Chapter 3: Thermodynamics

Question 1

temperature conversions

Answer 1

F = 9/5 C + 32

K = C + 273

Question 2

thermal expansion equation

Answer 2

ΔL =αLΔT

ΔL = change in lenght
α = coefficient of linear expansion
L = original lenght
ΔT = change in temperature

Question 3

volume expansion equation

Answer 3

ΔV = βVΔT

ΔV = change in volume
β = coefficient of volumetric expansion
L = original volume
ΔT = change in temperature

Question 4

First law of thermodynamics

Answer 4

ΔU = Q - W

ΔU = change in internal energy
Q = energy tranfered into the system
W = work done by the system

Question 5

heat gained or lost (with temperature change)

Answer 5

q = m c ΔT

c = specific heat of the substance
m = mass in Kg

Question 6

heat gained or lost (phase change)

Answer 6

q = mL

m = mass
q = heat
L = heat of tranformation or letent heat

Question 7

entropy and heat

Answer 7

ΔS = Qrev / T

ΔS = change in entropy
Qrev = heat gained or lost in a reversible processs
T = temperature in K

Question 8

second law of thermodynamics

Answer 8

ΔSuniverse = ΔSsystem + ΔSsurrounding > 0

Question 9

isothermal ΔU =0

Answer 9

Q = W

Question 9

adiabatic (Q = 0)

Answer 9

ΔU = - W

Question 9

isovolumetric or isochoric ( W = 0)

Answer 9

ΔU = Q

Question 10

work equations for a cylinder with contant preure and change nin volume

Answer 10

W = P ΔV

Question 11

0 degrees celsius

Answer 11

272 K

Question 12

100 degree C

Answer 12

373 K

Question 13

Zeroth law of thermodynamics.

Answer 13

When one objects in thermal equilibrium with another object and the second objects in thermal equilibrium with the third object, then the 1st and 3rd object are also in thermic equilibrium.

Question 14

Temperature

Answer 14

Differences in temperature determine the direction of heat transfer. Temperatures proportional to the average kinetic energy of a particle that makes up the substance. Heat moves spontaneously from materials that have higher temperature to materials that have lower temperature.

Question 15

Heat

Answer 15

refers to the transfer of thermal energy from hotter objects with higher temperature to a colder object with lower temperature. If no net heat flows between the objects in thermal contact, then we can say that their temperatures are equal and that they are in thermal equilibrium.

Question 15

Kelvin scale.

Answer 15

It defines as the zero reference point absolute 0, the theoretical temperature at which there is no thermal energy and sets the freezing point of water as 273K.

Question 15

Third law of thermodynamics.

Answer 15

States that the entropy of a perfectly organized crystal are absolute 00.

Question 16

Body temperature.

Answer 16

98.6 Fahrenheit or 37 Celsius.

Question 17

Thermal Expansion.

Answer 17

Rising temperatures cause an increase in length and falling temperatures cause a decrease in length. The amount of length changes the proportional to the origin length of the solid and the increasing temperature.

Question 18

Coefficient of linear expansion α

Answer 18

Constant that characterized how a specific material’s length changes.

Question 18

Coefficient of volumetric expansion β

Answer 18

Constant the characterizes how a specific materials volume changes as the temperature changes.

Question 19

Relationship between coefficient of volumetric expansion and coefficient of linear expansion.

Answer 19

Β = 3α

Question 20

Isolated systems.

Answer 20

Not capable of exchanging energy or matter with the surroundings. An example is a bomb calorimeter.

Question 21

Closed system.

Answer 21

Capable of exchanging energy but not matter with the surrounding.

Question 22

State functions.

Answer 22

Independent of the path taken to get to a particular equilibrium state. Some examples are pressure density, temperature, volume, enthalpy, internal energy, Gibbs free energy, entropy.

Question 22

Open system.

Answer 22

Can exchange both matter and energy with the environment.

Question 23

First law of thermodynamics.

Answer 23

States that the change in the total internal energy of a system is equal to the amount of energy transferred in the form of heat to the system minus the amount of energy transferred from the system in the form of work. The internal energy of a system can be increased by adding heat, doing work on the system, or some combination of both. Internal energy of a system will decrease when heat is lost from the system where work is performed by the system.

Question 24

Second law of thermodynamics.

Answer 24

Objects in thermal contact and not in thermal equilibrium will exchange heat energy such that the object with the higher temperature will give off the heat energy to the object with lower temperature until both objects have the same temperature at thermal equilibrium.

Question 25

Conduction.

Answer 25

The direct transfer of energy from molecule to molecule through molecular collision. There must be direct physical contact. Metals are described as the best heat conductors because metallic bonds contain a density of atoms embedded in a sea of electrons.

Question 26

Convection.

Answer 26

The transfer of heat by the physical motion of a fluid over a material. Only liquids and gases can transfer heat by this mean.

Question 27

Conversion factors between the units of heat.

Answer 27

1 Cal = 10^3 cal = 4184 J = 3.97 BTU

Question 27

Radiation.

Answer 27

Is a transfer of energy by electromagnetic waves.

Question 28

What is the specific heat of water?

Answer 28

1 cal/g.K

Question 29

Special types of thermodynamic processes.

Answer 29

Isothermal, which has constant temperature and therefore no change in internal energy, adiabatic, which has no heat exchange, and isovolumetric no change in volume and therefore no work accomplished.

Question 30

Entropy

Answer 30

Measure of the spontaneous dispersal of energy at a specific temperature. How much energy is spread out, or how widely spread out energy becomes in a process. The units of entropy are usually J/mol.K

Question 31

Natural processes and irreversibility.

Answer 31

When a hot object is brought into thermal contact with a cold object, the object will transfer heat in the energy to the code object until both are intermolecular Librium. This is a natural process and is also one that it would be described as irreversible. We are not surprised that the two objects eventually would reach a common temperature, but. You would be shocked if all of a sudden the hot object became hotter and the cold object became colder. This would be an unnatural process.