol/dm3 *20/1000dm3 = 0.01molH2SO4 + 2NaOH ---> Na2SO4(aq) + 2H2O(l)so amount of NaOH/amount of H2SO4=2/1so amount of NaOH = amount of H2SO4*2/1 = 0.01mol *2/1 = 0.02molconcentration of NaOH = amount of NaOH/volume of NaOH concentration of NaOH = 0.02mol/20/1000dm3 = 1mol/dm3NB 1cm3 = 1/1000dm3</strong><br /><strong></strong><br /><strong></strong><br /><strong></strong><br /><strong> What is the concentration of hydrochloric acid, 25.0cm3 of which neutralise 20.0cm3 of sodium hydroxide solution of concentration 0.15moldm-3. (ans = 0.15M)2. </strong><br /><strong></strong><br /><strong>What is the concentration of sulphuric acid, 20.0cm3 of which neutralise 30.0cm3 of a potassium hydroxide solution of concentration 0.1moldm-3 (ans=0.1M)3. </strong><br /><strong></strong><br /><strong>What is the concentration of sodium hydroxide, 10.0cm3 of which neutralise 15.0cm3 of hydrochloric acid solution of concentration 2.5moldm-3? (ans=2.5M)4. </strong><br /><strong></strong><br /><strong>What is the concentration of nitric acid, 10.0cm3 of which react with 25.0cm3 of a solution of sodium carbonate of concentration 0.2moldm-3? (ans = 0.2M)</strong><br /><strong></strong><br /><strong></strong><br /><strong></strong>Ida stanlyhttp://www.blogger.com/profile/17714974727845318262noreply@blogger.com0tag:blogger.com,1999:blog-4668405857291176469.post-85458289623731784902008-11-27T06:29:00.000-08:002009-11-27T00:07:26.324-08:00Hard water- GCSE CHEMISTRY<strong>Hard water<br />definition of hard water</strong><br /><strong>Soft water e.g. distilled water, easily forms a lather with soap.</strong><br /><strong>Hard water e.g. London tap water, does not easily form a lather and forms a scum.</strong><br /><a href="http://www.drbateman.net/gcse2003/gcsesums/chemsums/hardwater/teaching_activity_1.htm"></a><strong>Soaps and soapless detergentsDetergents are chemicals with large molecules which help clean. </strong><br /><strong>They have one end which dissolves in oil and one end which is ionic and dissolves in water.</strong><br /><strong>oil soluble end C17H35COO-Na+ water soluble ionic end Hard water contains soluble calcium and/or magnesium salts. It contains calcium ions Ca2+(aq), which can be detected by a</strong> <strong>flame test or by testing with sodium hydroxide and/or magnesium ions Mg2+(aq).A soap has ions which react with ions in hard water to form a precipitate (a scum). </strong><br /><strong>e.g. sodium stearate C17H35COO-Na+ is a soap. </strong><br /><strong>stearate ion + calcium ion ---> calcium stearate </strong><br /><strong>Calcium stearate is insoluble so forms a precipitate (a scum) in hard water. </strong><br /><strong><br /></strong><strong>2C17H35COO-(aq) + Ca2+(aq) ---> (C17H35COO)2Ca(s)</strong><br /><a name="sulfonate"><strong>A soapless detergent</strong></a><strong> has ions which do not react with the ions in hard water.e.g. sodium 3-dodecylbenzene sulfonate</strong><br /><strong>C18H29SO3-Na+ is a soapless detergent.</strong><br /><strong>C18H29SO3-Na+ and (C18H29SO3)2Ca are both soluble so no scum forms in hard water</strong><strong>.</strong><br /><strong>Draw labelled diagrams to show beakers with the ions and molecules that they contain for </strong><br /><strong>(a) soft water, hard water, </strong><br /><strong>soft water + soap, </strong><br /><strong>soft water + soapless detergent, hard water + soap, </strong><br /><strong>hard water + soapless detergent.