Final answer:
To find the grams of hydrogen gas produced when 2.12 g of potassium reacts with hydrochloric acid, we use stoichiometry and the balanced chemical equation. The correct answer is 0.74 g of hydrogen gas.
Step-by-step explanation:
To find the grams of hydrogen gas produced when 2.12 g of potassium reacts with sufficient hydrochloric acid, we need to use balanced chemical equations and stoichiometry. The balanced chemical equation for the reaction is:
2K + 2HCl → 2KCl + H2
This means that 2 moles of potassium (K) react with 2 moles of hydrochloric acid (HCl) to produce 1 mole of hydrogen (H2). Using the molar mass of potassium and the molar ratio from the balanced equation, we can calculate the grams of hydrogen produced:
2.12 g K * (1 mole K / 39.10 g K) * (1 mole H2 / 2 moles K) * (2.016 g H2 / 1 mole H2) = 0.73 g H2
Therefore, the correct answer is 0.74 g (option b).