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24 October 2014. 7.3 Making salts from solutions. Soluble or insoluble? What do these terms mean?. Water Treatment. Fertilisers. 24 October 2014. 7.3 Making salts from solutions. Indicators are needed to check producing a soluble salt from an alkali and acid.
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24 October 2014 7.3 Making salts from solutions Soluble or insoluble? What do these terms mean? Water Treatment Fertilisers
24 October 2014 7.3 Making salts from solutions • Indicators are needed to check producing a soluble salt from an alkali and acid. • Insoluble salts produce a precipitate when reacting two solutions. • Precipitation is an important way of removing some substances from waste water. Soluble = Able to dissolve in a solvent. Insoluble = Unable to dissolve in a solvent. Precipitate = A solid material produced from a solution.
Acid + alkali 1 2 3 4 5 6 7 8 9 10 11 12 13 14 sodium hydroxide pH 14 hydrochloric acid pH 1 sodium chloride pH 7 Increasingly acid Increasingly alkali A neutralisation reaction is where an acid reacts with a alkali to produce a neutral solution of a saltandwater. alkali neutralisation Salt How can the salt be separated from the water?
Neutralisation reactions: hydroxides Each OH- ion reacts with one H+ ion. Reaction with hydroxides: H+ + OH- H2O Eg. Potassium +hydrochloric water + potassium hydroxide acid chloride KOH+ HCl H2O+ KCl Eg. Calcium + sulphuric water + calcium hydroxide acid sulphate Ca(OH)2+ H2SO4 2H2O+ CaSO4 Water can be evaporated to leave the salt behind.
Insoluble Salts • A precipitation reaction leaves behind a solid material. E.g. Lead Nitrate + Sodium Chloride → Lead Chloride + Sodium Nitrate Pb(NO3)2(aq) + 2NaCl (aq) → PbCl2(s) + 2NaNO3(aq) • Practical • Add sodium chloride to lead nitrate and stir. • Filter the precipitate. • Wash and dry precipitate. Place on a watch glass. • Write down what the Lead Chloride looks like.
24 October 2014 7.3 Making salts from solutions • Indicators are needed to check producing a soluble salt from an alkali and acid. • Insoluble salts produce a precipitate when reacting two solutions. • Precipitation is an important way of removing some substances from waste water. Soluble = Able to dissolve in a solvent. Insoluble = Unable to dissolve in a solvent. Precipitate = A solid material produced from a solution.