Heat

Question 1

Considering heat capacities at constant volume, C_V, and constant pressure, Cp, which will generally be larger and why?

Answer 1

Picture:

C_V : For constant volume, use a system such as a sealed box.

C_P: For constant pressure use a closed system of gas, where a piston is positioned at the top.

Which will require more energy to change the temperature but keep the thermodynamic variable constant?

C_P since the energy is shared between the piston and atmosphere.

Question 2

Define Heat Capacity and give it’s dimensions.

Answer 2

A measurement of how heat needs to be supplied to change the temperature of an object.

C = dQ / dT, [C] = [JK^-1].

Question 3

The _______ ____ ________ is a Universal constant that we use to quantify the relationship between the properties of a gas.

Answer 3

ideal gas constant, R = 8.31447 JK^-1mol^-1 = N_A•k_B.

Question 4

Define Heat and give it dimensions.

Answer 4

Thermal Energy in Transit, [Heat] = [ml²t^-2] =[Joule].

Question 5

Define Molar Heat Capacity.

Answer 5

Molar Heat Capacity, C” = C’ x Molar Mass = C’ • mass • N_A, where C’ is the specific heat capacity and N_A is 6.022 x 10²³ “something” per mole.

[C”] = [JK^-1mol^-1].

Question 6

Define Specific Heat Capacity.

Answer 6

(Specific Heat Capacity) C’ = C / mass.

[C’] = [JK^-1kg^-1].

Question 7

____________ is the result of an irreversible process that takes place in homogeneous thermodynamic systems. A ___________process is a process in which energy (internal, bulk flow kinetic, or system potential) is transformed from some initial form to some final form; the capacity of the final form to do mechanical work is less than that of the initial form.

Answer 7

Dissipation, dissipative.

Question 8

Define thermal equilibrium.

Answer 8

Two physical systems are in thermal equilibrium if there is no net flow of thermal energy between them when they are connected by a path permeable to heat. Thermal equilibrium obeys the zeroth law of thermodynamics. A system is said to be in thermal equilibrium with itself if the temperature within the system is spatially uniform and temporally constant.

Question 9

T/F:

Thermal equilibrium implies Thermodynamic equilibrium.

Answer 9

False.

The converse is true.

Thermodynamic equilibrium: a state of a physical system in which it is in mechanical, chemical, and thermal equilibrium and in which there is therefore no tendency for spontaneous change

Thermal equilibrium: Temperature is constant (no changing in temperature).