Black powder was used as a propellant for fireworks for centuries. One of the components of black powder is potassium nitrate (KNO₃). Black powder containing 1 mol of KNO₃ releases 289 kJ of heat during combustion. The molar mass of KNO₃ is 101 g/mol. How much heat is released if a firework contains 250 g of KNO₃?

Question

Quizplus · Accepted Answer

First, calculate the number of moles in 250 g of KNO₃: $ \frac{250 \, \text{g}}{101 \, \text{g/mol}} = 2.475 \, \text{moles} $. Since 1 mole releases 289 kJ, $ 2.475 \, \text{moles} \times 289 \, \text{kJ/mole} = 715.275 \, \text{kJ} $, which rounds to 715 kJ.

Black Powder Was Used as a Propellant for Fireworks for Centuries