Oceans

Question 1

Lattice enthalpy

Answer 1

The enthalpy change that accompanies the formation of one mole of an ionic compound from its gaseous ions under standard conditions

Question 2

Ionic bonding

Answer 2

the electrostatic attraction between oppositely charged ions

Question 3

Enthalpy change of hydration

Answer 3

the enthalpy change that takes place when one mole of isolated gaseous ions is dissolved in water, forming one mole of aqueous ions under standard conditions - always exothermic

Question 4

Enthalpy change of solvation

Answer 4

the enthalpy change that takes place when one mole of isolated gaseous ions is dissolved in a solvent other than water

Question 5

hydrogen bonding

Answer 5

a strong dipole dipole attraction between an electron deficient hydrogen atom on one molecule and a lone pair of electrons on a highly electronegative atom on a different molecule

Question 6

enthalpy change of solution

Answer 6

the enthalpy change that takes place when one mole of a compound is completely dissolved in water under standard conditions - can be exothermic or endothermic

Question 7

strong acid

Answer 7

an acid that completely dissolves in solution

Question 8

weak acid

Answer 8

an acid that partially dissolves in solution

Question 9

strong base

Answer 9

a base that completely dissociates in solution

Question 10

buffer

Answer 10

a system that minimises pH changes on addition of small amounts of an acid or base

Question 11

solubility product

Answer 11

Ksp - represents the conditions for equilibrium between a sparingly soluble product and its saturated solution

Question 12

entropy

Answer 12

a measure of the number of ways of arranging molecules and distributing energy

Question 13

Equation - enthalpy change of solution

Answer 13

ΔHsol = ΔHhyd (cation) + ΔHhyd (anion) - ΔHle

Question 14

calculating pH of a strong acid

Answer 14

1) write out an ionisation expression for the acid
2) use molar ratios to deduce the [H+]
3) substitute into pH = -log [H+]

Question 15

Calculating pH of a weak acid

Answer 15

1) write out the Ka expression for the weak acid
2) assume that [H+] is the same as [A-]
3) rearrange to make [H+] the subject
4) substitute into pH = -log [H+]

Question 16

calculating pH of a strong base

Answer 16

1) write out an ionisation expression for the base
2) use molar ratios to deduce the [OH-]
3) substitute [OH-] into Kw, Kw= [H+][OH-]
4) rearrange to make [H+] the subject
5) substitute into pH = -log [H+]

Question 17

calculating pH of a buffer solution

Answer 17

1) write out the Ka expression for the buffer
2) recalculate the concentrations of HA and A- in the new total volume of the buffer C1V1=C2V2
3) rearrange to make [H+] the subject, Ka * ([HA]/[A-]) = [H+]
4) substitute in Ka and concentrations of A- and HA to calculate [H+]
5) substitute into pH = -log [H+]

Question 18

calculating solubility product

Answer 18

Ksp(CaCO3) = [Ca2+][CO32-]
Ksp = [Ca2+]^2
√Ksp = [Ca2+]

Question 19

Enthalpy change of reaction equation

Answer 19

Q=mc ΔT
ΔH = (-Q/1000)/n

Question 20

Total entropy equation

Answer 20

ΔtotalS = S of products - S of reactants

Question 21

Entropy of surroundings

Answer 21

ΔsurrS = ΔH/T

Question 22

Calculating the minimum temperature a reaction is feasible at

Answer 22

ΔtotalS = ΔsysS + (-ΔH/T)
0= ΔsysS + (-ΔH/T)
T = ΔH/ΔsysS