Problem 22
The enthalpy of combustion of isooctane \(\left(\mathrm{C}_{8} \mathrm{H}_{18}\right)\) one of the many hydrocarbons in gasoline, is \(5.45 \times 10^{3} \mathrm{kJ} / \mathrm{mol} .\) Calculate the enthalpy change per gram of isooctane and per liter of isooctane \((d=0.688 \mathrm{g} / \mathrm{mL})\)
Problem 24
Calculate the energy used, in kilojoules, to power a 100-watt lightbulb continuously over a 24 -hour period. How much coal would have to be burned to provide this quantity of energy, assuming that the enthalpy of combustion of coal is \(33 \mathrm{kJ} / \mathrm{g}\) and the power plant has an efficiency of \(35 \% ?\) [ Electrical energy for home use is measured in kilowatt hours (kW-h). One watt is defined as \(1 \mathrm{J} / \mathrm{s},\) and \(1 \mathrm{kW}\) -h is the quantity of energy transferred when 1000 watt is dispensed over a 1.0 -hour period.
Problem 27
A parking lot in Los Angeles receives an average of \(2.6 \times 10^{7} \mathrm{J} / \mathrm{m}^{2}\) of solar energy per day in the summer. (a) If the parking lot is \(325 \mathrm{m}\) long and \(50.0 \mathrm{m}\) wide, what is the total quantity of energy striking the area per day? (b) What mass of coal would have to be burned to supply the quantity of energy calculated in (a)? (Assume the enthalpy of combustion of coal is \(33 \mathrm{kJ} / \mathrm{g} .)\)
Problem 28
Your home loses energy in the winter through doors, windows, and any poorly insulated walls. A sliding glass door \((6 \mathrm{ft} \times 6.5 \mathrm{ft} \text { with } 0.5\) inch of insulating glass ) allows \(1.0 \times 10^{6} \mathrm{J} / \mathrm{h}\) to pass through the glass if the inside temperature is \(22^{\circ} \mathrm{C}\left(72^{\circ} \mathrm{F}\right)\) and the outside temperature is \(0^{\circ} \mathrm{C}\left(32^{\circ} \mathrm{F}\right) .\) What quantity of energy, expressed in kilojoules, is lost per day? Assume that your house is heated by electricity. How many kilowatt-hours of energy are lost per day through the door? (See Study Question 24 for the definition of a kilowatt- hour.
Problem 29
Some fuel-efficient hybrid cars are rated at 55.0 miles per gallon of gasoline. Calculate the energy used to drive 1.00 mile if gasoline produces \(48.0 \mathrm{kJ} / \mathrm{g}\) and the density of gasoline is \(0.737 \mathrm{g} / \mathrm{cm}^{3} .(1.00 \mathrm{gal}=3.785 \mathrm{L})\)
Problem 30
Microwave ovens are highly efficient, compared to other cooking appliances. A 1100 -watt microwave oven, running at full power for 90 seconds, will raise the temperature of 1 cup of water \((225 \mathrm{mL})\) from \(20^{\circ} \mathrm{C}\) to \(67^{\circ} \mathrm{C} .\) As a rough measure of the efficiency of the microwave oven, compare its energy consumption with the energy required to raise the water temperature.
Problem 33
Which of the following is not a limitation for the use of hydrogen as a fuel? (a) An inexpensive method of producing hydrogen (b) A practical means of storing hydrogen (c) Hydrogen is explosive (d) A distribution system (hydrogen refueling stations)
Problem 34
Which of the following statements is true? (a) Fuel cells are widely used in automobiles. (b) \(\mathrm{H}_{2}\) is readily available as a transportation fuel. (c) Petroleum is a mixture of hydrocarbons. (d) Methane hydrate can never be developed as a commercial energy resource.
Problem 37
Which of the species listed below is not a greenhouse gas? (a) \(\mathrm{H}_{2} \mathrm{O}\) (b) \(\mathrm{CH}_{4}\) (c) \(\mathrm{CO}_{2}\) (d) \(\mathrm{O}_{2}\)
Problem 38
What is the correlation between ocean \(\mathrm{pH}\) and atmospheric \(\mathrm{CO}_{2} ?\) (a) As \(\mathrm{CO}_{2}\) increases, the pH decreases. (b) As \(\mathrm{CO}_{2}\) increases, the pH also increases. (c) As \(\mathrm{CO}_{2}\) increases, the pH does not change.
