Copper(ii) sulfate crystals exist as the pentahydrate, CuSO₄.5H₂O. It is a salt hydrate. If it is heated quite strongly, the water of crystallisation is driven off and the anhydrous salt remains.

a. Explain the meaning of the terms shown in italics.

b. Describe the experiment you would carry out to collect a sample of the water given off when the salt hydrate was heated strongly. Your description should include a diagram of the apparatus used and a chemical equation to represent the process taking place.

c. Describe a chemical test you could carry out to show that the colourless liquid given off was water.

d. Describe one other test you could carry out to show that the colourless liquid obtained in this experiment was pure water.

e. Sometimes it is necessary to work out the percentage by mass of water of crystallisation as well as the number of moles of water present in a hydrated crystal.

(i) Use the information given to calculate the percentage, by mass, of water of crystallisation in a sample of hydrated magnesium sulfate.

Mass of crucible = 14.20 g

Mass of crucible +

hydrated MgSO4 = 16.66 g

Mass after heating = 15.40 g

(ii) Calculate the number of moles of water of crystallisation driven off during the experiment as well as the number of moles of anhydrous salt remaining.

(Ar: H = 1; O = 16; Mg = 24; S = 32)

(iii) Using the information you have obtained in (ii), Write down, in the form MgSO₄.xH₂O, the formula of hydrated magnesium sulfate.