Chapter 5, Problem 85E

Propane, ${\text{C}}_3{\text{H}}_8$, is a hydrocarbon that is commonly used as a fuel.

(a) Write a balanced equation for the complete combustion of propane gas.

(b) Calculate the volume of air at 25 °C and 1.00 atmosphere that is needed to completely combust 25.0 grams of propane. Assume that air is 21.0 percent O₂ by volume. (Hint: we will see how to do this calculation in a later chapter on gases−for now use the information that 1.00 L of air at 25 °C and 1.00 atm contains 0.275 g of °2 per liter.)

(c) The heat of combustion of propane is −2,219.2 kJ/mol. Calculate the heat of formation, $\Delta H_{\text{f}}^{°}$ of propane given that $\Delta H_{\text{f}}^{°}$ of ${\text{H}}_2\text{O}\left(l\right)=-285.8$ kJ/mol and $\Delta H_{\text{f}}^{°}$ of ${\text{CO}}_2\left(g\right)=-393.5$ kJ/mol.

(d) Assuming that all of the heat released in burning 25.0 grams of propane is transferred to 4.00 kilograms of water, calculate the increase in temperature of the water.