Choosing a method for salt
preparationSalts can be made by the following methods:
direct combination not normally used in school labs
e.g. iron + sulphur ----> iron sulphide
adding a carbonate to an
acidcarbonate + acid ---> salt + water + carbon dioxide
calcium carbonate + hydrochloric acid ---> callcium chloride + water + carbon dioxide
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
acidmetal + acid ---> salt + hydrogeniron + sulfuric acid ---> iron II sulfate + hydrogen
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
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 -
Forming precipitatesprecipitationsoluble salt1 + soluble salt2 ----> insoluble salt + soluble salt3
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.
Purification of insoluble saltsWhen made an insoluble salt made is filtered, washed with distilled water and dried.
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