PreACT Practice Test 12

Magnesium and hydrochloric acid

Magnesium (Mg) reacts with hydrochloric acid (HCl) to produce hydrogen gas (H₂). Students did 3 experiments on how fast this reaction occurs.

In each trial, 50.0 mL of HCl solution was poured into a flask, and the flask was placed in a water bath until the acid reached the trial temperature. A 0.050 g sample of Mg was then dropped into the flask, and the flask was immediately sealed with a stopper connected to a gas syringe. The volume of H₂ in the syringe was recorded 30 s later, and the time for all the Mg to disappear was also recorded. The HCl was in excess in every trial, and once all the Mg had reacted, each trial had produced a total of 49 mL of H₂.

Experiment 1. Mg ribbon was reacted at 20°C with HCl of different concentrations (Table 1).

Experiment 2. Mg ribbon was reacted with 1.00 M HCl at different temperatures (Table 2).

Experiment 3. Mg ribbon and Mg powder were each reacted with 1.00 M HCl at 20°C (Table 3).