</strong><br /><strong>Limestone, chalk and gypsum and hard water</strong><br /><strong>Hard water forms when calcium or magnesium salts in rock dissolve in rain water as it flows through the rock.</strong><br /><strong>Gypsum is a rock containing calcium sulfate.</strong><br /><strong>Calcium sulfate is insoluble but a little does dissolve to leave some calcium ions in the water where is has past over gypsum.Limestone and chalk are rocks containing calcium carbonate. </strong><br /><strong>Calcium carbonate is very insoluble and none of it dissolves as water passes over limestone or chalk. </strong><br /><strong>Calcium ions from limestone and chalk do dissolve to make water hard in a reaction with carbonic acid.</strong><br /><strong>water + carbon dioxide ---> carbonic acid</strong><br /><strong>H2O(l) + CO2(g) ---> H2CO3(aq)</strong><br /><strong>calcium carbonate + carbonic acid ---> calcium hydrogencarbonate</strong><br /><strong>CaCO3(s) + H2CO3(aq) ---> Ca(HCO3)2(aq)</strong><strong>does not exist!</strong><br /><br /><strong>Industrial and domestic problems caused by scaleHard water normally contains dissolved calcium hydrogencarbonate. This can slowly change back into insoluble calcium carbonate but the change is speeded up by heating. </strong><br /><strong>The solid calcium carbonate formed is called scale.</strong><br /><strong>calcium hydrogencarbonate ---> calcium carbonate + carbon dioxide +water</strong><br /><strong></strong><br /><strong>Ca(HCO3)2(aq)) ---> CaCO3(s) + H2O(l) + CO2(g) </strong><br /><strong>scale</strong><br /><strong>Scale forms on a kettle's heating element insulating it and wasting energy when it boils.Scale forms inside hot water pipes which can even block a pipe.</strong><br /><strong>Stalactites and stalagmites are made of calcium carbonate and form in caves in hard water areas. Explain how this might happen.</strong><br /><strong>Benefits of hardness in water</strong><br /><strong>The formation of thin layers of scale on the inside of pipes can be useful.Corrosion is reduced because the water in the pipes is not in contact with the metal.Poisonous metal salts of lead or copper from the metal surface of pipes cannot enter drinking water if the metal surface is covered in scale.Calcium is needed in the diet for healthy bones and teeth.</strong><br /><strong>The treatment of water to make it suitable for domestic use </strong><br /><strong></strong><br /><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjkfTYv7Eoe-CZmyt1P6acFWtZ9PGvqJoI3101-OSLtWzL7QTxiElB-OstQXsvEkpdYgGxAdZgv9BCO7dcuHLoLiiRL8_sTxr548PHmgQ-mfPciRH3noK6gkhN4Us9Ti_reicMpESv88RiA/s1600-h/hardwa1.gif"><strong><img id="BLOGGER_PHOTO_ID_5273344998853020786" style="FLOAT: right; MARGIN: 0px 0px 10px 10px; WIDTH: 400px; CURSOR: hand; HEIGHT: 84px" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjkfTYv7Eoe-CZmyt1P6acFWtZ9PGvqJoI3101-OSLtWzL7QTxiElB-OstQXsvEkpdYgGxAdZgv9BCO7dcuHLoLiiRL8_sTxr548PHmgQ-mfPciRH3noK6gkhN4Us9Ti_reicMpESv88RiA/s400/hardwa1.gif" border="0" /></strong></a><br /><strong><br /></strong><br /><br /><br /><br /><strong></strong>Ida