An excess of potassium hydroxide is treated with 1.4 L of dry hydrogen bromide gas measured at STP. What is the mass of potassium bromide formed?

Question

Quizplus · Accepted Answer

At STP, 1 mole of gas occupies 22.4 L. Therefore, 1.4 L of HBr is 1.4/22.4 = 0.0625 moles. The reaction between KOH and HBr is 1:1, so 0.0625 moles of KBr is formed. The molar mass of KBr is approximately 119 g/mol, so the mass of KBr formed is 0.0625 moles * 119 g/mol = 7.4 g.

An Excess of Potassium Hydroxide Is Treated with 1