Selina Textbook Solutions: Calorimetry

 Page 1


Class X  Chapter 11 – Calorimetry Physics 
______________________________________________________________________________ 
 
EXERCISE. 11 A 
Question 1:  
Define the term heat. 
Solution 1: 
The kinetic energy due to random motion of the molecules of a substance is known as its heat 
energy. 
 
 
Question 2:  
Name the S.I. unit of heat. 
Solution 2: 
S.I. unit of heat is joule (symbol J). 
 
 
Question 3:  
Define the term calorie. How is it related to joule? 
Solution 3: 
One calorie of heat is the heat energy required to raise the temperature of 1 g of water from 
14.5
o
C to 15.5
 o
C. 
1 calorie = 4.186 J 
 
 
Question 4:  
Define one kilo-calorie of heat. 
Solution 4: 
One kilo-calorie of heat is the heat energy required to raise the temperature of 1 kg of water from 
14.5
o
C to 15.5
o
C. 
 
 
Question 5:  
Define temperature and name its S.I. unit. 
Solution 5: 
The quantity which determines the direction of flow of heat between two bodies kept in contact 
is called temperature. 
S.I. unit kelvin (K). 
 
 
 
 
Page 2


Class X  Chapter 11 – Calorimetry Physics 
______________________________________________________________________________ 
 
EXERCISE. 11 A 
Question 1:  
Define the term heat. 
Solution 1: 
The kinetic energy due to random motion of the molecules of a substance is known as its heat 
energy. 
 
 
Question 2:  
Name the S.I. unit of heat. 
Solution 2: 
S.I. unit of heat is joule (symbol J). 
 
 
Question 3:  
Define the term calorie. How is it related to joule? 
Solution 3: 
One calorie of heat is the heat energy required to raise the temperature of 1 g of water from 
14.5
o
C to 15.5
 o
C. 
1 calorie = 4.186 J 
 
 
Question 4:  
Define one kilo-calorie of heat. 
Solution 4: 
One kilo-calorie of heat is the heat energy required to raise the temperature of 1 kg of water from 
14.5
o
C to 15.5
o
C. 
 
 
Question 5:  
Define temperature and name its S.I. unit. 
Solution 5: 
The quantity which determines the direction of flow of heat between two bodies kept in contact 
is called temperature. 
S.I. unit kelvin (K). 
 
 
 
 
Class X  Chapter 11 – Calorimetry Physics 
______________________________________________________________________________ 
Question 6:  
Differentiate between heat and temperature. 
Solution 6: 
Heat Temperature 
The kinetic energy due to random 
motion of the molecules of a substance 
is known as its heat energy. 
The quantity which determines the 
direction of flow of heat between 
two bodies kept in contact is called 
temperature. 
S.I. unit joule (J). S.I. unit kelvin (K). 
It is measured by the principle of 
calorimetry. It is measured by a thermometer. 
  
 
 
 
Question 7:  
Define calorimetry 
Solution 7: 
The measurement of the quantity of heat is called calorimetry. 
 
 
Question 8:  
Define the term heat capacity and state its S.I. unit. 
Solution 8: 
The heat capacity of a body is the amount of heat energy required to raise its temperature by 1
o
C 
or 1K. 
S.I. unit is joule per kelvin (JK
-1
). 
 
 
Question 9:  
Define the term specific heat capacity and state its S.I. unit. 
Solution 9: 
The specific heat capacity of a substance is the amount of heat energy required to raise the 
temperature of unit mass of that substance through by 1
o
C (or 1K). 
S.I. unit is joule per kilogram per kelvin (Jkg
-1
K
-1
). 
 
 
 
 
Page 3


Class X  Chapter 11 – Calorimetry Physics 
______________________________________________________________________________ 
 
EXERCISE. 11 A 
Question 1:  
Define the term heat. 
Solution 1: 
The kinetic energy due to random motion of the molecules of a substance is known as its heat 
energy. 
 
 
Question 2:  
Name the S.I. unit of heat. 
Solution 2: 
S.I. unit of heat is joule (symbol J). 
 
 
Question 3:  
Define the term calorie. How is it related to joule? 
Solution 3: 
One calorie of heat is the heat energy required to raise the temperature of 1 g of water from 
14.5
o
C to 15.5
 o
C. 
1 calorie = 4.186 J 
 
 
Question 4:  
Define one kilo-calorie of heat. 
Solution 4: 
One kilo-calorie of heat is the heat energy required to raise the temperature of 1 kg of water from 
14.5
o
C to 15.5
o
C. 
 