stanlyhttp://www.blogger.com/profile/17714974727845318262noreply@blogger.com0tag:blogger.com,1999:blog-4668405857291176469.post-11062826130964347892008-11-27T06:25:00.000-08:002009-11-27T08:13:28.671-08:00Collection of gases-IGCSE /GCSE CHEMISTRY<div><div><div><strong>Collection and identification of gases</strong></div><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgGsrnt7mxpiFP_qOStl5vTNtczr42Uj6IMp9okpTobujgADuPqgD4NypAd1JlXE5LGWjPFvrnnFlkUBsxm3a4Todeq0m-Q-kiTtZPqfGdGPG-xWVhZy9FbfNuDlGkjCRpaFIeHkOliEsTn/s1600-h/gases.6"><img id="BLOGGER_PHOTO_ID_5273343839631081250" style="FLOAT: right; MARGIN: 0px 0px 10px 10px; WIDTH: 400px; CURSOR: hand; HEIGHT: 305px" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgGsrnt7mxpiFP_qOStl5vTNtczr42Uj6IMp9okpTobujgADuPqgD4NypAd1JlXE5LGWjPFvrnnFlkUBsxm3a4Todeq0m-Q-kiTtZPqfGdGPG-xWVhZy9FbfNuDlGkjCRpaFIeHkOliEsTn/s400/gases.6" border="0" /></a> <strong><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjmnqxZvNfChcUPnmNCNIzU7hHt9JtwG7mpUhWqzx1yOxN0ffj6cJpvb5ItrhuqduaJ9i8KZEOiCe-nkggkpCyPKkMhj4QDl67z9Q42rSA4hZbzB8Yl1o33oZuCvUtL1VTt3vjtQ3SpA4VB/s1600-h/gases.8"><img id="BLOGGER_PHOTO_ID_5273343971283856338" style="FLOAT: right; MARGIN: 0px 0px 10px 10px; WIDTH: 250px; CURSOR: hand; HEIGHT: 200px" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjmnqxZvNfChcUPnmNCNIzU7hHt9JtwG7mpUhWqzx1yOxN0ffj6cJpvb5ItrhuqduaJ9i8KZEOiCe-nkggkpCyPKkMhj4QDl67z9Q42rSA4hZbzB8Yl1o33oZuCvUtL1VTt3vjtQ3SpA4VB/s400/gases.8" border="0" /></a>Methods for collecting gasesdownward deliverysuitable for heavy dense gas solubility not important e.g. chlorine, upward deliverysuitable for light low density gas, solu<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjoPPExorrtXC82tV2TjI-09l8JW8RK9VbKp81cG9ARh77YIKDCVpVm-3d3IOR6dDJlxHZpT8a9o4GlHE7NJKZXuj69lBN_x8v6lBI-5XaweCrpt3v_D2aohJmDRlzGXgDQaVJG82gqwQpH/s1600-h/gases.7"><img id="BLOGGER_PHOTO_ID_5273343906780865026" style="FLOAT: right; MARGIN: 0px 0px 10px 10px; WIDTH: 305px; CURSOR: hand; HEIGHT: 102px" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjoPPExorrtXC82tV2TjI-09l8JW8RK9VbKp81cG9ARh77YIKDCVpVm-3d3IOR6dDJlxHZpT8a9o4GlHE7NJKZXuj69lBN_x8v6lBI-5XaweCrpt3v_D2aohJmDRlzGXgDQaVJG82gqwQpH/s400/gases.7" border="0" /></a>bility not important e.g hydrogen</strong><br /><br /><br /><br /><div><strong></strong></div><br /><br /><br /><br /><div><br /><strong>collection over waterSuitable for any gas with a low solubility e.g. nitrogencollection using a gas syringeSuitable for any gas especially if volume is to be measured.Learning activity - use the data in the table and the rules above to select a collection me<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEju1echrX3vpzNSFcgWbNHkivqjkxRJuk9mr7GkMi1GeV6DBVh6H3H6qIwtNws4jCWZR4pGaw1Oq1g0qXNyOohpTKQfu1y2a5fwqzkd9TiYaw5ckX_yqS7UuBe-4plIxQ-KmBhvNsbyBuz2/s1600-h/gases.5"><img id="BLOGGER_PHOTO_ID_5273343765927577202" style="FLOAT: right; MARGIN: 0px 0px 10px 10px; WIDTH: 359px; CURSOR: hand; HEIGHT: 240px" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEju1echrX3vpzNSFcgWbNHkivqjkxRJuk9mr7GkMi1GeV6DBVh6H3H6qIwtNws4jCWZR4pGaw1Oq1g0qXNyOohpTKQfu1y2a5fwqzkd9TiYaw5ckX_yqS7UuBe-4plIxQ-KmBhvNsbyBuz2/s400/gases.5" border="0" /></a>thod and give a reason.