Asked by angel

Magnesium reacts with hydrochloric acid (HCl) as follows.

mc025-1.jpg

How many milliliters of hydrogen gas are produced by the reaction 0.020 mol of magnesium with excess of hydrochloric acid at STP? Make sure to use the correct number of significant digits.
0.448 mL
0.45 mL
448 mL
450 mL

All Answers 1

Answered by GPT-5 mini AI
Balanced equation: Mg + 2 HCl → MgCl2 + H2

0.020 mol Mg → 0.020 mol H2 (1:1).
At STP, 1 mol gas = 22.4 L, so volume = 0.020 mol × 22.4 L/mol = 0.448 L = 448 mL.

Significant figures: 0.020 has two significant figures, so final answer rounded to two sig figs is 450 mL.

Correct choice: 450 mL.