Thermal physics (lecture 1-2) Flashcards
Define temperature
- proportional to the translational kinetic energy per particle in a substance
When can energy be exchanged between two objects?
When there is thermal contact; and temperature difference
When does thermal equilibrium occur?
When 2 objects in thermal contact do not exchange heat
What does the Zeroth law of thermodynamics state
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
true or false; 2 objects in thermal equilibrium are at the same temperature
true ; therefore if two objects have different temperature they cannot be in thermal equilibirum
What is the ice point of water (Centigrade)
0 C
What is the steam point of water (Centigrade)
100 C
What is the freezing point of water (Farenheit)
32F
What is the boiling point of water (Farenheit)
212
What is a thermometer
a device used to measure the T(temperature) of a system
How do you calibrate a thermometer
by placing it in contact with some atural systems that remain at constant T (mixture of ice and water; water and steam)
What are the discrepencies of thermometers
Hg - cannot be used under -30C
alcohol cannot be used above 85C
Define heat
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
Describe the flow of heat
from high to low temperature ; until thermal equilibrium is established
Define calorie (c); C mean kilocalories
is the amount of heat required to raise the temperature of one gram of water by one degree centigrade
Define heat capacity (C)
the amount of heat required to raise the temperature by 1C
equation of finding the amount of heat involved
Q = C delta T
Define specific heat (c)
the specific heat capacity if a material is the amount of heat required to raise the temperature of 1kg of the material by 1C
true or false; the specific heat capacity is essentially a measure of how INSENSITIVE a substance is to the addition of energy
true; thus the greater the specific heat of a substance, the more energy that must be added to cause a particular temperature change
What is the specific heat capacity of water
4.18 kg/kj/K
If Q and delta T are positive means that … the energy is transferred or released from the system?
transferred
If Q nd delta T are negative this means that… the energy is transferred or released from the system?
released
What is calorimetry
a technique for measuring specific heat capacity
How is calorimetry performed?
- heating a material and adding it to a sample of water
What is a bomb calorimeter
A bomb calorimeter is used to emasure the energy that is given out when one mole of a substance is completely burned in oxygen
How is bomb calorimetry performed
- 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
What is mathematical expression for the calorimetry problem
Q cold body = -Q hot body