</strong></div><br /><br /><div><strong><br /></strong></div><div><strong>Hazards with common gasesHydrogen - flammable, explosive when mixed with air. Use in small amounts.Hydrogen chloride and sulphur dioxide- poisonous as they are very acidic. Use small amounts and only in the fume cupboard.</strong></div></div></div>Ida stanlyhttp://www.blogger.com/profile/17714974727845318262noreply@blogger.com0tag:blogger.com,1999:blog-4668405857291176469.post-21723799805649341712008-11-27T06:16:00.000-08:002008-12-14T22:07:14.020-08:00Titration-IGCSE /GCSE-CHEMISTRY<strong>Titration<br />Reasons for using titrationWhen an acid and an alkali react it is not possible to see the end of the reaction unless an indicator is used. If an indicator is used the salt made will be impure. Titration is used to find out exactly what volume of acid and alkali should be mixed.</strong><br /><br /><strong></strong><br /><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjuJuaCs5-GRpA9cBqmCIWyQxvR8NdJ6n54CMdodMa29ZgmYwe-iPvOuDYTvP4eAx6pkRgD-L-trInSpQjs1FwT5AcxHUg3tpRXivKrfNdwccdM35MOiKurRi0o6R05VxenyoxehP8OAws9/s1600-h/titrat4.gif"><strong><img id="BLOGGER_PHOTO_ID_5273341492137731698" style="FLOAT: right; MARGIN: 0px 0px 10px 10px; WIDTH: 49px; CURSOR: hand; HEIGHT: 400px" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjuJuaCs5-GRpA9cBqmCIWyQxvR8NdJ6n54CMdodMa29ZgmYwe-iPvOuDYTvP4eAx6pkRgD-L-trInSpQjs1FwT5AcxHUg3tpRXivKrfNdwccdM35MOiKurRi0o6R05VxenyoxehP8OAws9/s400/titrat4.gif" border="0" /></strong></a><strong><br /><img id="BLOGGER_PHOTO_ID_5273341328012465378" style="DISPLAY: block; MARGIN: 0px auto 10px; WIDTH: 285px; CURSOR: hand; HEIGHT: 372px; TEXT-ALIGN: center" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh7tKYvdmYsy8AZZXd48lstORTWihpyfpkLfGwGH93PtaeFLIfaryXsjRCq3IW9YvY0yD7WEjqpmOnHocW01J-LVVWWEMqfTfTBCvw9hyphenhyphenPO4teXl1QdoGpkVJcpu6aKW_H6YV9ZBuHyrDqz/s400/titrat2.gif" border="0" /><br /><br /></strong><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg1rAAVN-q1drTiyPfmbVWp2oPg3PXAQO4VebdczvG13sEowY2SqHR8OgP28qUJFdeVF9t0G3aXMAe_Hu9kYWdNQpIWG_T-3Ps5zTfhpC9ieFGTD6CXi2EHRFe8GtjH-jX1x7LSFKeyCMg4/s1600-h/titrat1.jpg"><strong><img id="BLOGGER_PHOTO_ID_5273341242406158578" style="FLOAT: right; MARGIN: 0px 0px 10px 10px; WIDTH: 71px; CURSOR: hand; HEIGHT: 400px" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg1rAAVN-q1drTiyPfmbVWp2oPg3PXAQO4VebdczvG13sEowY2SqHR8OgP28qUJFdeVF9t0G3aXMAe_Hu9kYWdNQpIWG_T-3Ps5zTfhpC9ieFGTD6CXi2EHRFe8GtjH-jX1x7LSFKeyCMg4/s400/titrat1.jpg" border="0" /></strong></a><strong><br /></strong><br /><strong>Methods for carrying out titration</strong><br /><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg1rAAVN-q1drTiyPfmbVWp2oPg3PXAQO4VebdczvG13sEowY2SqHR8OgP28qUJFdeVF9t0G3aXMAe_Hu9kYWdNQpIWG_T-3Ps5zTfhpC9ieFGTD6CXi2EHRFe8GtjH-jX1x7LSFKeyCMg4/s1600-h/titrat1.jpg"><strong></strong></a><br /><strong>1.Fill a 25cm3 pipette up to the line with the alkali solution of known concentration. </strong><br /><strong>2. Transfer exactly 25.0cm3 of alkali to a conical flask and add an indicator.</strong><br /><strong>3. Rinse a burette with acid then fill it with the acid using a funnel.Burette</strong><br /><strong>4. Carefully run acid from the burette int the conical flask until the indicator changes colour.