Chemical Thermodynamics

Question 1

What does log10 mean (with example)?

Answer 1

How many times do we have to multiply 10 by itself to get our desired number
E.g. log10[100]= 2
as 10x10=100

Question 2

What does ln mean?

Answer 2

Natural logarithm
Rather than log10, it is 10e, where e is Euler’s number

Question 3

What is Euler’s number?

Answer 3

2.718

Question 4

What is the reverse of ln(x)?

Answer 4

e^x

Question 5

What are the 3 types of systems?

Answer 5

• Open system
• Closed system
• Isolated system

Question 6

What is an open system?

Answer 6

System that allows transfer of mass and energy

Question 7

What is a closed system?

Answer 7

Systems that allows transfer of heat, but not mass (e.g. sealed tube)

Question 8

What is an isolated system?

Answer 8

System that does not allow transfer of mass or energy

Question 9

What does kinetic energy come from?

Answer 9

Motion

Question 10

What does potential energy come from?

Answer 10

Position of objects (e.g. position of atoms due to forces of attraction/repulsion)

Question 11

What is the first law of thermodynamics?

Answer 11

The total energy of the Universe is constant.
Energy cannot be created or destroyed, only converted

Question 12

What is a state function?

Answer 12

A property whose value does not depend on the path taken.
The value is independent of the path taken

Question 13

What is a path function?

Answer 13

A property whose value does depend on the path taken to get from initial to final state

Question 14

Examples of state function:

Answer 14

• Internal energy
• Entropy
• Gibbs
• Enthalpy

Question 15

Examples of path function:

Answer 15

• Work done
• Heat transfer

Question 16

What is the second law of thermodynamics?

Answer 16

Heat never flows spontaneously from a cold body to a hot body.
Any spontaneous change much be accompanied by an increase in the entropy of the Universe

Question 17

What is important to remember when doing calculations involving energy and/or temp

Answer 17

Standard SI units:
Temp = Kelvin
Energy = Joules

Question 18

What is latent heat?

Answer 18

During state changes, the temperature will cease to increase despite energy being put in.
This energy being put in, when you don’t see a change in temperature, is known as latent heat

Question 19

Why does the temperature not increase for latent heat?

Answer 19

The energy is being used to push particles further apart

Question 20

What is latent heat for solid to liquid known as?

Answer 20

Latent heat of fusion/melting

Question 21

What is latent heat for liquid to gas known as?

Answer 21

Latent heat of vaporisation

Question 22

What is the third law of thermodynamics?

Answer 22

The entropy of a pure crystalline substance at absolute zero is 0.
This represents a perfect crystal; nothing is in motion.

Question 23

How can molar Gibbs energy be used as a measure of phase stability?

Answer 23

The most stable phase of a material always has the lowest molar energy

Question 24

How does the state with the lowest molar Gibbs energy change as pressure increase?

Answer 24

As pressure increases, the state with the lowest molar Gibbs energy goes from:
gas -> liquid -> solid

Question 25

What are standard conditions?

Answer 25

Temperature = 298K
Pressure = 1 atm
Concentration = 1 mol L-1