Making predictions using the reactivity series
2 marks · HardThallium (Tl) is a metal that is just below lead in the reactivity series. Predict whether thallium will react with dilute hydrochloric acid at room temperature. Explain your reasoning.
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Thallium will not react with dilute hydrochloric acid at room temperature because it is below hydrogen in the reactivity series, so it cannot displace hydrogen from the acid.
Also accept: Thallium will not react because it is less reactive than hydrogen.; No reaction because thallium is below hydrogen in the reactivity series.
Common mistakes: Saying thallium reacts because it is a metal.
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Marking points
M1 · 1 mark · Makes a correct prediction that thallium will not react with dilute hydrochloric acid.
A1 · 1 mark · States that thallium is below hydrogen in the reactivity series, or that it cannot displace hydrogen.
Worked solution
Thallium is below hydrogen in the reactivity series. Metals below hydrogen cannot displace hydrogen from acids, so thallium will not react with dilute hydrochloric acid.