W7 Concept of thermodynamics

Question 1

Zeroth Law of Thermodynamics

Answer 1

If two systems are in thermal equilibrium with a third system, the
two original systems are in thermal equilibrium with each other”

Question 2

What is potential energy?

Answer 2

Any form of stored energy

Question 3

What is kinetic energy?

Answer 3

Energy of moving objects

Question 4

What is the First Law of Thermodynamics?

Answer 4

Energy cannot be created or destroyed, only transformed, from one form to another

Question 5

Law of conservation of energy:

Answer 5

delta U = Q - W

where U= change in internal energy
Q- Heat added to system
W = Work done by the system

Question 6

What is meant by Adiabatic?

Answer 6

No heat transfer
Internal energy changes only for work done or received by the system

Question 7

What are the terms for constant volume and constant temperature?

Answer 7

Isovolumetric and isothermal

Question 8

What is the Second Law of Thermodynamics?

Answer 8

“The Universe is always moving towards maximum disorder”

Question 9

What is entropy (s) ?

Answer 9

A measure of disorder (dispersal in a system)

Question 10

∆s = sf – si

Answer 10

If there is an increase in the number of microstates, then Wf > Wi and the entropy of the system increases ∆S > 0

If there is a decrease in the number of microstates, then Wf < Wi and the entropy of the system decreases ∆S < 0

Question 11

Two Bulb Experiment:

Answer 11

Spontaneous process where gas expands to fill both bulbs equally, increasing entropy.

Question 12

Is the energy higher for solids or liquids?

Answer 12

Liquids
(dispersal is higher as molecules are more separated)
Entropy: Solid < Liquid < Gas

Question 13

Does increasing temperature affect entropy?

Answer 13

Yes- As temp inc, entropy inc as kinetic energy inc and therefore more dispersion

Question 14

What increases entropy?

Answer 14

Inc temp
Changing state
Mixing of particle types

Question 15

Why does entropy equal zero?
What temperature is absolute zero in ⁰C?

Answer 15

All vibrations and atomic movements
-273.15 ⁰C

Question 16

What does Gibbs free energy predict?

Answer 16

∆G: Predicts if the reaction is spontaneous or not (at constant T and P)

Question 17

When does a system come to equilibrium?

Answer 17

when it reaches its minimum Gibbs energy

Question 18

What is Dynamic Equilibrium:

Answer 18

Reactions do not stop
when equilibrium is reached. The forward and backwards reactions continue to occur at the same rate. The overall proportion of R and P does not change.

Question 19

What is the Equilibrium constant (K)

Answer 19

Describes the composition of a reaction
mixture when it comes to equilibrium

Question 20

Reaction Quotient Q:

Answer 20

Measure of the composition of the reaction mixture as the reaction progresses – not at equilibrium

Question 21

When is Q used?
When is K used?

Answer 21

Q= not at equilibrium
K= at equilibrium

Question 22

For info:

Answer 22

If ∆Gr < 0, Q < K then the forward reaction proceed
If ∆Gr > 0, Q > K then the reverse reaction proceeds
If ∆Gr = 0, Q = K then the system is at equilibrium