7:16 #14
ANALYZE : question asks for a equilibrium shift resulting from a pressure change.
THEORY: LeChatelier : Increasing pressure goes to side of least moles OF GAS.
APPLY: the answer is choice 2, there are no gasses on the left, increasing
pressure goes there.
CaCO3 (s)   CaO (s) + CO2 (g)
7:16 #15
ANALYZE: Temp is increased changed on a system at equilibrium.
THEORY: Increasing temp reverses an exothermic reaction, forwards an
endothermic one.
APPLY. This reaction is endothermic (heat is written on the left)
2HBr + 72.7
kJ   H2 + Br2
HEAT
-2X
+X
+X
choice 1
Increase T, heat enters on left, EQ shifts to the right,
7:16 #16
ANALYZE : question asks for a equilibrium shift resulting from a increase of N2
change.
THEORY: LeChatelier : Increasing on one side shifts to the opposite side.
APPLY: N2 is on the left. Increasing it shifts to the right.
WHAT THE
SYSTEM WILL DO
AFTER STRESS IS
ADDED.
N2 (g) + O2 (g)  2 NO (g)
-X
-X
+ 2X
Increase N2, enters on left, EQ shifts to the right,
7:22 #34
ANALYZE : about an equilibrium pressure increase stress.
THEORY: LeChatelier : Increasing pressure drives to the side of least moles OF
GAS.
APPLY: moles on each side are equal, no effect! Ans C no change
N2 (g) + O2 (g)  2 NO (g)
1 mole + 1
=
2 moles
7:22 #35
ANALYZE : Heating a systemat equilibrium.
THEORY: Heating and exothermic reaction reverses it.
APPLY: This reaction will be reversed as you are heating exo reaction, heat enters
on the right and shifts left.
+2X
+X
- 2X : choice#4
HEAT
2 H2 (g) + O2 (g) 2 H2O (g) + HEAT
INCREASING T, heat enters on RIGHT, drives (LEFT).
7:22 #39
ANALYZE :Common Ion Effect, adding Cl-.
THEORY: LeChatelier : on right shifts left .
APPLY: In this reaction, Cl- enters on right, reaction shifts LEFT.
+2X
-X
- X : choice #2
AgCl(s) (g)   Ag+ (aq) + Cl- (aq)
INCREASING Cl- , enters RIGHT and shifts LEFT.
7:19 #9
ANALYZE: A + B  C + energy IS EXOTHERMIC, heat on right, BEING GIVEN OFF
(EVOLVED).
THEORY: In an EXOTHERMIC REACTION the products have LESS POTENTIAL
ENERY content then the REACTNTS, the rest is lost from the reaction as heat.
APPLY: In the reaction kinetics energy graph, the products will be at a LOWER
level than reactants. CHOICE 2
A+B
C
REACTANTS
PRODUCTS
7:19 #10
ANALYZE :Potential energy diagram
THEORY: The products are at lower energy level in an exothermic reaction.
APPLY: In the diagram below, the products are at a lower energy level than the
reactants, the difference is evolved as heat (kinetic energy). The reaction loses
potential energy as the kinetic energy of heat.
A+B
AB
REACTANTS
PRODUCTS
7:20 #16 and 17
ANALYZE : Given a potential energy graph
THEORY: If the products are at a higher energy level than the reactants, the
reaction is ENDOTHERMIC, heat is stored in the products as potential energy.
APPLY: The products are at a higher level in this graph, ENDOTHERMIC and
energy is gained (absorbed) by the system.
FORWARD
ACTIVATION
ENERGY
ACTIVATED
COMPLEX
A
PRODUCTS
REACTANTS
ANSWER: 16 IS ARROW A,
FORWARD ACTIVATION.
17 IS ENDOTHERMIC AND HEAT IS
ABSORBED CHOICE 4