</strong><br /><br /><br /><img id="BLOGGER_PHOTO_ID_5273341412168451298" style="DISPLAY: block; MARGIN: 0px auto 10px; WIDTH: 212px; CURSOR: hand; HEIGHT: 400px; TEXT-ALIGN: center" alt="" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhRrk4jpV8geyFSUOGFa2o0kRCqDXJZVFOigLNiwMY95Eu5hx0qIlUnFdJ41bD2yM7YPnuIzz2i17r5iR2LUP9uja0dQQopMrgSAbwC0QDzan9tRbmB7ulVQfLffBAHYfJ06wpvOZfMLjU3/s400/titrat3.gif" border="0" />Ida stanlyhttp://www.blogger.com/profile/17714974727845318262noreply@blogger.com0tag:blogger.com,1999:blog-4668405857291176469.post-39546582776453886792008-11-27T06:13:00.000-08:002008-12-14T22:07:39.733-08:00method for salt preparation-IGCSE CHEMISTRY<strong>Choosing a method for salt </strong><br /><strong></strong><br /><strong>preparationSalts can be made by the following methods:</strong><br /><strong></strong><br /><strong>direct combination not normally used in school labs</strong><br /><strong></strong><br /><strong>e.g. iron + sulphur ----> iron sulphide</strong><br /><strong></strong><br /><strong>adding a carbonate to an </strong><br /><strong></strong><br /><strong>acidcarbonate + acid ---> salt + water + carbon dioxide</strong><br /><strong></strong><br /><strong>calcium carbonate + hydrochloric acid ---> callcium chloride + water + carbon dioxide</strong><br /><strong></strong><br /><strong>normally used to make soluble salts from insoluble carbonate, the reaction is complete (the acid is neutralised) when the effervescence (fizzing) finishes and some undissolved solid remains, filter, crystallise, filter again, wash and dry to obtain saltadding a metal to an </strong><br /><strong></strong><br /><strong>acidmetal + acid ---> salt + hydrogeniron + sulfuric acid ---> iron II sulfate + hydrogen</strong><br /><strong></strong><br /><strong>normally used to make soluble salts, the reaction is complete (the acid is neutralised) when the effervescence (fizzing) finishes and some undissolved solid remains, filter and crystallise, filter again, wash and dry to obtain saltadding an base to an acidacid + base ---> salt + water</strong><br /><strong></strong><br /><strong>normally used to make soluble salts from an insoluble base (most oxides and hydroxides),nitric acid + copper oxide ---> copper nitrate + waterthe reaction is complete (the acid is neutralised) when some undissolved solid remains, filter and crystallise, filter again, wash and dry to obtain saltIf a solution of a soluble base (an alkali e.g. soluble hydroxide) is used titration is carried out first to find out how alkali to add, crystallise, filter, wash and dry to obtain saltlearning activity -</strong><br /><strong> Forming precipitatesprecipitationsoluble salt1 + soluble salt2 ----> insoluble salt + soluble salt3</strong><br /><strong>sodium chloride + lead nitrate ----> lead chloride + sodium nitrateused to make insoluble salts from two solutions of soluble saltslearning activity - choose suitable pairs of solutions to make the following insoluble salts:calcium carbonate, barium sulfate, silver chloride, zinc carbonate, and lead chloride.</strong><br /><strong></strong><br /><strong>Purification of insoluble saltsWhen made an insoluble salt made is filtered, washed with distilled water and dried.</strong>Ida stanlyhttp://www.blogger.com/profile/17714974727845318262noreply@blogger.com0