1/30 heat work and enthalpy

Question 1

what is a state function

Answer 1

they depend only on the initial and final states, the path between does not matter

it is path independent

Question 2

what is a path function

Answer 2

they depend on the path between initial and final states

Question 3

what are some examples of path functions

Answer 3

work and heat

Question 4

what are some examples of state functions

Answer 4

internal energy is a state function

Question 5

what is heat capacity

Answer 5

heat capacity is the heat needed to raise the temperature of a substance by 1C

Question 6

is heat capacity an extensive or intensive property

Answer 6

heat capacity is an extensive property, it depends on the amount of substance

Question 7

is molar heat capacity intensive or extensive

Answer 7

it is intensive, it is the heat capacity divided by the number of moles

Question 8

what is the Cp,m

Answer 8

the constant pressure heat capacity

Question 9

what is the Cv,m

Answer 9

the constant volume heat capacity

Question 10

when we heat at a constant volume, what does the heat contribute to?

Answer 10

it only contributes to the change in temperature

Question 11

when we heat a container with constant pressure, what does the heat contribute to

Answer 11

the input of heat contributes to work being done to expand the gas and to increase the temperature

Question 12

why is the heat capacity at a constant pressure larger than the heat capacity at a constant volume

Answer 12

since the heat input is being used to do work and increase the temperature at constant pressure, it requires more heat to increase the temperature to the same temperature as the constant volume box

Question 13

when increasing the temperature of a liquid or solid, why can we say the heat capacities of the constant volume and constant pressure are relatively the same

Answer 13

when increasing the temperature of a liquid or a solid, there is virtually no change in the volume

Question 14

under constant pressure

Answer 14

the heat is equal to the change in enthalpy

Question 15

under constant volume

Answer 15

the heat is equal to the change in internal energy

Question 16

when the system is giving off heat, the enthalpy is

Answer 16

exothermic and negative

Question 17

when the system is absorbing heat. the enthalpy is

Answer 17

endothermic and positive

Question 18

enthalpy is a state or path function?

Answer 18

state function

Question 19

what is the change in internal energy and change in enthalpy proportional to

Answer 19

they are proportional to changes in temperature

Question 20

if temperature is constant, what does this mean about the internal energy and enthalpy

Answer 20

it means the change in ∆T is zero, so the ∆U is zero and ∆H is zero