all equations HL

Question 1

calculating overall entropy from that of reactants and products

Answer 1

dS = all S (products) - all S (reactants)

Question 2

calculating enthalpy change for enthalpy changes of formation

Answer 2

dH = dHf (products) - dHf (reactants)

Question 3

calculating free Gibb’s energy from Gibb’s energy of products and reactants

Answer 3

dG = dGf (products) - dGf (reactants)

Question 4

calculating enthalpy change from enthalpy changes of combustion

Answer 4

dH = dHc (reactants) - dHc (products)

Question 5

calculating free Gibb’s energy form Gibb’s energy of combustion

Answer 5

dG = dGc (reactants) - dGc (products)

Question 6

relationship between enthalpy of formation, lattice enthalpy and all the other enthalpies

Answer 6

dHlots = dH (LE) + dHf [with lattice enthalpy having a positive sign]

Question 7

relationship between half-life and rate constant for first order reactions

Answer 7

t1/2 = ln2 : k

Question 8

relationship between dissociation constant of weak acid and concentration of weak acid

Answer 8

Ka = [H+] [A-] : [HA]

Question 9

relationship between dissociation constant of weak base and concentration of weak base

Answer 9

Kb = [OH-] [BH+] : [B]

Question 10

calculating the concentration of hydrogen ions of a weak acid

Answer 10

[H+] = sq root Ka x [HA]

Question 11

calculating the concentration of hydroxide ions of a weak pure base

Answer 11

[OH-] = sq root Kb x [B]

Question 12

Henderson-Hasselbalch equation for buffers formed by acids and their salts

Answer 12

pH = pka + log(10) [A-] : [HA]

Question 13

Henderson-Hasselbalch equation for buffers formed by bases and their salts

Answer 13

pOH = pKb + log(10) [BH+] : [B]

Question 14

standard cell electrode potential of feasible reactions where the sign of the smaller electrode potential was reversed

Answer 14

E(cell) = E(1) + E(2)

Question 15

Gibb’s free energy from cell electrode potential and number of electrons

Answer 15

dG = n x F x E(cell)

Question 16

relationship between charge and current in electrolysis

Answer 16

Q = I x t (t in seconds)

Question 17

relationship between number of electrons flowing, charge and Faraday’s constant

Answer 17

n = Q : F