Ch4 Enthalpy, entropy and free energy

Question 1

enthalpy change of hydration

Answer 1

enthalpy change when 1 mol of gaseous ions is completely hydrated in water

Question 2

enthalpy change of solution

Answer 2

enthalpy change when 1 mol of ionic solvent dissolves in water

Question 3

sum of enthalpies of hydration

Answer 3

lattice enthalpy + enthalpy change of solution

Question 4

Entropy

Answer 4

amount of energy not absorbed or released in thermal form in a reaction

Question 5

solids entropy

Answer 5

movement of particles and energy contained- is restricted to vibration of particles

more restricted, lower the molar entropy

Question 6

Liquids entropy

Answer 6

particles have greater freedom of movement so high

Question 7

Gas entropy

Answer 7

Highest as has greatest freedom of moevment
Greater disorder, more flexible dispersion of energy

Question 8

Entropy increase

Answer 8

1. solid becomes liquid
2. liquid becomes gas
3. temperature rises
4. solid dissolved in liquid to form solution
5. reaction produces products with greater degree of freedom

Question 9

Entropy assumption

Answer 9

When temperature is o degrees, entropy is 0

Question 10

Entropy change

Answer 10

entropy of products - entropy of reactants

Δ S tot = Δ S system + Δ S surroundings

Question 11

Gibbs free energy

Answer 11

enthalpy change of reaction - (temp x entropy change)

Δ H -TΔ S

Question 12

Reaction Feasability

Answer 12

If free energy is negative, reaction is feasible

Question 13

Free energy at equilibrium

Answer 13

Should be 0
So temperature = Δ H/Δ S