CC9b Looking C3.5 Recall that as hydrogen 1) Demonstrate Students find out if the pH Teacher at acids ion concentration in a diluting copper sulfate value is linked to the demonstrates the solution increases by a solution, roughly concentration of the difference in pH factor of 10, the pH of the diluting it by 50% solution. between four solution decreases by 1 over and over again Starting with 0.1 mol dm-3 different solutions of C3.7 Explain the terms dilute until the colour cannot hydrochloric acid students acids with the same and concentrated, with seen. use accurate measuring concentration eg. respect to amount of Discuss the difference apparatus to dilute the hydrochloric acid substances in solution between dilute and solution successively by a (pH=1) sulfuric acid C3.8 Explain the terms weak concentrated solutions factor of 10 (pH=2) , ethanoic and strong acids, with in terms of the amount acid (pH=4) and respect to the degree of of solute in a unit The students then use pH carbonic acid dissociation into ions volume. Discuss ways meters to measure the pH of (pH=5). Then of measuring the solution (least to through class concentrations of highest concentration) discussion students solutions eg grams per are introduced to the litre or g dm-3 This should show the link difference between between pH and strong and weak Equipment: TBC concentration. Include acids and why they questions on concentration will have different and pH. pHs. Then show 2) Show students two students a fifth everyday solutions Equipment: TBC solution and measure that contain acids. eg. its pH (should be battery acid and fruit about 5). Ask juices. students if this is a Discuss why you can strong or weak acid? dink one but not the Tell them it is in fact even though they are a strong acid, discuss about the same to work out it must concentration? Test be a dilute solution the pH of each and of a strong acid.
CC9b Looking at acids C3.5 C3.7 C3.8 Recall that as hydrogen ion concentration in a solution increases by a factor of 10, the pH of the solution decreases by 1 Explain the terms dilute and concentrated, with respect to amount of substances in solution Explain the terms weak and strong acids, with respect to the degree of dissociation into ions 1) Demonstrate diluting copper sulfate solution, roughly diluting it by 50% over and over again until the colour cannot seen. Discuss the difference between dilute and concentrated solutions in terms of the amount of solute in a unit volume. Discuss ways of measuring concentrations of solutions eg grams per litre or g dm-3 Equipment: TBC 2) Show students two everyday solutions that contain acids. eg. battery acid and fruit juices. Discuss why you can dink one but not the even though they are about the same concentration? Test the pH of each and Students find out if the pH value is linked to the concentration of the solution. Starting with 0.1 mol dm-3 hydrochloric acid students use accurate measuring apparatus to dilute the solution successively by a factor of 10 The students then use pH meters to measure the pH of the solution (least to highest concentration) This should show the link between pH and concentration. Include questions on concentration and pH. Equipment: TBC Teacher demonstrates the difference in pH between four different solutions of acids with the same concentration eg. hydrochloric acid (pH=1) sulfuric acid (pH=2) , ethanoic acid (pH=4) and carbonic acid (pH=5). Then through class discussion students are introduced to the difference between strong and weak acids and why they will have different pHs. Then show students a fifth solution and measure its pH (should be about 5). Ask students if this is a strong or weak acid? Tell them it is in fact a strong acid, discuss to work out it must be a dilute solution of a strong acid.
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