When pink hydrated cobalt(II) chloride is heated, it undergoes thermal decomposition to form blue anhydrous cobalt(II) chloride and water vapour:
CoCl2⋅6H2O(s)→CoCl2(s)+6H2O(g) \text{CoCl}_2\cdot6\text{H}_2\text{O}(\text{s}) \rightarrow \text{CoCl}_2(\text{s}) + 6\text{H}_2\text{O}(\text{g}) CoCl2⋅6H2O(s)→CoCl2(s)+6H2O(g)In an experiment, a student heats 6.500 g6.500\text{ g}6.500 g of hydrated cobalt(II) chloride. After the reaction is complete, the mass of the remaining anhydrous solid is 3.550 g3.550\text{ g}3.550 g.
Calculate the mass of water vapour that has been released into the atmosphere. Give your answer to three significant figures.
258 exam-style questions on Edexcel GCSE Chemistry Calculations involving masses. Each one has a worked solution and a mark scheme showing where the marks go.