Heat, Temperature, and Thermodynamics

Question 1

The sum of the potential and kinetic energies of the molecules in a substance is called the _____ ______ of the substance

Answer 1

internal energy

Question 2

Heat definition

Answer 2

the kinetic energy of molecules transferred from a warmer substance to a cooler one

Question 3

Temperature definition

Answer 3

the average kinetic energy of the molecules in a substance

Question 4

Kelvin Temperature Equation

Answer 4

K = C + 273

Question 5

Conversion between joules and calories

Answer 5

1 calorie = 4.186 joules

Question 6

Linear Thermal Expansion

Answer 6

the increase in any one dimension of the solid. The change in length deltaL is proportional to the original length and the change in temperature of the solid

Question 7

Volume thermal expansion

Answer 7

an increase in the volume of the solid. The change in volume deltaV is proportional to the original volume of the solid and its change in temperature

Question 8

Three ways of transferring heat:

Answer 8

conduction, convection, and radiation

Question 9

Conduction definition

Answer 9

The transfer of heat directly through a material, or by actual contact between two materials. Metals are typically good heat conductors. Insulators are not. By placing an iron skillet on a fire, heat is transferred by conduction to the handle of the skillet

Question 10

Convection definition

Answer 10

The transfer of heat by the bulk movement of a fluid (liquid or gas). Water heated in a pan is an example of heat transfer by convection

Question 11

Radiation definition

Answer 11

The process by which heat is transferred by electromagnetic waves. Microwave ovens and a roaring campfire are both examples of radiation

Question 12

Heat absorbed or released by an object as a result of a change in temperature equation:

Answer 12

Q = mcdeltaT, (calories) where Q is the symbol for heat, m is the mass of the object, deltaT is the change in temperature and is equal to the final temperature minus the initial temperature, and c is the specific heat of the substance. Note that if the mass is in kg, the temperature in C, and the specific heat in kilocalorie/kg, the answer will be in kilocalories.

Question 13

Specific heat c definition

Answer 13

a proportionality constant that gives an indication of the ease with which one can raise the temperature of something; the larger it is, the larger the amount of heat required to raise its temperature a certain number of degrees, and also the more heat is released if it cools by a certain number of degrees.

Question 14

Heat capacity definition

Answer 14

the heat needed to raise the temperature of the object as a whole by 1 C or 1K

Question 15

Heat equation for phase changes:

Answer 15

Q = mL, where m is the mass of the substance undergoing the phase change and L is the heat of transformation, the value of which depends on both the substance and the particular process we are talking about: vaporization, sublimation, or fusion (melting)

Question 16

Three types of systems:

Answer 16

isolated, closed, and open

Question 17

Isolated system definition

Answer 17

A system that cannot exchange energy or matter with the surroundings, like a well-insulated thermos flask

Question 18

Closed system definition

Answer 18

A system that can exchange energy but not matter with the surroundings, like a test tube with a stopper in it

Question 19

Open system definition

Answer 19

A system that can exchange both matter and energy with the surroundings, like a pot of boiling water allowing water vapor to escape into the air

Question 20

First law of Thermodynamics

Answer 20

Law of conservation of energy. The change in the internal energy deltaU of a system is equal to the heat Q added to the system minus the work W that a system does: deltaU = Q - W (J). If work is done ON a system, W is negative and deltaU = Q + W

Question 21

If work is done ON a system, its energy would ______

Answer 21

increase

Question 22

If work is done BY the system, its energy would ______

Answer 22

decrease

Question 23

Heat engine definition

Answer 23

any device that uses heat to perform work.

Question 24

Three essential factors of a heat engine:

Answer 24

1. Heat is supplied to the engine at a high temperature from a hot reservoir 2. Part of the input heat is used to perform work 3. The remainder of the input heat that did not do work is exhausted into a cold reservoir, which is at a lower temperature than the hot reservoir

Question 25

Percent efficiency (%epsilon) equation

Answer 25

%epsilon = 100* Work/Qhot (the ratio of the work done to the amount of input heat)

Question 26

The second law of thermodynamics

Answer 26

law of entropy. All spontaneous processes proceeding in an isolated system lead to an increase in entropy