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Worksheet: Heat and Heat Calculations with Key, Exercises of Chemistry

Chemistry is the study of matter. Heat is basically a temperature rises, solved questions on difference between temperature and heat.

Typology: Exercises

2020/2021

Uploaded on 04/20/2021

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Worksheet: Heat and Heat Calculations Name___________________
KEY
1. What is the difference in temperature and heat?
2. ___
___________
__ is energy in motion. __
______________
__ is stored
energy and _
_______
_ be measured. _
_____________
_ can be measured.
3. When you heat a substance and the temperature rises, how much it rises
depends upon its ___
_________________
___.
4. The definition of specific heat capacity is the amount of _____________
required to do what?
5. You can touch the aluminum pan of a TV dinner soon after is has been taken
from the oven, but you will burn your hand if you touch the food it contains.
Explain.
6. Why doesn’t the temperature of water (for example) continually increase as it
is heated?
7. What equations must be used to calculate the heat associated with a phase
change?
Why can’t the specific heat equation be used?
Temperature is a m easure of the average kinetic energy and does not depend upon the amount of matter in the
sample. Heat is the total kinetic energ y that flows because of a difference in temperature and do es depend on
the amount of mat ter.
Kinetic Energy
cannot
specific heat capac ity
Changes in energy
heat
Potential Energy
Raise 1 gram of a substance 1OC.
The aluminum has a lower specific heat than the food (specifically the water in the food) and it
therefore heats up and cools off more quickly. A lot of hea t must be released before the water
will change its temperature even one degree.
The temperature will NOT increase during phase change s. During a phase change, the heat is
making the solid turn to liquid or the liquid turn to steam rather than increas ing the temperature.
Q = m x
Δ
Hvap or Q = m x
Δ
Hfus
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Worksheet: Heat and Heat Calculations Name___________________ KEY

1. What is the difference in temperature and heat?

2. ___ ___________ __ is energy in motion. __ ______________ __ is stored

energy and _ _______ _ be measured. _ _____________ _ can be measured.

3. When you heat a substance and the temperature rises, how much it rises

depends upon its ___ _________________ ___.

4. The definition of specific heat capacity is the amount of _____________

required to do what?

5. You can touch the aluminum pan of a TV dinner soon after is has been taken

from the oven, but you will burn your hand if you touch the food it contains.

Explain.

6. Why doesn’t the temperature of water (for example) continually increase as it

is heated?

7. What equations must be used to calculate the heat associated with a phase

change?

Why can’t the specific heat equation be used?

Temperature is a measure of the average kinetic energy and does not depend upon the amount of matter in the sample. Heat is the total kinetic energy that flows because of a difference in temperature and does depend on the amount of matter.

Kinetic Energy

cannot

specific heat capacity

Changes in energy

heat

Potential Energy

Raise 1 gram of a substance 1OC.

The aluminum has a lower specific heat than the food (specifically the water in the food) and it therefore heats up and cools off more quickly. A lot of heat must be released before the water will change its temperature even one degree.

The temperature will NOT increase during phase changes. During a phase change, the heat is making the solid turn to liquid or the liquid turn to steam rather than increasing the temperature.

Q = m x Δ Hvap or Q = m x Δ Hfus

Because there is no change in temperature.

Use these charts as needed in the following calculations: You will need your own

paper to complete your calculations.

8. How much heat is required to warm 275 g of water from 76

o

C to 87

o

C?

9. PCl 3 is a compound used to manufacture pesticides. A reaction requires that

96.7 g of PCl 3 be raised from 31.

o

C to 69.

o

C. How much energy will this

require given that the specific heat of PCl 3 is 0.874 J/g

o

C?

10. A quantity of water is heated from 25.

o

C to 36.

o

C by absorbing 325 J of

heat energy. What is the mass of the water?

325 J = ( m ) (4.184 J g o^ C

)(11.4 ° C)

m =

325 J

(4.184 J

g

o C

)(11.4 ° C)

= 6.81g

11. A 500. g sample of an unknown metal releases 6.4 x 10

2

J as it cools from 55.

o

C to 25.

o

C. What is the specific heat of the sample?

-6.4x10 2 J = (500 g)(C)(-30.0 ° C)

C =

-6.4x

2 J

(500 g)(-30.0 ° C)

= 0.0427 J

g o^ C

Substance Specific Heat (J/g

o

C)

H 2 O (l) 4.

H 2 O (steam) 2.

Al (s) 0.

Fe (s) 0.

Water

ΔHfus = 334 J/g

ΔHvap= 2260 J/g

Q = m x C x Δ t Δ t = 87ºC - 76ºC = 11ºC Q = 275 g x 4.184 J/goC x 11°C = 13000 J

Q = m x C x Δ t Δ t = 69.2ºC - 31.7ºC = 37.5ºC Q = 96.7 g x 0.874 J/goC x 37.5ºC = 3170 J

Q = m x C x Δ t Δ t = 36.4ºC – 25.0ºC = 11.4ºC

Q = m x C x Δ t Δ t = 25.0°C - 55.0°C = - 30.0°