CIE Jun 2014 v3 Paper 2 Q2

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A sample of a hydrated double salt, Cu(NH4)x(SO4)2.6H2O, was boiled with an excess of sodium hydroxide. Ammonia was given off. PMT The ammonia produced was absorbed in 40.0 cm3 of 0.400 mol dm3 hydrochloric acid. The resulting solution required 25 cm3 of 0.12 mol dm3 sodium hydroxide to neutralise the excess acid. (a) Write the ionic equation for the reaction between ammonium ions and hydroxide ions.[1] (b) (i) Calculate the amount, in moles, of hydrochloric acid in 40.0 cm3 of 0.400 mol dm3 solution. (ii) Calculate the amount, in moles, of sodium hydroxide needed to neutralise the excess acid. This will be equal to the amount of hydrochloric acid left in excess. [1] (iii) Calculate the amount, in moles, of hydrochloric acid that reacted with ammonia. (iv) Calculate the amount, in moles, of ammonium ions in the sample of the double salt. [1] [1] [1] (v) The sample contained 0.413 g of copper. Use this information and your answer to (iv) to calculate the value of x in Cu(NH4)x(SO4)2.6H2O. (vi) Calculate the Mr of Cu(NH4)x(SO4)2.6H2O. [2] [1] [Total: 8]UCLES 2014 9701/23/M/J/14<br /> BLANK PAGE PMTUCLES 2014 9701/23/M/J/14 [Turn over<br />

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