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### Chapter 11 problem 115

Posted: Tue Nov 22, 2016 11:54 am
11.115 The overall photosynthesis reaction is
6 CO 2 (g) ! 6 H 2 O(l) S C 6 H 12 O 6 (aq) ! 6 O 2 (g), and
’H# " !2802 kJ. Suppose that the reaction is at equilibrium.
State the effect that each of the following changes will have
on the equilibrium composition (tends to shift toward the
formation of reactants, tends to shift toward the formation of
products, or has no effect). (a) The partial pressure of O 2 is
increased. (b) The system is compressed. (c) The amount of CO 2
is increased. (d) The temperature is increased. (e) Some of the
C 6 H 12 O 6 is removed. (f) Water is added. (g) The partial pressure
of CO 2 is decreased.

### Re: Chapter 11 problem 115

Posted: Tue Nov 22, 2016 12:22 pm
Imagine a seesaw. Reactants on left, products on right. Removing something from either side will cause the other side to be heavier and pull the seesaw down. To reach equilibrium, it needs more weight on the lighter side, which represents which side it favors. An imbalance forces the heavier side to convert to the lighter side to reach a stable equilibrium that is "balanced" in weight.

A positive delta H means heat is on the right side because the reaction requires energy input.

a. If more O2 is added, the seesaw will weigh more on the right side and will want to swing left to reach equilibrium. Favor reactants.
b. If compressed, there will be no effect on the system because both sides have the same concentration of gases (6).
c. If CO2 is increased, the reaction will favor products. Same explanation as a.
d. If temperature is increased, the reaction will favor products. Same explanation as a.
e. If C 6 H 12 O 6 is removed, the reaction will favor reactants. Same explanation as a.
f. Adding or removing liquids or solids do not affect equilibrium because pure solids / liquids do not have a concentration.
g. If partial pressure CO2 is decreased, the reaction will favor reactants. Same explanation as a.