Studied by 2 peopleHeat
the transfer of thermal energy from one object to another becuase of a temperature difference
How does heat spontaneously flow
hot to cold
When an object heats up, what happens to the particles?
They speed up; their kinetic energy increases
What is one way that heat flows?
The transfer of energy from hot particles colliding with cooler ones
True or false: high energy particle lose energy and low energy particles gain energy
true
What does thermal energy rely on?
Mass. Bigger → more mass → more thermal energy.
A cup of tea and a teapot can have the same temperature, but the teapot has more thermal energy because it has a bigger mass.
What are the two variables that are related to thermal energy?
Potential and kinetic energy of all the particles in an object
What does thermal energy depend on? (they are 3)
State (solid, liquid, gas), mass, temperature
Thermal energy also relies on temperature
A cold cup of tea and a hot cup of tea have the same mass, amount of particles, and are the same state, but since the hot cup has particles that are heated and moving, the hot cup has more thermal energy
Thermal expansion
an increase in the volume of a material due to a temperature increase
thermal contraction
a decrease in the volume of a material due to a temperature decrease
True or false: Gases expand more than liquids and solids, and liquids expand more than solids
true
Specific heat
the amount of heat needed to raise the temperature of one gram of a material by one degree celsius
relationship between a materials specific heat and how much the temperature rises
low specific heat = more temperature rise
low specific heat means low amount of heat needed to heat it up
high specific heat means high amount of energy needed to heat it up
Specific heat formula
Q =m *c * delta T
Q= amount of heat needed
m= mass
c= specific heat
delta t= change in temperature
An iron skillet has a mass of 500 grams. The specific heat of iron is 0.449 J/g°C. How much heat must be absorbed to raise the skillet’s temperature by 95 °C?
Q=m*c *delta T
Q= 500 g *0.449 J/g°C * 95 °C
Q= 21327.5 J
How much heat is needed to raise the temperature of 100 g of water by 85 °C?
Q= m* C* delta T
Q= 100g *4.18 J/g °C * 85 °C
Q= 35530 J
In setting up and aquarium the heater transfers 1200 kJ of heat to 75,000 g of water. What is the increase in the water’s temperature?
delta T= Q/m*c
delta T= 1,200,000 J/ 75,000g * 4.18 J/g°C
delta T= 3.8 °C
What mass of water with change its temperature by 3 °C when 525 J of heat is added to it?
M= Q/c* delta T
M= 525 J/ 3°C* 4.18 J/g°C
M= 42 g
Calorimeter
An instrument used to measure changes in thermal energy
What prinicple does a calorimeter use?
the lower a material’s specific heat is, the more its temperature rises when a given amount of energy is absorbed by a given mass
low specific heat= higher temperature when absorbes energy
The law of conservation of energy
thermal energy released by a test sample is equal to the thermal energy absorbed by its surroundings.
Note
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