chapter 8 - extent of chemical reactions

Question 1

equilibrium

Answer 1

rate of forward reaction = rate of backward reaction
- closed system
- constant temp

Question 2

equilibrium law

Answer 2

Qc = [P] y [Q]z/ [A]w[B]x
products / reactants
xA + xB - yP + zQ
units: replace M for every R and P (do not right 1, write no units)
the larger the K the closer to equilibrium

Question 3

calculating k using stoichiometry

Answer 3

ICEE tabel
1. mol values from table
2. use stoichiometry to calculate change values and mol at equilibrium
3. use change to work out missing amounts
4. use concentration to work out K

Question 4

Le Chatelier’s principles

Answer 4

when a change is made to a system at equilibrium, the system will adjust to partially oppose the change

Question 5

adding reactant

Answer 5

effect - increase in conc of reactant
oppose - decrease con of reactants
how - equilibrium moves to right, making more products

Question 6

removing reactant

Answer 6

e - decrease in conc of reactants
o - increase conc of reactant
h - equilibrium moves to the left, making more reactants

Question 7

adding product

Answer 7

e - increase in conc of product
o - decrease in cocn of product
h - equilibrium moves to left, making more reactants

Question 8

removing product

Answer 8

e - decrease in conc of product
o - increase in conc of product
h - equilibrium moves to right, making more products

Question 9

decreasing volume

Answer 9

e - increse in pressure/ conc of reactants and products
o - decrease pressure in system
h - equilibrium moves in direction that makes less particles

Question 10

increasing volume

Answer 10

e - decrease in pressure/ conc of reactants and products
o - increase pressure in system
h - equilibrium moves in direction that makes more particles

Question 11

changing the temperature

Answer 11

• only change that will effect k
• permanent
• deltaH influences direction

Question 12

exothermic

Answer 12

temp increased
e - adds heat (adding product)
o - use up heat (remove product)
h - equilibrium moves to left (endothermic direction), makes more reactants
temp decreased
e - remove heat (removes product)
o - make more heat (make products)
h - equilibrium moves to right (exothermic direction), makes more products

an exothermic reaction is favoured (more products made) by decreasing temp

Question 13

endothermic

Answer 13

temp increased
e - adds heat (adding reactant)
o - us up heat (use up reactants)
h - equilibrium moves to the right (exothermic direction), makes more products
temp decreased
e - removes heat (removes reactants)
o - make more heat (make more reactants)
h - equilibrium moves to left (endothermic direction), makes more reactants

an exothermic reaction is favoured (more products made) by increased the temp

Question 14

catalyst

Answer 14

does not change position of equilibrium, just allows it ti be reached faster