 
Question 5:  
Define temperature and name its S.I. unit. 
Solution 5: 
The quantity which determines the direction of flow of heat between two bodies kept in contact 
is called temperature. 
S.I. unit kelvin (K). 
 
 
 
 
Class X  Chapter 11 – Calorimetry Physics 
______________________________________________________________________________ 
Question 6:  
Differentiate between heat and temperature. 
Solution 6: 
Heat Temperature 
The kinetic energy due to random 
motion of the molecules of a substance 
is known as its heat energy. 
The quantity which determines the 
direction of flow of heat between 
two bodies kept in contact is called 
temperature. 
S.I. unit joule (J). S.I. unit kelvin (K). 
It is measured by the principle of 
calorimetry. It is measured by a thermometer. 
  
 
 
 
Question 7:  
Define calorimetry 
Solution 7: 
The measurement of the quantity of heat is called calorimetry. 
 
 
Question 8:  
Define the term heat capacity and state its S.I. unit. 
Solution 8: 
The heat capacity of a body is the amount of heat energy required to raise its temperature by 1
o
C 
or 1K. 
S.I. unit is joule per kelvin (JK
-1
). 
 
 
Question 9:  
Define the term specific heat capacity and state its S.I. unit. 
Solution 9: 
The specific heat capacity of a substance is the amount of heat energy required to raise the 
temperature of unit mass of that substance through by 1
o
C (or 1K). 
S.I. unit is joule per kilogram per kelvin (Jkg
-1
K
-1
). 
 
 
 
 
Class X  Chapter 11 – Calorimetry Physics 
______________________________________________________________________________ 
Question 10:  
How is heat capacity of a body related to specific heat capacity of its substance? 
Solution 10: 
Heat capacity = Mass ? specific heat capacity 
 
 
Question 11:  
Differentiate between heat capacity and specific heat capacity. 
Solution 11: 
Heat capacity of the body is the amount of heat required to raise the temperature of (whole) body 
by 1 ? whereas specific heat capacity is the amount of heat required to raise the temperature of 
unit mass of the body by 1 ?. 
Heat capacity of a substance depends upon the material and mass of the body. Specific heat 
capacity of a substance does not depend on the mass of the body. 
S.I. unit of heat capacity is JK
-1
 and S.I. unit of specific heat capacity is Jkg
-1
 K
-1
. 
 
 
Question 12:  
Name a liquid which has the highest specific heat capacity. 
Solution 12: 
Water has the highest specific heat capacity. 
 
 
Question 13:  
Write the approximate value of specific heat capacity of water in S.I. unit. 
Solution 13: 
Specific heat capacity of water = 4200 J kg
-1 
K
-1
. 
 
 
Question 14:  
What do you mean by the following statements: 
(i) the heat capacity of a body is 50JK
-1
 ? 
(ii) The specific heat capacity of copper is 0.4Jg
-1
K
-1
  
Solution 14: 
(i) The heat capacity of a body is 50JK
-1
 means to increase the temperature of this body by 1K 
we have to supply 50 joules of energy. 
 
 
Page 4


Class X  Chapter 11 – Calorimetry Physics 
______________________________________________________________________________ 
 
EXERCISE. 11 A 
Question 1:  
Define the term heat. 
Solution 1: 
The kinetic energy due to random motion of the molecules of a substance is known as its heat 
energy. 
 
 
Question 2:  
Name the S.I. unit of heat. 
Solution 2: 
S.I. unit of heat is joule (symbol J). 
 
 
Question 3:  
Define the term calorie. How is it related to joule? 
Solution 3: 
One calorie of heat is the heat energy required to raise the temperature of 1 g of water from 
14.5
o
C to 15.5
 o
C. 
1 calorie = 4.186 J 
 
 
Question 4:  
Define one kilo-calorie of heat. 
Solution 4: 
One kilo-calorie of heat is the heat energy required to raise the temperature of 1 kg of water from 
14.5
o
C to 15.5
o
C. 
 
 
Question 5:  
Define temperature and name its S.I. unit. 
Solution 5: 
The quantity which determines the direction of flow of heat between two bodies kept in contact 
is called temperature. 
S.I. unit kelvin (K). 
 
 
 
 
Class X  Chapter 11 – Calorimetry Physics 
______________________________________________________________________________ 
Question 6:  
Differentiate between heat and temperature. 
Solution 6: 
Heat Temperature 
The kinetic energy due to random 
motion of the molecules of a substance 
is known as its heat energy. 
The quantity which determines the 
direction of flow of heat between 
two bodies kept in contact is called 
temperature. 
S.I. unit joule (J). S.I. unit kelvin (K). 
It is measured by the principle of 
calorimetry. It is measured by a thermometer. 
  
