Question

Zn(s)+2 HCl(aq)→ZnCl2(aq)+H2(g)

Zn(s) reacts with HCl(aq) according to the equation shown above. In trial 1 of a kinetics experiment, a 5.0g piece of Zn(s) is added to 100mL of 0.10MHCl(aq). The rate of reaction between Zn(s) and HCl(aq) is determined by measuring the volume of H2(g) produced over time. In trial 2 of the experiment, 5.0g of powdered Zn(s) is added to 100mL of 0.10MHCl(aq). Which trial will have a faster initial rate of reaction and why?

Answer 1

Trial 2, which involves powdered zinc, will have a faster initial rate of reaction compared to Trial 1 with a single piece of zinc, due to the larger surface area of the powdered zinc allowing for more immediate reactions with hydrochloric acid.

Step-by-step explanation:

When comparing the rate of reaction between solid zinc metal and hydrochloric acid (HCl), the form of the zinc significantly affects the rate at which hydrogen gas (H2) is produced. In the context of the provided reaction:

Zn(s) + 2 HCl(aq) → ZnCl2(aq) + H2(g)

Trial 1 uses a single piece of zinc whereas Trial 2 uses powdered zinc. The surface area available for a reaction greatly influences the rate. Powdered zinc has a much larger surface area compared to a single piece of zinc, which allows more zinc atoms to be in contact with the hydrochloric acid at the same time. Therefore, Trial 2 would exhibit a faster initial rate of reaction because the powdered zinc provides a greater surface area for the hydrochloric acid to react with.