4.1. Electrolysis
A subsection of Chemistry, 0620, through 4. Electrochemistry
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This question is about copper and its compounds. Copper has two different naturally occurring atoms, 63Cu and 65Cu. State the term used for atoms of the same element with different nucleon numbers. The atomic number of copper is 29. Complete the table to show the number of protons, neutrons and electrons in the particles of copper shown. 63Cu 65Cu2+ protons neutrons electrons  Relative atomic mass is the average mass of naturally occurring atoms of an element. The percentage of the naturally occurring atoms in a sample of copper is shown. 63Cu 65Cu 70% 30% Deduce the relative atomic mass of copper in this sample. Give your answer to one decimal place.  relative atomic mass = Anhydrous copper(sulfate is used to test for the presence of water. When this test is positive, hydrated copper(sulfate is formed. State the colour change seen during this test. from to Complete the chemical equation to show the reaction that takes place. CuSO4 + CuSO4•5H2O State how hydrated copper(sulfate can be turned back into anhydrous copper(sulfate. Describe a test for pure water. Aqueous copper(sulfate contains Cu2+ions. Describe what is seen when aqueous copper(sulfate is added to aqueous sodiumhydroxide, NaOH. Write the ionic equation for the reaction between aqueous copper(sulfate and aqueous sodiumhydroxide. Include state symbols. When solid copper(nitrate is heated copper(oxide, nitrogen dioxide and oxygen are formed. 2Cu(NO3)2 → 2CuO + 4NO2 + O2 Calculate the volume of nitrogendioxide formed at room temperature and pressure when 4.7 g of Cu(NO3)2 is heated. Use the following steps: ● calculate the mass of one mole of Cu(NO3)2  g ● calculate the number of moles of Cu(NO3)2 used  moles ● determine the number of moles of nitrogendioxide formed  moles ● calculate the volume of nitrogendioxide formed at room temperature and pressure.  dm3  Write the chemical equation to show the action of heat on sodium nitrate, NaNO3. 
0620_w21_qp_41
THEORY
2021
Paper 4, Variant 1
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