Making predictions using the reactivity series
4 marks · NormalMolybdenum (Mo) is a metal that lies between zinc and copper in the reactivity series.
Predict whether molybdenum will react with dilute hydrochloric acid at room temperature. Explain your answer.
Molybdenum metal is placed in a solution of silver nitrate.
State whether a reaction will occur and write a balanced equation for the reaction, if it occurs.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
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(a) No; molybdenum is below hydrogen in the reactivity series and does not react with dilute acids at room temperature.
(b) Yes; molybdenum will displace silver from silver nitrate. Equation: Mo(s) + 2AgNO3(aq) → Mo(NO3)2(aq) + 2Ag(s) · must show Correct prediction of displacement, Correct balanced equation
Common mistakes: Assuming all metals react with all acids; Incorrect displacement reactions
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · Correctly states that no reaction occurs with dilute hydrochloric acid.
B2 (a) · 1 mark · Explains that molybdenum is below hydrogen in the reactivity series.
B3 (b) · 1 mark · Correctly predicts a reaction will occur with silver nitrate.
B4 (b) · 1 mark · Provides correct balanced equation: Mo(s) + 2AgNO3(aq) → Mo(NO3)2(aq) + 2Ag(s)
Worked solution
a) Molybdenum will not react with dilute hydrochloric acid at room temperature because it is below hydrogen in the reactivity series. Metals below hydrogen do not displace hydrogen from acids.
b) Molybdenum is above silver in the reactivity series, so it can displace silver from its salt solution. The balanced equation is: