Thermal physics (lecture 1-2)

Question 1

Define temperature

Answer 1

• proportional to the translational kinetic energy per particle in a substance

Question 2

When can energy be exchanged between two objects?

Answer 2

When there is thermal contact; and temperature difference

Question 3

When does thermal equilibrium occur?

Answer 3

When 2 objects in thermal contact do not exchange heat

Question 4

What does the Zeroth law of thermodynamics state

Answer 4

If objects A and B are separately in Thermal equilibrium with a third object C, then A and B are in thermal equilibirum with one another

Question 5

true or false; 2 objects in thermal equilibrium are at the same temperature

Answer 5

true ; therefore if two objects have different temperature they cannot be in thermal equilibirum

Question 6

What is the ice point of water (Centigrade)

Answer 6

0 C

Question 7

What is the steam point of water (Centigrade)

Answer 7

100 C

Question 8

What is the freezing point of water (Farenheit)

Answer 8

32F

Question 9

What is the boiling point of water (Farenheit)

Answer 9

212

Question 10

What is a thermometer

Answer 10

a device used to measure the T(temperature) of a system

Question 11

How do you calibrate a thermometer

Answer 11

by placing it in contact with some atural systems that remain at constant T (mixture of ice and water; water and steam)

Question 12

What are the discrepencies of thermometers

Answer 12

Hg - cannot be used under -30C

alcohol cannot be used above 85C

Question 13

Define heat

Answer 13

internal energy transferred from one thing to another due to a temperature difference

• the transfer of energy across the boundary of a system due to the temperature difference between the system and its surroundings

Question 14

Describe the flow of heat

Answer 14

from high to low temperature ; until thermal equilibrium is established

Question 15

Define calorie (c); C mean kilocalories

Answer 15

is the amount of heat required to raise the temperature of one gram of water by one degree centigrade

Question 16

Define heat capacity (C)

Answer 16

the amount of heat required to raise the temperature by 1C

Question 17

equation of finding the amount of heat involved

Answer 17

Q = C delta T

Question 18

Define specific heat (c)

Answer 18

the specific heat capacity if a material is the amount of heat required to raise the temperature of 1kg of the material by 1C

Question 19

true or false; the specific heat capacity is essentially a measure of how INSENSITIVE a substance is to the addition of energy

Answer 19

true; thus the greater the specific heat of a substance, the more energy that must be added to cause a particular temperature change

Question 20

What is the specific heat capacity of water

Answer 20

4.18 kg/kj/K

Question 21

If Q and delta T are positive means that … the energy is transferred or released from the system?

Answer 21

transferred

Question 22

If Q nd delta T are negative this means that… the energy is transferred or released from the system?

Answer 22

released

Question 23

What is calorimetry

Answer 23

a technique for measuring specific heat capacity

Question 24

How is calorimetry performed?

Answer 24

• heating a material and adding it to a sample of water

Question 25

What is a bomb calorimeter

Answer 25

A bomb calorimeter is used to emasure the energy that is given out when one mole of a substance is completely burned in oxygen

Question 26

How is bomb calorimetry performed

Answer 26

• a known amount of a substance is placed in the crucible oxygen is added to 20atm (P)
• then the substance is ignited using heated wire
• as the calorimeter heats, it heats the water
• the rise in water temeperature is measured from this heat generated by the burning susbtance is calculated

Question 27

What is mathematical expression for the calorimetry problem

Answer 27

Q cold body = -Q hot body