 
 
 
Question 7:  
Define calorimetry 
Solution 7: 
The measurement of the quantity of heat is called calorimetry. 
 
 
Question 8:  
Define the term heat capacity and state its S.I. unit. 
Solution 8: 
The heat capacity of a body is the amount of heat energy required to raise its temperature by 1
o
C 
or 1K. 
S.I. unit is joule per kelvin (JK
-1
). 
 
 
Question 9:  
Define the term specific heat capacity and state its S.I. unit. 
Solution 9: 
The specific heat capacity of a substance is the amount of heat energy required to raise the 
temperature of unit mass of that substance through by 1
o
C (or 1K). 
S.I. unit is joule per kilogram per kelvin (Jkg
-1
K
-1
). 
 
 
 
 
Class X  Chapter 11 – Calorimetry Physics 
______________________________________________________________________________ 
Question 10:  
How is heat capacity of a body related to specific heat capacity of its substance? 
Solution 10: 
Heat capacity = Mass ? specific heat capacity 
 
 
Question 11:  
Differentiate between heat capacity and specific heat capacity. 
Solution 11: 
Heat capacity of the body is the amount of heat required to raise the temperature of (whole) body 
by 1 ? whereas specific heat capacity is the amount of heat required to raise the temperature of 
unit mass of the body by 1 ?. 
Heat capacity of a substance depends upon the material and mass of the body. Specific heat 
capacity of a substance does not depend on the mass of the body. 
S.I. unit of heat capacity is JK
-1
 and S.I. unit of specific heat capacity is Jkg
-1
 K
-1
. 
 
 
Question 12:  
Name a liquid which has the highest specific heat capacity. 
Solution 12: 
Water has the highest specific heat capacity. 
 
 
Question 13:  
Write the approximate value of specific heat capacity of water in S.I. unit. 
Solution 13: 
Specific heat capacity of water = 4200 J kg
-1 
K
-1
. 
 
 
Question 14:  
What do you mean by the following statements: 
(i) the heat capacity of a body is 50JK
-1
 ? 
(ii) The specific heat capacity of copper is 0.4Jg
-1
K
-1
  
Solution 14: 
(i) The heat capacity of a body is 50JK
-1
 means to increase the temperature of this body by 1K 
we have to supply 50 joules of energy. 
 
 
Class X  Chapter 11 – Calorimetry Physics 
______________________________________________________________________________ 
 
 
(ii) The specific heat capacity of copper is 0.4Jg
-1
K
-1
 means to increase the temperature of one 
gram of copper by 1K we have to supply 0.4 joules of energy. 
 
 
Question 15:  
Name three factors on which heat energy absorbed by a body depends and state how does it 
depend on them.  
Solution 15: 
The quantity of heat energy absorbed by a body depends on three factors : 
(i)Mass of the body - The amount of heat energy required is directly proportional to the mass of 
the substance. 
(ii)Nature of material of the body - The amount of heat energy required depends on the nature 
on the substance and it is expressed in terms of its specific heat capacity c. 
(iii)Rise in temperature of the body - The amount of heat energy required is directly proportional 
to the rise in temperature. 
 
 
Question 16:  
Write the expression for the heat energy Q received by the substance when m kg of substance 
of specific heat capacity c J kg
-1
 k
-1
 is heated through ?t° C. 
Solution 16: 
The expression for the heat energy Q 
Q= mc ? t (in joule) 
 
 
Question 17:  
(a) Same amount of heat is supplied to two liquid A and B. The liquid A and B. The liquid A 
shows a greater rise in temperature. What can you say about the heat capacity of A as compared 
to that of B? 
(b) Two metallic blocks P and Q of masses in ratio 2 : 1 are given same amount of heat. If their 
temperature rise by same amount, compare their specific heat capacities. 
 
Solution 17: 
(a) Heat capacity of liquid A is less than that of B. 
As the substance with low heat capacity shows greater rise in temperature. 
(b) 
Let CP and Cq be the specific heat capacities of blocks P and Q respectively, 
We know that, 
Q
c
mt
?
??
 
Page 5


Class X  Chapter 11 – Calorimetry Physics 
______________________________________________________________________________ 
 
EXERCISE. 11 A 
Question 1:  
Define the term heat. 
Solution 1: 
The kinetic energy due to random motion of the molecules of a substance is known as its heat 
energy. 
 
 
Question 2:  
Name the S.I. unit of heat. 
Solution 2: 
S.I. unit of heat is joule (symbol J). 
 
