NAME:_______KEY_______________
Chemistry 150
Quiz 7
1. Write the equilibrium constant expression for the following reaction: (2 points)
6CO2(g) + 6H2O(g) ↔ C2H12O6(g) + 6O2(g)
K=
[C6H12O6][O2]6
[H2O]6[CO2]6
2. In the reaction
CH3Br + I- → CH3I + BrWe start the reaction with an initial CH3I concentration of 0.260 M. This
concentration increases to 0.840 M over a period of 1hour and 20 minutes. What is
the rate of the reaction (report the result as M/min). (3 points)
∆[CH3I] = [CH3I]end – [CH3I]beginning = (0.840 – 0.260) M = 0.580 M
∆t = 1 hour 20 minutes = 80 minutes
rate = ∆[CH3I]/ ∆t = 0.580 M/80 minutes = 0.00725 M/min
3. Here are equilibrium constants for two reactions. For each of them, determine if the
reaction favors products or reactants. ( 1 point each)
a. 0.0032
favors reactants
b. 3.2 x 105
favors products
4. Assume the following endothermic reaction is at equilibrium:
2H2S(g) ↔ 2H2(g) + S2(g)
Tell whether the position of the equilibrium will shift to the right or the left if we
a. Remove some H2. (1 point)
The reaction shifts to the right (products) to remake lost H2.
b. Increase the volume. (1 point)
An increase in volume is equal to a decrease in pressure. That favors more gas
molecules, therefore the reaction shifts to the right.
c. Decrease the temperature. (1 point)
The reaction shifts to the left, because heat is removed (in form of temperature)
and has to be remade.
POINTS:___10___(of 10)