Heat and Temperature Flashcards
are interrelated and sometimes the difference between the two can be a bit confusing
heat and temperature
deals with thermal energy
heat
is associated with molecular kinetic energy
temperature
is a measure of the average translational kinetic energy associated with the disordered motion of atoms and molecules.
temperature
property of a system which determines whether or not heat is transferred to or from an object.
temperature
can be described as the determination of the object’s sensation of warmth or coldness. in a qualitative manner
temperature
how “hot” or “cold” an object is
temperature
is transferred to the object (ex. stove heats pan)
heat
____ refers to the amount of energy in an object while ____is the measurement of hotness or coldness of an object.
heat
temperature
___depends on mass of the substance, however; ____does not depend on the quantity of matter.
heat
temperature
____can be measured directly using a thermometer but ___ cannot be measures directly with a device; mass, temperature and specific heat capacity must be known.
temperatuer
heat
_____ is the measure of total kinetic energy of all molecules in a substance while ____ is the measure of average kinetic energy of molecules in a substance.
heat
temperature
temperature scales (3)
fahrenheit
celsius
kelvin
classic English system for measuring temperature, created by Daniel Gabriel Fahrenheit in 1714
Fahrenheit
divides the difference between boiling point and freezing point of water into 180 degrees.
Fahrenheit
metric system of measuring temperature; devised by Anders Celsius in 1744; originally called degrees Centigrade
celsius
The scale is divided into 100 degrees between freezing point of water and boiling point of water
celsius
who devised Fahrenheit
Daniel Gabriel Fahrenheit
who devised Celsius
Anders Celsius
who devised Kelvin
William Thomson
devised by William Thomson (a.k.a. Lord Kelvin); temperature scale designed so that zero degrees K is defined as absolute zero
Kelvin
the temperature at which all thermal motion ceases based on the classical description of thermodynamics
absolute zero
formula of conversion of C to F
F = 1.8(oC) + 32
formula of conversion from F to C
C = oF-32/1.8
conversion of oC to K
K = C + 273.16
state that exists when two bodies that are in contact with each other no longer transfer heat between them.
thermal equilibrium
It means that an object has the same temperature throughout its interior.
thermal equilibrium
If two objects are in thermal equilibrium with a third, then they are in thermal equilibrium with each other.
zeroth law of thermodynamics
formula of zeroth law of thermodynamics
if TA=TC and Tb=Tc then Ta=Tb
When heat is given to a body one or more of the following may happen
increase in temperature
Increase in length ( area, volume)
Change in state of the body (ex. Solid to liquid)
change in chemical composition
change in electrical properties
change in color
is a consequence of change in the average separation between its constituent atoms or molecules.
thermal expansion
at ordinary temperatures, molecules vibrate with small amplitude but as the temperature ____, the amplitude increases causing an expansion of the whole object
increases
Experiments show that the increase in length or expansion of a solid depends of three factors:
material of which the solid is made
original length of material
change in temperature
to calculate the magnitude of an expansion, the equation is used:
ΔL = aLoΔT
The expansion of an ____ of a flat substance is derived from the linear expansion in both directions:
area
area expansion formula
ΔA = 2aAoΔT
three dimensions expand
volume expansion
gamma is equivalent to
2a
volume expansion formula
BVoΔT
for solids, B is equal to
3a
do execrises in thermal expansion
8
When energy is transferred to a substance by heating it, the temperature of the substance usually rises.
heat capacity
The amount of heat energy needed to raise the temperature of a substance is proportional to the temperature change and to the mass of the
substance.
heat capacity
specific heat capacity of water
4.186 J /oC Kg
amount of heat formula
CΔT = mcΔT
Q is positive if ΔT is positive; that is,
if heat is added to a system.
Q is negative if ΔT is negative; that is, if
heat is removed from a system
the amount of energy transferred via heating necessary to raise the temperature of a substance by one degree.
heat capacity
heat capacity per unit mass
specific heat or specific heat capacity
do practice problems 1-5
+1
if you double the thickness of a wall built from a homogenous material, the rate of heat loss for a given temperature difference across the thickness will
become one-half of its original value
how many calories are equal to one BTU
one calorie= 4.186 J
one BTU = 1054J
251.8 cal
on a sunny day at the beach, the reason the sand gets so hot and the water stays relatively cool is attributed to the difference in which property of the sand
specific heat
the reason ocean temperatures do not vary drastically is that
water has a relatively high specific heat
the heat required to change a substance from the solid to the liquid sate is referred to as the
heat of fusion
smallest unit of heat energy
joule
phase changes occur
as temp decreases
as temp increases
as temp remains the same
as temp remains the same
the amount of heat necessary to raise the temperature of 1 gram of water by 1oC is referred to as
calorie
measure of average kinetic energy
temperature
: If two systems are each in thermal equilibrium with a third system, then they are in thermal equilibrium with each other
what law
zeroth law
Energy cannot be created or destroyed; it can only be transferred or converted from one form to another
what law
law of conservation of energy (1st law of thermodynamics)
The total entropy of an isolated system can never decrease over time. Entropy tends to increase, leading systems to move towards thermodynamic equilibrium (maximum entropy).
what law of thermodynamics
second law of thermodynamics
as the temperature of a system approaches absolute zero, the entropy of the system approaches a minimum value.
what law of thermodynamics
third law of thermodynamics
