Chemistry · May / June 2021 · Paper 62 · Question 4
0620
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The question as text
The mineral epsomite contains hydrated magnesium sulfate. When epsomite is heated strongly, it loses water and eventually becomes anhydrous magnesium sulfate. Plan an investigation to find the percentage by mass of water in a sample of epsomite. Your plan should include how you would calculate the percentage by mass of water in epsomite. You have access to common laboratory apparatus. [6]
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any 6 from:
weighed sample / stated mass (e.g. 5 g) / known mass of epsomite
in a crucible
heated (strongly using a Bunsen burner / spirit burner)
reweigh
heat again, reweigh, continue until mass stops changing
calculate mass of water lost by original mass – final mass
calculate percentage water by 100 × mass water / original mass
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