In an experiment to determine the formula of a compound of iron and chlorine, chlorine gas was passed over heated iron. Mass of empty glass tube = 11.52 g; mass of glass tube and iron = 12.19 g; mass of empty bottle = 13.17 g; mass of bottle and compound of iron and chlorine after heating = 15.11 g.

1. aSuggest a safety precaution that should be used for this experiment, and give a reason. [2]
2. bExplain why chlorine is passed through anhydrous calcium chloride before reacting with the iron. [2]
3. cCalculate the mass of iron used in the experiment. [1]
4. dCalculate the mass of the compound of iron and chlorine in the experiment. [1]
5. eCalculate the mass of chlorine which reacted with the iron. [1]
6. fDeduce the empirical formula of the compound. [3]

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