Kinetic-Molecular
Theory
Theory
Specific Heat
States of Matter
Change of State
Thermodynamics
100
Which Sample of gas contains molecules with the smallest average speed?
Sample A - 250 K
Sample B - 225 K
Sample C - 273 K
Sample D 290 K
Sample B, because it has the lowest temperature.
100
What is specific heat?
the amount of heat energy that it takes to raise the temperature of 1 gram of a specific substance by 1 degree Celsius
100
What is the state of matter if: IF<KE
Gas
100
List all the places on the graph that you would use the equation Q=mCΔT to calculate the heat.
1 - heating up ice
3 - heating up liquid
5 - heating up gas
100
What is a good word to describe entropy?
Disorder
200
Which sample has the lowest temperatue?
Sample A: 1.5x104 J
Sample B: 5.06 x 104 J
Sample C: 2.73 x 103 J
Sample D: 5.10 x 103 J
Sample C because it has the lowest Kinetic Energy
200
What is the equation to calculate specific heat?
Q = mC△T
Q = Heat
m = Mass
C = Specific Heat
T = Temperature
200
What is the state when IF = KE?
Liquid
200
How much heat is given off by 900 kg of iron when it solidifies at its melting point? (Hf=2.66x105 j/kg)
Q=mHf
Q = (900)(2.66x105)
Q = 2.39 x 108 J
200
Which of the following converts heat energy to mechanical energy?
A. Water flowing over a waterwheel
B. Rubbing your hands together
C. Turning the crank on a generator
D. Boiling water in a steam engine
D. Boiling water in a steam engine
300
If you put a hot metal spoon in a cup of cool water, what happens to the molecules in the water?
They molecules in the water gain energy and speed up.
300
Iron has a higher specific heat than copper does. What does this mean for the time it takes to heat the object up?
Iron takes longer to heat up than copper because it takes more energy to heat up 1 gram than it does copper.
300
Which form of matter has free electrons?
Plasma
300
How much heat is required to vaporize 1.75 kg of liquid water at its boiling point (Hv = 2.26 x 106 J/kg)
Equation: Q=mHv
Q = (1.75)(2.26x106)
Q = 3.95x106 J
300
Considering the equation for the first law of thermodynamics, U=Q-W, if 100J of heat is added to a system that does 600 J of work, what is the internal energy of the system?
Heat is added so 100 will be positive
Work is done by the system so the 600 will be positive.
100 - 600 = -500 J (there is a loss of internal energy)
400
When does heat stop transferring?
When the two objects reach the same temperature (equilibrium).
400
The amount of heat needed to raise 2.0 kg of a substance by 80 K is 33 kJ.
What is the specific heat of the substance? (Hint: Heat needs to be in J)
Q=mCT
C= Q/mT
C= 33,000 J /(2)(80)
C = 206 J/kg.K
400
If KE becomes less than IF what phase change occurred?
Condensation: gas to liquid
400
You have a 2.00 kg block of lead. Lead melts at 327.5°C. (C = 130.0 j/kg.c). You start at room temperature; how much heat must you transfer to reach the melting point?
Q=mCT
Q = (2kg)(130)(327.5 - 25)
Q= 78,650 J
400
According to the first law of thermodynamics, if a system is entirely isolated, which of the following conditions apply?
A. Q>0, W<0
B. Q>0, W=0
C. Q=0, W<0
D. Q=0, W=0
If the system is entirely isolated, there would be no heat transfer or no work being done. So, D would be the correct answer.
500
Which 2 objects have the greatest heat transfer when placed next to each other?
Object A - 200K
Object B - 275 K
Object C - 225 K
Object D - 245 K
Objects A and B, because they have the greatest temperature difference.
500
A 0.20 kg block of a substance requires 1.79 kJ of heat to raise its temperature by 20 K.
What is the substance?
Specific heats:
Aluminim: 897 J/g.k
Gold: 130 J/g.k
Iron: 450 J/g.k
Silver: 235 J/g.k
Q=mCT
C=Q/mT
C= 1,790J/(.20x20)
C = 447.5 J/g.k
Iron
500
Where on the graph would you use the equation for heat of vaporization?
4 because at this point the liquid is turning into a gas
500
It takes 1.5x103 J of heat to melt an amount of gold (Hf=6.30x104 j/kg). How much gold do you have?
Q=mHf
m=Q/Hf
m = (1.5x103)/(6.30x104)
m = 0.024 kg or 24g
500
What is the change of entropy for a heat engine using 500.0 J at 20.0°C?
ΔS=Q/T
= 500/(273+20)
= 1.71 J/K