Equilibrium

Question 1

Kc formula

Answer 1

[Product]^no of moles / [reactant]^no mols

Question 2

Kc is constant providing

Answer 2

Temp is constant, products and reactants in same phase.

Question 3

High Kc means

Answer 3

Goes to completion

Question 4

Low Kc means

Answer 4

Reaction does not happen

Question 5

Kc = 1 means

Answer 5

Comparable amount of reactants and products

Question 6

What happens if increase conc.

Answer 6

Kc constant independent of conc. so conc of increased decreases and conc. unchanged increases

Question 7

What happens if increase pressure

Answer 7

Kc constant independent of pressure so mols of increased decreases and mols unchanged increases

Question 8

What happens to Kc if temp increase

Answer 8

Kc increase if enthalpy of reaction positive, otherwise decrease

Question 9

What happens to Kc if temp decrease

Answer 9

Kc increase if enthalpy of reaction negative, otherwise decrease

Question 10

How to calculate partial pressure

Answer 10

mol/total mols * total pressure

Question 11

Kp formula

Answer 11

PP of product^mols/PP of reactants^mols

Question 12

Heterogenous Kc

Answer 12

Conc. of pure solid/liquid taken to be 1 (because it is constant)

Question 13

Bronsted-Lowry definition of acid

Answer 13

Proton donor

Question 14

Bronsted-Lowry definition pf base

Answer 14

Proton acceptor

Question 15

Formula for pH

Answer 15

-log([H+])

Question 16

Kw

Answer 16

1 * 10^-14

Question 17

Ka formula for acid HA

Answer 17

= ([H+}[A-])/[HA]

Question 18

Strong acid Ka value

Answer 18

Very high,&raquo_space;1

Question 19

Weak acid Ka value

Answer 19

Very small «1

Question 20

Formula for finding pH of weak acid

Answer 20

Ka = [H+]^2 / [HA]

Question 21

pH curve of adding 0.1M 25cm-3 strong base to 0.1M 25 strong acid

Answer 21

Initial pH 1, Equivalence point at 25 where pH goes from 3 to 11, middle of this jump is 7. Asymptotic to 13

Question 22

pH curve, weak acid titrated with strong base

Answer 22

Starts at 3, buffer region until just before 7, pH equivalence at >7. Jump from 7 to 11. Asymptotic to 13.

Question 23

pH curve, strong base with strong acid

Answer 23

opposite of strong acid with strong base

Question 24

pH curve, weak base with strong acid

Answer 24

opposite of weak acid with strong base

Question 25

Finding pKa from titration line

Answer 25

Assume that weak acid has not dissociated in solution without base.
At half neutralisation (added 12.5), [HA] = [A-], therefore using Ka formula, they cancel and Ka = [H+]. So pKa = pH at half equivalence

Question 26

Diprotic acid pH curve

Answer 26

When adding strong base to weak acid, 2 equivalence points, one from >1 to 4, one to 5 to 11.

Question 27

How does an indicator work

Answer 27

HIn H+ + In-

HIn is a different colour to In-. Conc of H+ affects equilibrium

Question 28

Equivalence point

Answer 28

Same number of mols of acid and base

Question 29

End point

Answer 29

When indicator changes

Question 30

What makes successful indicator

Answer 30

End point = equivalence point

Colour change should be within pH jump for sharp colour change over 1 drop

Question 31

Diluting strong acid by 10 does what to pH

Answer 31

Decreases by 1

Question 32

Diluting weak acid by 10 does what to pH

Answer 32

Decreases by 0.5