1. As we exercise, our bodies metabolize glucose, converting it to CO2 and H2O,
ID: 904905 • Letter: 1
Question
1.
As we exercise, our bodies metabolize glucose, converting it to CO2 and H2O, to supply the energy necessary for physical activity. The simplified reaction is:
C6H12O6(aq)+6O2(g)
6CO2(g)+6H2O(l)+678 kcal(2840 kJ)
How many grams of water would have to be evaporated as sweat to remove the heat generated by the metabolism of 2 mol of glucose? (See Chemistry in Action: Regulation of Body Temperature on p. 195 in the textbook).
Express your answer to four significant figures and include the appropriate units.
2.For the production of ammonia from its elements, 3H2(g)+N2(g)2NH3(g),
H = -22 kcal/mol (-92 kJ/mol).
How much energy (in kilocalories and kilojoules) is released in the production of 0.690 mol of NH3?
Express your answers as integers separated by a comma.
Explanation / Answer
A) C6H12O6(aq) + 6O2(g) 6CO2(g) + 6H2O(l)
Moles of H2O formed by the metabolism of 2 moles of glucose = 12
Molar mass of H2O = 18 g/mole
Thus, mass of water to be evaporated = moles*molar mass = 12*18 = 12*18 =216 g
B) 3H2(g) + N2(g)2NH3(g)
Moles of NH3 formed = 0.69
2 moles of NH3 formation releases 22 kCal(92 kJ) heat
Thus, 0.69 moles of NH3 formation releases (22/2)*0.69 = 7.59 kcal (or, 31.74 kJ) heat
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