4. Electrochemistry
A section of Chemistry, 0620
Listing 10 of 500 questions
Use The electroplating of iron with chromium involves four stages. 1. The iron object is cleaned with sulphuric acid, then washed with water. 2. The iron is plated with copper. 3. It is then plated with nickel to prevent corrosion. 4. It is then plated with chromium. The equation for stage 1 is Fe + H2SO4 FeSO4 + H2 Write a word equation for this reaction. Describe a test for the gas given off in this reaction. test result The diagram shows how iron is electroplated with copper. + _ rod of pure copper iron object copper(sulphate solution Choose a word from the list below which describes the iron object. Put a ring around the correct answer. anion anode cathode cation What is the purpose of the copper(sulphate solution? Every reasonable effort has been made to trace all copyright holders where the publishers (i.e. UCLES) are aware that third-party material has been reproduced. The publishers would be pleased to hear from anyone whose rights they have unwittingly infringed. University of Cambridge International Examinations is part of the University of Cambridge Local Examinations Syndicate (UCLES), which is itself a department of the University of Cambridge. Examiner's Use Describe what happens during the electroplating to the iron object, the rod of pure copper. Describe a test for copper(ions. test result Suggest why chromium is used to electroplate articles. The information below shows the reactivity of chromium, copper and iron with warm hydrochloric acid. chromium – few bubbles of gas produced every second copper – no bubbles of gas produced iron – many bubbles of gas produced every second Put these three metals in order of their reactivity with hydrochloric acid. Most reactive → Least reactive →
0620_s05_qp_2
THEORY
2005
Paper 2, Variant 0
View
For Examiner's Use A student placed a crystal of copper(sulphate in a beaker of water. After one hour the crystal had completely disappeared and a dense blue colour was observed in the water at the bottom of the beaker. After 48 hours the blue colour had spread throughout the water. water copper(sulphate crystal after 1 hour after 48 hours Use the kinetic particle theory to explain these observations. Describe the arrangement and motion of the particles in the copper(sulphate crystal. arrangement motion Copper ions can be separated from other metal ions by paper chromatography. Draw a labelled diagram of the apparatus for paper chromatography. In your diagram include • the solvent, • the spot where the solution containing copper ions is placed. For Examiner's Use Copper can be purified by electrolysis. impure copper foil pure copper foil copper(sulphate solution + – Choose a word from the list below which describes the pure copper foil. Put a ring around the correct answer. anion anode cathode cation electrolyte Describe what happens during this electrolysis to the pure copper foil, the impure copper foil.
0620_s08_qp_2
THEORY
2008
Paper 2, Variant 0
View
For Examiner's Use Hydrogen chloride can be made by burning hydrogen in chlorine. Complete the equation for this reaction. H2 + ………… ……… HCl Draw a dot and cross diagram for a molecule of hydrogen chloride. Show all the electrons. use o for an electron from a hydrogen atom use x for an electron from a chlorine atom Hydrochloric acid is formed when hydrogen chloride gas dissolves in water. Suggest the pH of hydrochloric acid. Put a ring around the correct answer. pH 1 pH7 pH9 pH 13 Complete the equation for the reaction of hydrochloric acid with zinc. zinc + hydrochloric acid zinc chloride + ……………… Describe how dry crystals of zinc chloride can be obtained from a solution of zinc chloride. A student electrolysed molten zinc chloride. State the name of the product formed at the anode, the cathode.
0620_s09_qp_2
THEORY
2009
Paper 2, Variant 0
View
Lead is a grey metal. State two physical properties which are characteristic of metals. To which Group in the Periodic Table does lead belong? An isotope of lead has the mass number 208. Complete the table to show the number of subatomic particles in an atom of this isotope of lead. Use the Periodic Table to help you. type of particle number of particles electrons protons neutrons When lead is heated in oxygen, lead(oxide is formed. Write a word equation for this reation. When lead(oxide is heated with carbon, lead and carbon monoxide are formed. PbO + C → Pb + CO Which substance becomes oxidised during this reaction? Carbon monoxide is a covalent compound. Which one of these statements about carbon monoxide is correct? Tick one box. It is a solid with a high melting point. It conducts electricity when it is a liquid. It is a gas at room temperature. It forms about 1 % of the atmosphere.
0620_s10_qp_22
THEORY
2010
Paper 2, Variant 2
View
Questions Discovered
500