Acids, Salts and the pH Scale

Question 1

Acids

Answer 1

Produce hydrogen ions (H+) in aqueous solutions, react with some metals to produce salts + hydrogen, neutralised by alkalis e.g soluble metal hydroxides + bases e.g insoluble metal hydroxides + metal oxides to produce salts + water, + by metal carbonates to produce salts, water + carbon dioxide

Question 2

pH Scale

Answer 2

Measures of acidity or alkalinity of solution, from 0 to 14, can be measured using universal indicator or pH probe, as pH decreases by one unit, hydrogen ion concentration of solution increases by factor of 10

Question 3

Strong acid

Answer 3

Completely ionised in aqueous solution e.g hydrochloric, nitric + sulfuric acids

Question 4

Weak acid

Answer 4

Only partially ionised in aqueous solutions e.g ethanoic, citric + carbonic acids

Question 5

Aqueous solutions

Answer 5

Aqueous solutions of alkalis contain hydroxide ions (OH–), aqueous solutions of acids have pH values of less than 7 + aqueous solutions of alkalis have pH values greater than 7, for given concentration of aqueous solutions, stronger acid, lower pH

Question 6

Neutral solution

Answer 6

Solution with pH 7

Question 7

Neutralisation reactions

Answer 7

In neutralisation reactions, between acid + alkali, hydrogen ions react with hydroxide ions to produce water: H+ (aq) + OH- (aq) into H20 (l)

Question 8

Dilute solution

Answer 8

Solution that contains small amount of solute dissolved in the solution

Question 9

Concentrated solution

Answer 9

Solution that contains large amount of solute dissolved in solution

Question 10

Solute

Answer 10

Substance that is dissolved in solvent, forming solution e.g salt

Question 11

Solvent

Answer 11

Substance that dissolves solute, forming solution, normally liquid e.g water, but it can be solid or gas

Question 12

Particular salt produced in neutralisation reaction

Answer 12

Depends on: acid used (hydrochloric acid produces chlorides, nitric acid produces nitrates,
sulfuric acid produces sulfates) + positive ions in base, alkali or carbonate

Question 13

Soluble salts

Answer 13

Can be made from acids by reacting them with solid insoluble substances e.g metals, metal oxides, hydroxides or carbonates, solid is added to acid until no more reacts + excess solid is filtered off to produce solution of the salt, salt solutions can be crystallised to produce solid salts

Question 14

Soluble

Answer 14

Substance is able to form solution, so it’s able to dissolve in solvent

Question 15

Insoluble

Answer 15

Substance is unable to form solution, so it’s unable to dissolve in solvent