Equilibrium

Question 1

What is equal at equilibrium?

Answer 1

Rate of forward and rate of reverse reactions

Question 2

What chemicals can be included in an equilibrium constant expression?

Answer 2

Gases and aqueous

NO SOLIDS OR LIQUIDS

Question 3

When writing a K or Q expression in terms of concentrations, you must use

Answer 3

Brackets
Ex. [A]

Question 4

When writing a K or Q expression in terms of pressures, you must use

Answer 4

partial pressures
Ex. P_A

Question 5

If K > 1, then the _________ are favored at equilibrium.

Answer 5

Products

Question 6

If 0 < K < 1, then the _________ are favored at equilibrium.

Answer 6

Reactants

Question 7

When K is a large number (usually greater than 1000), we can treat the reaction as if it is

Answer 7

going to completion and using up the limiting reactant.

Question 8

When K is a very small number (usually less than 0.0001), we can assume that

Answer 8

a negligible amount of reactants are used.

Note: You CANNOT assume that no products are formed. Even if it is a tiny amount of reactants, it’s still significantly greater than 0.

An example of this is when K_a is used in weak acid equilibrium.

Question 9

When you reverse a reaction, what do you do to K?

Answer 9

1/K

Question 10

When you triple the coefficients of a reaction, what do you do to K?

Answer 10

K³

Question 11

When you add two reactions together, what do you do to their Ks?

Answer 11

Multiply them together

Question 12

If Q < K, then the reaction is proceeding to produce more _________.

Answer 12

Products

Question 13

If Q > K, then the reaction is proceeding to produce more _________.

Answer 13

Reactants

Question 14

If Q < K, then the forward reaction is _______ than the reverse reaction.

Answer 14

Faster

Question 15

If Q > K, then the forward reaction is _______ than the reverse reaction.

Answer 15

Slower

Question 16

Effect of catalysts on equilibrium

Answer 16

Does not disturb equilibrium or cause shifting of reaction

Question 17

Effect of adding inert (unreacting) gas on equilibrium

Answer 17

Does not disturb equilibrium or cause shifting of reaction

Question 18

Effect of adding a solid on equilibrium (not dissolving to be aqueous)

Answer 18

Does not disturb equilibrium or cause shifting of reaction

Question 19

Decreasing the volume of gases at equilibrium will cause the reaction to shift to the side of the reaction

Answer 19

that has less moles of gas to decrease pressure back down.

Note: If equal number of moles of gas on each side, equilibrium will not be disturbed.

Question 20

How T and K are related for endothermic rxns

Answer 20

Increasing T causes K to increase

Question 21

How T and K are related for exothermic rxns

Answer 21

Increasing T causes K to decrease

Question 22

What is the only way that K changes?

Answer 22

Changing temperature

Question 23

When adding water to dilute an aqueous-phase reaction, the reaction will shift to the side

Answer 23

with more moles of aqueous chemicals

Question 24

Adding a common ion to a solution at equilibrium will cause the reaction to shift _______________ the side with the common ion.

Answer 24

Away from

Question 25

*K*_sp for insoluble compound made of 2 ions

Answer 25

*K*_sp = s²

Question 26

*K*_sp for insoluble compound made of 3 ions

Answer 26

*K*_sp = 4s³

Question 27

s is defined as the molar solubility (how much solid dissolves) of a solid with units of

Answer 27

mol/L OR *M*

Question 28

The larger the value of s for an insoluble solid, the ________ soluble the solid is.

Answer 28

more

Question 29

When comparing two solids made up of an equal number of ions, the solid with a ________ *K*_sp is more soluble.

Answer 29

Greater

Question 30

If *Q*_sp is ______ than *K*_sp, a precipitate will form

Answer 30

Greater