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Ch.5 - Thermochemistry
All textbooksBrown 14th EditionCh.5 - ThermochemistryProblem 117
Chapter 5, Problem 117

It is estimated that the net amount of carbon dioxide fixed by photosynthesis on the landmass of Earth is 5.5 * 10^16 g/yr of CO2. Assume that all this carbon is converted into glucose. (b) Calculate the average rate of conversion of solar energy into plant energy in megawatts, MW (1 W = 1 J/s). A large nuclear power plant produces about 10^3 MW. The energy of how many such nuclear power plants is equivalent to the solar energy conversion?

Verified step by step guidance
1
Step 1: Determine the moles of CO2 fixed per year. Use the molar mass of CO2 (44.01 g/mol) to convert the given mass of CO2 (5.5 * 10^16 g/yr) into moles.
Step 2: Use the balanced chemical equation for photosynthesis: 6 CO2 + 6 H2O -> C6H12O6 + 6 O2. From this equation, determine the moles of glucose (C6H12O6) produced from the moles of CO2 calculated in Step 1.
Step 3: Calculate the energy stored in glucose. The combustion of glucose releases approximately 2800 kJ/mol. Use this value to find the total energy stored in the glucose produced per year.
Step 4: Convert the total energy from kilojoules to joules (1 kJ = 1000 J) and then to watts (1 W = 1 J/s). Since the energy is per year, convert the time to seconds (1 year = 365 days * 24 hours/day * 3600 seconds/hour).
Step 5: Calculate the equivalent number of nuclear power plants. Divide the average rate of conversion of solar energy (in MW) by the power output of a large nuclear power plant (10^3 MW) to find the number of such plants needed to match the solar energy conversion.
Related Practice
Open Question
Three hydrocarbons that contain four carbons are listed here, along with their standard enthalpies of formation: Hydrocarbon Formula ΔHfº (kJ/mol) Butane C4H10(g) -125 1-Butene C4H8(g) -1 1-Butyne C4H6(g) 165. (a) For Butane, calculate the molar enthalpy of combustion to CO2(g) and H2O(l). (kJ/mol) (b) For 1-Butene, calculate the molar enthalpy of combustion to CO2(g) and H2O(l). (kJ/mol) (c) For 1-Butyne, calculate the molar enthalpy of combustion to CO2(g) and H2O(l).
Textbook Question

A 201-lb man decides to add to his exercise routine by walking up three flights of stairs (45 ft) 20 times per day. Hefigures that theworkrequired to increasehis potential energy in this way will permit him to eat an extra order of French fries, at 245 Cal, without adding to his weight. Is he correct in this assumption?

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Textbook Question

Sucrose (C12H22O11) is produced by plants as follows: 12 CO2(g) + 11 H2O(l) → C12H22O11 + 12 O2(g) 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.

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Textbook Question

At 20 °C (approximately room temperature) the average velocity of N2 molecules in air is 1050 mph. (b) What is the kinetic energy (in J) of an N2 molecule moving at this speed?

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Textbook Question

Suppose an Olympic diver who weighs 52.0 kg executes a straight dive from a 10-m platform. At the apex of the dive, the diver is 10.8 m above the surface of the water. (a) What is the potential energy of the diver at the apex of the dive, relative to the surface of the water?

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Textbook Question

Suppose an Olympic diver who weighs 52.0 kg executes a straight dive from a 10-m platform. At the apex of the dive, the diver is 10.8 m above the surface of the water. (b) Assuming that all the potential energy of the diver is converted into kinetic energy at the surface of the water, at what speed, in m>s, will the diver enter the water?

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