Problem 95
Patients with a high body temperature are often given "alcohol baths." The heat of vaporization of isopropanol (rubbing alcohol) is \(665 \mathrm{~J} / \mathrm{g}\). How much heat is removed from the skin by the evaporation of \(190 \mathrm{~g}\) (about half a cup) of isopropanol?
Problem 96
What is the difference between an amorphous and a crystalline solid?
Problem 97
List three kinds of crystalline solids, and give an example of each.
Problem 99
The heat of fusion of sodium metal is \(2.6 \mathrm{~kJ} / \mathrm{mol}\). How much heat (in kilojoules) is required to melt \(262 \mathrm{~g}\) of sodium?
Problem 100
Use the kinetic-molecular theory to explain why gas pressure increases if the temperature is raised and the volume is kept constant.
Problem 101
Hydrogen and oxygen react according to the equation \(2 \mathrm{H}_{2}(g)+\mathrm{O}_{2}(g) \longrightarrow 2 \mathrm{H}_{2} \mathrm{O}(g)\). According to Avoga- dro's law, how many liters of hydrogen are required to react with \(2.5 \mathrm{~L}\) of oxygen at STP?
Problem 102
If \(3.0 \mathrm{~L}\) of hydrogen and \(1.5 \mathrm{~L}\) of oxygen at STP react to yield water, how many moles of water are formed? What gas volume does the water have at a temperature of \(100^{\circ} \mathrm{C}\) and 1 atm pressure?
Problem 103
Approximately \(240 \mathrm{~mL} / \mathrm{min}\) of \(\mathrm{CO}_{2}\) is exhaled by an average adult at rest. Assuming a temperature of \(37^{\circ} \mathrm{C}\) and 1 atm pressure, how many moles of \(\mathrm{CO}_{2}\) is this?
Problem 105
When fully inflated, a hot-air balloon has a volume of \(1.6 \times 10^{5} \mathrm{~L}\) at an average temperature of \(375 \mathrm{~K}\) and a pressure of 0.975 atm. Assuming that air has an average molar mass of \(29 \mathrm{~g} / \mathrm{mol}\), what is the density of the air in the hot-air balloon? How does this compare with the density of air at STP?
Problem 106
A \(10.0 \mathrm{~g}\) sample of an unknown gas occupies \(1.47 \times 10^{-2} \mathrm{~m}^{3}\) at a temperature of \(298 \mathrm{~K}\left(25^{\circ} \mathrm{C}\right)\) and a pressure of \(1.03 \times 10^{5} \mathrm{~Pa}\). How many moles of gas are in the sample? What is the molar mass of the gas?
