Qrtr 4 final

11 In which of the following reactions involving gases would the forward reaction be favored by an
increase in pressure?
A A + B ​⇄​AB
B A + B ​⇄​ C + D
C 2A + B ​⇄​ C + 2D
D AC ​⇄​ A + C
According to LeChatelier's principle regarding pressure, an equilibrium will shift to the side of a
reaction with less mass in order to accommodate for the change in pressure. Answer A is the only
answer where there is 1.) an unequal mass on either side, and 2.) where the forward reaction would
be favored. In A, A+B composes more mass than AB and so the reaction would be altered to
accommodate for the production of more AB to account for the change in pressure.
4HCl​ (g)​
+ O​ 2​(g)​
​⇄​ 2H​ 2​
O​ (l)​
+ 2Cl​ 2​(g)​
+ 113 kJ
12 Which action will drive the reaction to the right?
A heating the equilibrium mixture
B adding water to the system
C decreasing the oxygen concentration
D increasing the system’s pressure
Because there is more mass on the left, the right side of the equation will accommodate in
some way to maintain equilibrium. In this case, that would be to increase the pressure in the system
because it will promote the forward reaction.
NO​ 2​(g)​
+ CO​ (g)​
​⇄​ NO​ (g)​
+ CO2​ (g)
13 The reaction shown above occurs inside a closed flask. What action will shift the reaction to the
left?
A pumping CO gas into the closed flask
B raising the total pressure inside the flask
C increasing the NO concentration in the flask
D venting some CO​ 2​
gas from the flask
By increasing the concentration of NO in the closed flask, it promotes the conversion of the
reactant to product on the left. The more of this product is made, the more it will promote the
decomposition of the product back into the reactant. In a roundabout way. increasing the
concentration NO will promote a backward reaction because eventually it causes a larger mass of
product (left side)
NH​ 4​
Cl​ (s)​
+ heat ​⇄​ NH​ 3​(g)​
+ HCl​ (g)