## A Level Chemistry 9701/23/M/J/20 Q2

2 (a) Explain what is meant by the term relative isotopic mass.

(b) A sample of copper contains two isotopes, 63Cu and 65Cu. The relative atomic mass of the copper in this sample is 63.55. Calculate the percentage abundance of each of these isotopes. Show your working.

(c) (i) Name the type of bonding within a sample of solid copper

(ii) Draw a labelled diagram to show the bonding within a sample of solid copper.

(iii) State the electronic configuration of a copper atom.

(d) A student is provided with a sample of hydrated copper(II) sulfate, CuSO4•xH2O, and is asked to determine the value of x. The student dissolves a sample of the hydrated copper(II) sulfate in water and adds it to an

excess of aqueous potassium iodide to make a total volume of 250.0cm3 of solution. 2CuSO4 + 4KI → 2CuI + I2 + K2SO4 The amount of iodine produced during this reaction is found by titrating a sample of this solutioN with sodium thiosulfate solution.

25.0cm3 of the iodine-containing solution requires 20.0cm3 of 0.10moldm–3 sodium thiosulfate solution.

I2 + 2S2O3 2– → S4O6 2– + 2I–

(i) Calculate the amount, in mol, of copper(II) sulfate present in the original sample of hydrated copper(II) sulfate. Show your working.

(ii) A total of 7.98g of CuSO4 is present in 10.68g of CuSO4•xH2O. Complete each row of the table to calculate the value of x, where x is an integer.[Mr: CuSO4,159.6]

## Answer ( 1 )