1. Standard Grade Revision Unit 10 Q1. Pairs of metals are used to produce a cell. Standard Grade Chemistry (a)What is the purpose of the filter paper soaked in sodium chloride solution? (b)What is the direction of the electron flow through the wires? (c) Give the name of a metal which could replace the nickel and cause the electrons to flow in the opposite direction. (d) Cells are used in calculators and watches. Give one advantage of a cell compared with mains electricity. (a) Acts as the electrolyte – a conducting solution used to complete the circuit by allowing a flow of ions. (b) Electrons flow from nickel to copper. (c) Gold or silver. (d) Cells allow equipment to be portable and cells not as dangerous as mains.

2. Unit 10 Revision Q2. The diagram shows a copper/zinc cell. Standard Grade Chemistry (a) In the cell, electricity flows through the wires from the zinc to the copper. Name the type of charged particle that flows through the wires. (b) What is the purpose of the ion-bridge? (c) Eventually the cell would stop producing electricity. Give a reason for this. (d) Name a metal which could replace zinc to produce a larger voltage. You may wish to use page 7 of the data booklet. (a) Electrons flow through the wires. (b) Completes the circuit by allowing a flow of ions. (c) One of the chemicals in the cell gets used up. (d) Magnesium.

3. Unit 10 Revision Standard Grade Chemistry Q3. In an alkaline manganese battery the positive electrode is made of a mixture of manganese dioxide and carbon. The negative electrode is powdered zinc. The electrodes are in a paste made of potassium hydroxide. (a) (i) Suggest why this type of battery is known as an alkaline battery. (ii) Why is the potassium hydroxide used in the form of a paste and not as a dry powder? (b) Car batteries can be recharged. (i) What type of electrolyte is used in a car battery? (ii) Give one example of a battery that can be recharged. (a) (i) The potassium hydroxide is an alkali. (ii) The ions are not free move in a dry powder. (b) (i) Sulphuric acid. (ii) Nickel/Cadmium battery. Q4. A simple cell can be made from everyday objects. (a) In which direction do electrons flow through the wires? (b) What would happen to the voltage if the iron nail was replaced with aluminium foil? You may wish to use page 7 of the data booklet. (a) From iron to copper. (b) Increase.

4. Unit 10 Revision. Standard Grade Chemistry Q4. Helen set up the cell shown opposite The reaction taking place at electrode A is Fe 3+ (aq) + e-  Fe 2+ (aq) (a) (i) In which direction do electrons flow. (ii) What term is used to describe the type of chemical reaction taking place at electrode A? (b) Iodine forms at electrode B. (i) What would you see happening around electrode B? (ii) Write an ion-electron equation for the chemical reaction taking place at electrode B. You may wish to use the data booklet to help you. (a) (i) From the iodide solution to the iron(III) solution (from B to A). (ii) Reduction (gain of electrons) (b) (i) A blue black colour appears. (ii) 2I - (aq)  I 2 (aq) + 2e -

5. Unit 10 Revision. Standard Grade Chemistry Q5. Roy wanted to show that chemicals can be used to produce an electric current. When the crocodile clips (labelled A and B) were attached to certain parts of the apparatus, the ammeter gave a reading. (a) (i) Where should the crocodile clips be attached to complete the circuit? (ii) Why was no current produced when the porous cardboard container was replaced by a glass beaker? (iii) What would happen to the reading on the ammeter if the zinc rod was replaced with a tin rod in a tin chloride solution? (b) Roy was instructed to make 50 cm 3 of a 1 mol/litre solution of copper chloride, CuCl 2. Calculate the mass, in grams, of copper chloride needed. (a) (i) To the copper can and zinc rod. (as shown) (ii) Ions cannot flow through the glass but they can flow through cardboard. (iii) Reading would fall. (b) 6.825 g

6. Standard Grade Chemistry Unit 10 Revision. Q6. Copper displaces silver from silver(I) nitrate solution. Cu(s) + 2Ag + (aq) + 2 NO 3 - (aq)  Cu 2+ (aq) + 2 NO 3 - (aq) + 2Ag(s) (a) Rewrite this equation omitting the spectator ions. (b) Write the ion-electron equation for the oxidation step in the displacement reaction. (c) Write the ion-electron equation for the reduction step in the displacement reaction. (a)Cu(s) + 2Ag + (aq)  Cu 2+ (aq) + 2Ag(s) (b)Cu(s)  Cu 2+ (aq) + 2e - (c) Ag + (aq) + e -  Ag(s) Q7. Pairs of metals can be used to produce a voltage zinc copper Filter paper soaked in sodium chloride solution. magnesiumlead tin iron Identify the metal in the box above which would produce the smallest voltage is used in place of zinc. lead

7. Standard Grade Chemistry Q8. Sarah set up the circuit shown below. Solution containing sulphite, SO 3 2- ions Solution containing bromine, Br 2 (aq) In beaker B sulphite ions are converted to sulphate ions. SO 3 2- (aq) + H 2 O(l)  SO 4 2- (aq) + 2H + (aq) + 2 e – (a) In which direction do the electrons flow through the ammeter? (b) (i) What term is used to describe the type of chemical reaction taking place in beaker B? ( ii) Suggest what would happen to the pH in beaker B. (c) Write the ion-electron equation for the chemical reaction taking place in beaker A. You may wish to use the data booklet to help you. (a) From the sulphite in beaker B to the bromine solution in beaker A. (b) (i) Oxidation (loss of electrons). (ii) pH will fall as hydrogen ions are being produced making the solution acidic. (c) Br 2 (a) + 2e -  2Br - (aq) Unit 10 Revision.

8. Standard Grade Chemistry Q9. The diagram shows a cell which can produce electricity. (a) What is the purpose of the ion-bridge? (b) Name a tin compound which could be used to make the solution containing tin ions. (c) In which direction do electrons flow in this cell? (d) Which electrode will decrease in mass when the cell is operating? (e) The magnesium electrode undergoes oxidation in this cell. Write an ion-electron equation for the oxidation reaction. (f) Name a metal and a solution which could replace the tin and the solution containing tin ions which would give a higher voltage than the cell shown. voltmeter tin solution containing tin ions solution containing magnesium ions magnesium V (a) Completes the circuit. (b) Tin chloride or other soluble tin compound. (c) From magnesium to tin (d) Magnesium (e) Mg  Mg 2+ + 2e - (f) Lead or copper, silver or gold