Year 2 - A level

Question 1

What is needed for a dynamic equilibrium?

Answer 1

-Closed system, forward and backward reactions have same rate, conc. of products and reactions always constant(not equal)

Question 2

What is Le Chatilier’s principle?

Answer 2

When a change is applied to a system in dynamic equilibrium, the system shifts to oppose the change.

Question 3

What 4 things affect equilibrium?

Answer 3

• Temp. warmer shifts to endothermic
• Conc.
• Pressure
• Catalysts (no shift just rate increase)

Question 4

Conditions for Haber process?

Answer 4

450C at 200atm - compromise conditions with Iron catalyst

Question 5

Conditions for Hydration of ethene?

Answer 5

570k - compromise, 6000-7000kPa - high is good. Lots of steam not much ethene (cheaper)

Question 6

Conditions for methanol formation?

Answer 6

520k, 5000-10000kPa, catalyst copper, zinc oxide and aluminium oxide.

Question 7

Kc equation for aA + bB ⇌ cC dD

Answer 7

kc = [C]^c[D]^d/[A]^a[B]^b. If kc>1 eq lies to right as [Products]>[Reactants]

Question 8

Equation for partial pressure of a gas?

Answer 8

P(A) = no moles A/total moles x total pressure

Question 9

Kp equation for aA + bB ⇌ cC dD when gases

Answer 9

p(C)^c p(D)^d/p(A)^a p(B)^b

Question 10

What acronym do you use when working out moles in equilibrium?

Answer 10

ICE - initial , change , equilibrium

Question 11

What equation links ΔStotal, R and k?

Answer 11

ΔStotal = Rlnk when k is small, S is negative(unfeasible)

Question 12

What equation links ΔG, R, T and k?

Answer 12

ΔG = -RTlnk

Question 13

What is a Bronsted-Lowrey base?

Answer 13

A proton acceptor

Question 14

What is a Bronsted-Lowrey acid

Answer 14

A proton donor

Question 15

What does mono, di and tri-protic mean?

Answer 15

How many moles of protons per mole of acid.

Question 16

What makes an acid stronger?

Answer 16

More dissociation

Question 17

What is key about weak acids?

Answer 17

They only partially dissociate

Question 18

Equation for PH?

Answer 18

PH = -log10[H+]

Question 19

Equation for [H+] from PH?

Answer 19

[H+] = 10^-PH

Question 20

Ka equation for weak acids?

Answer 20

Ka = [H+][A-]/[HA] as [H+] = [A-] in weak also Ka = [H+]^2/[HA]

Question 21

Equation for pKa?

Answer 21

pKa = -log10Ka

Question 22

Equation for Kw?

Answer 22

Kw = [H+][OH-] = 1x10^-14

Question 23

Equation for pKw?

Answer 23

pKw = -log10Kw

Question 24

What is a buffer solution?

Answer 24

One that can oppose change in PH when small quatities of acid or alkali are added.

Question 25

Rearrange Ka equation for [H+]

Answer 25

[H+] = √Ka x [HA]

Question 26

What is enthalpy of neutralisation?

Answer 26

Energy change when one mole of water is formed from acid and base under standard conditions

Question 27

What indicatiors should be used for combinations of strong/weak acids and strong/weak alkalis?

Answer 27

Both strong/weak - litmus Strong acid, weak base - Methyl orange Strong base, weak acid - Phenopthalein

Question 28

Equation for Kin?

Answer 28

Kin = [H+][In-]/[HIn] at halfway to end point [In-] = [HIn] so [H+] = KIn

Question 29

On a PH curve when does pKa = PH?

Answer 29

Halfway to the end point(equivalence point) [In-] = [HIn] so they cancel

Question 30

What are the 2 stages of enthalpy of solution?

Answer 30

-Break up the lattice, hydrate the ions

Question 31

What is atomisation energy?

Answer 31

Energy change for formation of one mole of gaseous atom from element in standard states.

Question 32

What is 1st electron affinity?

Answer 32

Energy change for addition of one electron for each mole of atoms in gas phase.

Question 33

What does Theory vs Experiment show for lattice energy calculations?

Answer 33

Theory assume perfect spheres so difference between two values shows polarisation = covalancey. Big difference more covalent.