8. Thermochemistry

Which of the following is the largest quantity of energy?

Two positively charged particles are first brought close together and then released. Once released, the repulsion between particles causes them to move away from each other. (a) This is an example of potential energy being converted into what form of energy?

Convert between energy units. c. 4.99 * 103 kJ to kWh

Suppose that a person eats 2387 Calories per day. Convert this amount of energy into each unit. c. kWh

A particular frost-free refrigerator uses about 745 kWh of electrical energy per year. Express this amount of energy in each unit. c. Cal

The enthalpy of evaporation of water is 40.67 kJ/mol. Sunlight striking Earth's surface supplies 168 W per square meter (1 W = 1 watt = 1 J/s). (a) Assuming that evaporation of water is due only to energy input from the Sun, calculate how many grams of water could be evaporated from a 1.00 square meter patch of ocean over a 12-h day

Use of the British thermal unit (Btu) is common in some types of engineering work. A Btu is the amount of heat required to raise the temperature of 1 lb of water by 1°F. Calculate the number of joules in a Btu.

A watt is a measure of power (the rate of energy change) equal to 1 J/s. (b) An adult person radiates heat to the surroundings at about the same rate as a 100-watt electric incandescent light bulb. What is the total amount of energy in kcal radiated to the surroundings by an adult over a 24 h period?

Assume that the nutritional content of an apple-say, 50 Cal (1 Cal = 1000 cal) - could be used to light a light bulb. For how many minutes would there be light from each of the following? (a) A 100-watt incandescent bulb (1 W = 1 J/s)

The solar power striking Earth every day averages 168 watts per square meter. The highest ever recorded electrical power usage in New York City was 13,200 MW. A record established in July of 2013. Considering that present tech- nology for solar energy conversion is about 10% efficient, from how many square meters of land must sunlight be collected in order to provide this peak power? (For compar- ison, the total area of New York City is 830 km2.)

(b) A particular chip snack food is composed of 12% protein, 14% fat, and the rest carbohydrate. What percentage of the calorie content of this food is fat?

(a) A serving of a particular ready-to-serve brown & wild rice meal contains 4.5 g fat, 42 g carbohydrate, and 4.0 g protein. Estimate the number of calories in a serving.

Answer the following questions. (e) A gallon of ice cream contains exactly 32 servings, and each serving has 165 Calories, of which 30.0% are derived from fat. How many Calories derived from fat would you consume if you ate one half of a gallon of ice cream?

A bag of Hershey's Kisses contains the following information: Serving size: 9 pieces = 41 g Calories per serving: 230 Total fat per serving: 13 g (c) How many Calories are in one Hershey's Kiss?

Sucrose (C12H22O11) is produced by plants as follows: 12 CO21g2 + 11 H2O1l2¡ C12H22O11 + 12 O21g2 H = 5645 kJ About 4.8 g of sucrose is produced per day per square meter of the earth's surface. The energy for this endothermic reaction is supplied by the sunlight. About 0.1 % of the sunlight that reaches the earth is used to produce sucrose. Calculate the total energy the sun supplies for each square meter of surface area. Give your answer in kilowatts per square meter 1kW>m2 where 1W = 1 J>s2.