Final answer:
If 3.0 moles of potassium metal react with hydrochloric acid, 1.5 moles of hydrogen gas will be produced based on the stoichiometry of the reaction.
Step-by-step explanation:
When potassium metal reacts completely with hydrochloric acid, hydrogen gas is produced according to the following balanced chemical equation:
2 K (s) + 2 HCl (aq) → 2 KCl (aq) + H₂ (g)
From the equation, we see that 2 moles of potassium (K) produce 1 mole of hydrogen (H₂). Therefore, to determine how many moles of hydrogen will form when 3.0 moles of potassium reacts, we can set up a ratio:
(3.0 moles K) × (1 mole H₂ / 2 moles K) = 1.5 moles H₂
Thus, 1.5 moles of hydrogen will form if 3.0 moles of potassium metal reacts completely with hydrochloric acid.