The equation shown in (a)(i) describes the reaction which occurs when aqueous potassium iodide is added to aqueous copper(II) sulfate. A white precipitate of copper(I) iodide forms in a brown solution of iodine and potassium sulfate.

1. (a)(i)Balance the equation and include state symbols. ......CuSO₄(.....) + ......KI(.....) → ......CuI(.....) + ......I₂(.....) + ......K₂SO₄(.....) The table gives the oxidation numbers of iodine in the different species in the equation. iodine-containing species oxidation number of iodine KI -1 CuI -1 I₂ 0[2]
2. (a)(ii)Deduce the oxidation number of copper in CuSO₄ and CuI. • oxidation number of copper in CuSO₄ • oxidation number of copper in CuI[1]
3. (a)(iii)Describe the type of reaction shown by the equation in (a)(i). Explain your answer in terms of electron transfer.[2]
4. (b)In the reaction described in (a)(i), a student uses 17.43g of CuSO₄•yH₂O. By further titration of the reaction products the student concludes that the total amount of CuSO₄ in the sample is 0.0982 mol. Use the Data Booklet to complete the table to calculate the value of y, where y is an integer. Show your working. mass of 0.0982 mol CuSO₄ g amount of H₂O in 17.43 g of CuSO₄•yH₂O mol H₂O value of y y =[4]