A student wants to identify an unknown alkali metal halide salt, MX. The student performs experiments on the alkali metal, M, and halogen, X2, which make up the salt.
The student’s results and observations are shown.
Test
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Observation
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The metal, M, is added to water
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The metal reacts violently with water producing a lilac flame
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The halogen, X2, is bubbled through a solution of the metal bromide, MBr
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The solution changes from colourless to orange
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The halide ion, X-, is added to a solution of silver ions
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A white precipitate forms
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What is the identity of the unknown alkali metal, MX?