a.
The sun supplies energy at the rate of about 1.0 kilowatts persquare meter of earth (1 watt = 1 J/s). The plants in anagricultural field produce the equivalent of 20. kg of sucrose(C12H22O11) per hour per hectare (1 ha = 10,000 m2). Assume thatsucrose is produced by the reaction given below.
12 CO2(g) + 11 H2O(l) C12H22O11(s) + 12 O2(g) ?H = 5640 kJ
Calculate the percentage of sunlight used to produce the sucrose,that is, determine the efficiency of photosynthesis.
%
b.
On Easter Sunday, April 23, 1983, nitric acid spilled from a tankcar near downtown Denver, Colorado. The spill was neutralized withsodium carbonate.
2 HNO3(aq) + Na2CO3(s) 2 NaNO3(aq) + H2O(l) + CO2(g)
Calculate ?H° for this reaction.
kJ
Approximately 5.0 104 gal nitric acid was spilled. Assume that theacid was an aqueous solution containing 50.0% HNO3 by mass with adensity of 1.42 g/cm3. How much sodium carbonate was required forcomplete neutralization of the spill? (?Hf° for NaNO3(aq) = -467kJ/mol.)
g
How much heat was evolved?
kJ
According to The Denver Post for April 4,1983, authorities fearedthat dangerous air pollution might occur during the neutralization.Considering the magnitude of ?H°, what was their majorconcern?
c.
A piece of chocolate cake contains about 400 Calories. Anutritional Calorie is equal to 1000 calories (thermochemicalcalories), which is equal to 4.184 kJ. How many 9-inch-high stepsmust a 180 pound man climb to expend the 400 Cal from the piece ofcake? Assume that the energy used to climb steps is the same as theenergy required to lift a mass against the force of gravity,namely: PE = mgh, where m is the mass of the object lifted inkilograms, g is the gravitational constant (9.8 m/s2), and h is theheight the object is lifted in meters.
steps
a.
The sun supplies energy at the rate of about 1.0 kilowatts persquare meter of earth (1 watt = 1 J/s). The plants in anagricultural field produce the equivalent of 20. kg of sucrose(C12H22O11) per hour per hectare (1 ha = 10,000 m2). Assume thatsucrose is produced by the reaction given below.
12 CO2(g) + 11 H2O(l) C12H22O11(s) + 12 O2(g) ?H = 5640 kJ
Calculate the percentage of sunlight used to produce the sucrose,that is, determine the efficiency of photosynthesis.
%
b.
On Easter Sunday, April 23, 1983, nitric acid spilled from a tankcar near downtown Denver, Colorado. The spill was neutralized withsodium carbonate.
2 HNO3(aq) + Na2CO3(s) 2 NaNO3(aq) + H2O(l) + CO2(g)
Calculate ?H° for this reaction.
kJ
Approximately 5.0 104 gal nitric acid was spilled. Assume that theacid was an aqueous solution containing 50.0% HNO3 by mass with adensity of 1.42 g/cm3. How much sodium carbonate was required forcomplete neutralization of the spill? (?Hf° for NaNO3(aq) = -467kJ/mol.)
g
How much heat was evolved?
kJ
According to The Denver Post for April 4,1983, authorities fearedthat dangerous air pollution might occur during the neutralization.Considering the magnitude of ?H°, what was their majorconcern?
c.
A piece of chocolate cake contains about 400 Calories. Anutritional Calorie is equal to 1000 calories (thermochemicalcalories), which is equal to 4.184 kJ. How many 9-inch-high stepsmust a 180 pound man climb to expend the 400 Cal from the piece ofcake? Assume that the energy used to climb steps is the same as theenergy required to lift a mass against the force of gravity,namely: PE = mgh, where m is the mass of the object lifted inkilograms, g is the gravitational constant (9.8 m/s2), and h is theheight the object is lifted in meters.
steps
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