P1 - 1.6 Specific Heat Capacity Flashcards
What is meant by internal energy
The total energy stored by the particles making up a substance or system
What 2 energy stores make up internal energy
Potential energy store
Kinetic energy store
What are some potential energy stores relating to internal energy
Gravitational
Elastic
True or False:
Potential energy stores are related to temperature
False
True or False:
Potential energy stores are not really related to temperature
True
What is an example of a kinetic energy store
The movement energy of particles
Which energy store is important to internal energy
Kinetic energy stores
How do we describe how energy is transferred when we heat an object
Kinetic energy is transferred to the surrounding via heat
When you increase the kinetic energy store how does this affect the internal energy
Internal energy is increased
What is temperature
A measure of the average internal energy of a substance
What piece of equipment can we use to measure internal energy
Thermometer
If we have a high internal energy how does this affect the thermometer
We will have a high temperature
How much energy does 1kg of water need to increase by 1 degrees Celsius
4200J
How much energy is required to increase 1kg of mercury by 1 degrees Celsius
139 degrees Celsius
What is specific heat capacity
The amount of energy needed to raise the temperature of 1kg of a substance by 1 degrees Celsius
Can also be referred to as how much energy is released as a substance cools
How much energy is given out when a 1kg water decreases by 1 degrees Celsius
4200J
What is the calculation for specific heat capacity
Change in internal temperature = mass x specific heat capacity x temperature change
What unit do we use for specific heat capacity
J/kg degrees Celsius
Find the final temperature of 800g of water at an initial temp of 20 degrees Celsius after 20kJ of energy has been transferred to it the specific heat capacity of the water is 4200J/kg degrees Celsius
Change in internal energy = mass x specific heat capacity x mass x temperature change
change in internal energy / mass x specific heat capacity = temperature change
20,000/(0.8x4200) = 5.95 degrees Celsius
5.95+20= 25.95 degrees Celsius
Or 26.0 if we rounded it to 3 sf
Why are our calculations technically not correct in real life when doing specific heat capacity calculations
Energy would be lost to the surroundings
How can we prevent energy from being lost in a specific heat capacity practical
Using insulations such as a lid
The particles in a s____ have kinetic energy because they are vibrating.
The particles in a solid have kinetic energy because they are vibrating.
The particles in a l_____ or gas have kinetic energy because they move around.
The particles in a liquid or gas have kinetic energy because they move around.
Temperature is a measure of the average kinetic energy of the p____ in a substance.
Temperature is a measure of the average kinetic energy of the particles in a substance.
A kettle with 0.05 kg of water was heated from 25 °C, to the boiling temperature of 100 °C.
The specific heat capacity of water is 4,200 J/kg°C
How much heat energy is required?
100-25 = 75
0.05 x 4200 x 75
= 15750
A beaker of water with a mass of 250g was heated until its internal energy increased by 21 kJ.
If the water’s original temperature was 24 °C, what is its final temperature?
(Specific heat capacity of water is 4,200 J/kg°C)
21kJ —> 21,000 J
M = 250g = 0.25kg
C= 4200J/kg degrees Celsius
21,000/ 0.25 x 4200 = 20 degrees Celsius
20+24 = 44 degrees Celsius
To heat 20g of aluminium by 1*C requires 18 J of energy. To heat the same amount of gold only requires 2.6 J.
Which element must have higher specific heat capacity?
(You don’t have to do any calculations)
Aluminium
A lump of gold with a mass of 20g was heated to 53 °C, and then allowed to cool down to 28 °C.
If gold’s specific heat capacity is 130 J/kg°C, how much internal energy did it lose in the cooling process?
ΔE = ?
m = 20 g = 0.02 kg
c = 130 J/kg°C
Δθ = 53 - 28 = 25 °C
ΔE = 0.02 x 130 x 25
= 65J
