WEEK 4 (Thermodynamics) Flashcards
What is temperature a quantitative measure of?
“Hotness” or “coldness” of an object
What are the characteristics of heat?
- Heat is transferred from hot body to the colder body
- Heat can be transformed into work
- Heat is a change of internal energy
What is the Zeroth Law of Thermodynamics?
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
What does Thermal Equilibrium mean?
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
What are the characteristics of temperature?
- Temperature changes with transfer of heat
- Temperature is a measure of internal energy
What is Avogadro’s constant?
6.02 X 10^23
What does Avogadro’s constant mean?
1 mole of a substance contains 6.02 X 10^23 atoms or molecules
Boltzmann’s constant is the bridge between what?
Temperature and Energy
It shows that temperature and energy are linked
Define ‘Internal Energy’
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
Define “Heat”
The transfer of energy between a system and its environment due to a temperature difference between them
What are the units of measurement of heat?
Joule
What is the equation of heat capacity?
C = Q/T
Q - heat
T - temperature change
What is the equation of Specific Heat capacity?
C = Q/mT
Q - Heat
T- temperature change
M - mass
What is specific latent heat and what is its equation?
Transfer of heat without change of temperature
L = Q/m
What is the equation for work done on a gas?
W = -P x V
P - pressure throughout the gas
V - change in volume of the gas during the process
What is the first law of thermodynamics?
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
What are the different equations for the processes regarding the first law of thermodynamics?
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
What is ‘Enthalpy’?
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
Under which conditions can enthalpy change show heat flow during the process?
Isobaric conditions
What enthalpy equation shows heat flow during the process?
Change in H = (Hc + Hd) - (Ha + Hb)
Change in H < 0 exothermic reaction
Change in H > 0 endothermic reaction
What are the 3 main factors that produce and maintain the membrane potential?
Active transport, excess negative charge and concentration of ions
What equation is used to calculate membrane potential?
Goldman-Hodgkin-Katz equation
At the peak of an action potential the membrane potential is slightly ___________________ than the Na+ equilibrium potential
Less positive
What term describes the cell membrane potential of a neuron at rest?
Polarised
