Topic 23 Entropy Gibbs Free Energy Change

Question 1

Entropy

Answer 1

The measure of randomness or disorder of a system

Question 2

Surroundings (other than reactant and products)

Answer 2

-solvent
-the air
-reaction vessel

Question 3

Diffusion

Answer 3

The random movement and random collision of particles

Question 4

Standard conditions

Answer 4

-10^5Pa
-298K

Question 5

Unit for entropy

Answer 5

JK^-1mol^-1

Question 6

Entropy is great if

Answer 6

-There are more ways of arranging energy in a molecule or atom
-There are more ways of arranging the molecules or atoms in a given volume

Question 7

Entropy changes- state changes (gas-liquid-solid)- why?

Answer 7

-When gas condenses into a liquid or a liquid changes to a solid
-the entropy decreases because because the particles are going from a more disordered state to a more ordered state. There are also fewer ways arranging the energy.

Question 8

Entropy changes in concentrated aqueous solutions of salts which have highly charged ions may have considerable order in the solvent due to several hydration layers around these ions- explain?

Answer 8

-When salts which have highly charged ions are dissolved
-The particles are going from a more disordered state to a more ordered state. There are also fewer ways arranging the energy.

Question 9

Entropy in exothermic reactions (surroundings)

Answer 9

-Energy released to the surroundings increases the number of ways of arranging the energy
-Hence, there is likely to be an increase in entropy and an increased probability of the chemical change occurring spontaneously

Question 10

Entropy in endothermic reactions (surroundings)

Answer 10

-Energy absorbed from the surroundings decreases the number of ways of arranging the energy
-So there is likely to be a decrease in entropy and a decreased probability of chemical change occurring spontaneously

Question 11

Total entropy change equal to

Answer 11

Entropy of system + entropy of surroundings

Question 12

Entropy of system equal to

Answer 12

Sum of entropy of products - Sum of entropy of reactants

Question 13

Entropy of surroundings equal to

Answer 13

(minus) enthalpy of reaction / temperature

Question 14

We multiply the value of enthalpy of reaction by ** to find entropy of surroundings

Answer 14

by 1000, because of kJ equals 1000J

Question 15

When reached equilibrium entropy is?

Answer 15

Zero

Question 16

Temperature effect on entropy(surroundings)

Answer 16

• An increase in temperature makes the entropy change of the surroundings less negative or more positive
  -A decrease in temperatures makes the entropy change in the surroundings less negative or more positive

Question 17

Gibbs free energy changes is equal to

Answer 17

Enthalpy of change reaction - Temperature*Entropy of system

Question 18

For a reaction to be feasible Gibbs free energy must be

Answer 18

negative, or equal to zero

Question 19

Sum of Gibbs free energy change of reaction equals to

Answer 19

Sum of Gibbs free energy change products- Sum of Gibbs free energy change reactants