A hydrous salt is composed of anions and cations which are surrounded by a weakly
bonded water molecule. Each hydrous salt has a fixed number of water molecules
associated with it. When a salt holds a water molecule, we call it a hydrated or
hydrous salt.
9.1 Write down the term that best describes the water molecule that is weakly
bonded with salt. (1)
9.2 An unknown salt is found to contain 30,6% of water. The formula mass for
anhydrous salt (AS) is 100 amu.
9.2.1 Calculate the amount of water bonded with an unknown salt. (3)
9.2.2 An anhydrous salt above consists of a metal with a molar mass of 40.
(a) Write down the chemical symbol of this metal. (1)
(b) To which group does the metal belongs? (1)
9.2.3 Write down the chemical formula of an anhydrous salt above. (2)
9.3 The balanced equation below represents the chemical reaction, where
3 moles of sodium react with chlorine.
9.3.1 Calculate the mass of sodium chloride formed. (3)
9.3.2 Calculate the volume of chlorine at STP if it reacts with 3,5 moles of
sodium. (4)
9.4 A sample of sodium sulphate compound is found to contain 29% of sodium,
40,5% of sulphur and 30, 4% of oxygen.
Use relevant calculations to determine the empirical formula of this compound. (4)
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