WEEK 4 (Thermodynamics)

Question 1

What is temperature a quantitative measure of?

Answer 1

“Hotness” or “coldness” of an object

Question 2

What are the characteristics of heat?

Answer 2

• Heat is transferred from hot body to the colder body
• Heat can be transformed into work
• Heat is a change of internal energy

Question 3

What is the Zeroth Law of Thermodynamics?

Answer 3

The zeroth law of thermodynamics states that if two bodies are each in thermal equilibrium with a third body, they are also in equilibrium with each other

Question 4

What does Thermal Equilibrium mean?

Answer 4

Thermal equilibrium means that when two bodies are brought into contact with each other and separated by a barrier that is permeable to heat, there will be no transfer of heat from one to the other

Question 5

What are the characteristics of temperature?

Answer 5

• Temperature changes with transfer of heat
• Temperature is a measure of internal energy

Question 6

What is Avogadro’s constant?

Answer 6

6.02 X 10^23

Question 7

What does Avogadro’s constant mean?

Answer 7

1 mole of a substance contains 6.02 X 10^23 atoms or molecules

Question 8

Boltzmann’s constant is the bridge between what?

Answer 8

Temperature and Energy

It shows that temperature and energy are linked

Question 9

Define ‘Internal Energy’

Answer 9

The energy associated with the microscopic components of a system— the atoms and molecules of the system. The internal energy includes kinetic and potential energy associated with the random translational, rotational, and vibrational motion of the particles that make up the system and any potential energy bonding the particles together

Question 10

Define “Heat”

Answer 10

The transfer of energy between a system and its environment due to a temperature difference between them

Question 11

What are the units of measurement of heat?

Answer 11

Joule

Question 12

What is the equation of heat capacity?

Answer 12

C = Q/T

Q - heat
T - temperature change

Question 13

What is the equation of Specific Heat capacity?

Answer 13

C = Q/mT

Q - Heat
T- temperature change
M - mass

Question 14

What is specific latent heat and what is its equation?

Answer 14

Transfer of heat without change of temperature

L = Q/m

Question 15

What is the equation for work done on a gas?

Answer 15

W = -P x V

P - pressure throughout the gas
V - change in volume of the gas during the process

Question 16

What is the first law of thermodynamics?

Answer 16

If a system undergoes a change from an initial state to a final state where Q is the energy transferred to the system by heat and W is the work done on the system, the change in the internal energy of the system is given by U = Q + W
U - change in thermal energy

Q > 0 when energy is transferred into the system
W > 0 when work is done on the system

Question 17

What are the different equations for the processes regarding the first law of thermodynamics?

Answer 17

Isobaric processes:
P = constant W=pV U=Q-W

Isothermal processes:
T = constant U=0 Q=W

Isovolumetric processes:
V=constant W=0 U=Q

Adiabatic processes:
Q=0 U=W

Question 18

What is ‘Enthalpy’?

Answer 18

The state variable of system which may be used to characterise chemical bond energies and heat of chemical reactions

H=U+pV

If p=constant
Change in H = Q

Question 19

Under which conditions can enthalpy change show heat flow during the process?

Answer 19

Isobaric conditions

Question 20

What enthalpy equation shows heat flow during the process?

Answer 20

Change in H = (Hc + Hd) - (Ha + Hb)

Change in H < 0 exothermic reaction
Change in H > 0 endothermic reaction

Question 21

What are the 3 main factors that produce and maintain the membrane potential?

Answer 21

Active transport, excess negative charge and concentration of ions

Question 22

What equation is used to calculate membrane potential?

Answer 22

Goldman-Hodgkin-Katz equation

Question 23

At the peak of an action potential the membrane potential is slightly ___________________ than the Na+ equilibrium potential

Answer 23

Less positive

Question 24

What term describes the cell membrane potential of a neuron at rest?

Answer 24

Polarised