 
Question 3:  
Define the term calorie. How is it related to joule? 
Solution 3: 
One calorie of heat is the heat energy required to raise the temperature of 1 g of water from 
14.5
o
C to 15.5
 o
C. 
1 calorie = 4.186 J 
 
 
Question 4:  
Define one kilo-calorie of heat. 
Solution 4: 
One kilo-calorie of heat is the heat energy required to raise the temperature of 1 kg of water from 
14.5
o
C to 15.5
o
C. 
 
 
Question 5:  
Define temperature and name its S.I. unit. 
Solution 5: 
The quantity which determines the direction of flow of heat between two bodies kept in contact 
is called temperature. 
S.I. unit kelvin (K). 
 
 
 
 
Class X  Chapter 11 – Calorimetry Physics 
______________________________________________________________________________ 
Question 6:  
Differentiate between heat and temperature. 
Solution 6: 
Heat Temperature 
The kinetic energy due to random 
motion of the molecules of a substance 
is known as its heat energy. 
The quantity which determines the 
direction of flow of heat between 
two bodies kept in contact is called 
temperature. 
S.I. unit joule (J). S.I. unit kelvin (K). 
It is measured by the principle of 
calorimetry. It is measured by a thermometer. 
  
 
 
 
Question 7:  
Define calorimetry 
Solution 7: 
The measurement of the quantity of heat is called calorimetry. 
 
 
Question 8:  
Define the term heat capacity and state its S.I. unit. 
Solution 8: 
The heat capacity of a body is the amount of heat energy required to raise its temperature by 1
o
C 
or 1K. 
S.I. unit is joule per kelvin (JK
-1
). 
 
 
Question 9:  
Define the term specific heat capacity and state its S.I. unit. 
Solution 9: 
The specific heat capacity of a substance is the amount of heat energy required to raise the 
temperature of unit mass of that substance through by 1
o
C (or 1K). 
S.I. unit is joule per kilogram per kelvin (Jkg
-1
K
-1
). 
 
 
 
 
Class X  Chapter 11 – Calorimetry Physics 
______________________________________________________________________________ 
Question 10:  
How is heat capacity of a body related to specific heat capacity of its substance? 
Solution 10: 
Heat capacity = Mass ? specific heat capacity 
 
 
Question 11:  
Differentiate between heat capacity and specific heat capacity. 
Solution 11: 
Heat capacity of the body is the amount of heat required to raise the temperature of (whole) body 
by 1 ? whereas specific heat capacity is the amount of heat required to raise the temperature of 
unit mass of the body by 1 ?. 
Heat capacity of a substance depends upon the material and mass of the body. Specific heat 
capacity of a substance does not depend on the mass of the body. 
S.I. unit of heat capacity is JK
-1
 and S.I. unit of specific heat capacity is Jkg
-1
 K
-1
. 
 
 
Question 12:  
Name a liquid which has the highest specific heat capacity. 
Solution 12: 
Water has the highest specific heat capacity. 
 
 
Question 13:  
Write the approximate value of specific heat capacity of water in S.I. unit. 
Solution 13: 
Specific heat capacity of water = 4200 J kg
-1 
K
-1
. 
 
 
Question 14:  
What do you mean by the following statements: 
(i) the heat capacity of a body is 50JK
-1
 ? 
(ii) The specific heat capacity of copper is 0.4Jg
-1
K
-1
  
Solution 14: 
(i) The heat capacity of a body is 50JK
-1
 means to increase the temperature of this body by 1K 
we have to supply 50 joules of energy. 
 
 
Class X  Chapter 11 – Calorimetry Physics 
______________________________________________________________________________ 
 
 
(ii) The specific heat capacity of copper is 0.4Jg
-1
K
-1
 means to increase the temperature of one 
gram of copper by 1K we have to supply 0.4 joules of energy. 
 
 
Question 15:  
Name three factors on which heat energy absorbed by a body depends and state how does it 
depend on them.  
Solution 15: 
The quantity of heat energy absorbed by a body depends on three factors : 
(i)Mass of the body - The amount of heat energy required is directly proportional to the mass of 
the substance. 
(ii)Nature of material of the body - The amount of heat energy required depends on the nature 
on the substance and it is expressed in terms of its specific heat capacity c. 
(iii)Rise in temperature of the body - The amount of heat energy required is directly proportional 
to the rise in temperature. 
 
 
Question 16:  
Write the expression for the heat energy Q received by the substance when m kg of substance 
of specific heat capacity c J kg
-1
 k
-1
 is heated through ?t° C. 
Solution 16: 
The expression for the heat energy Q 
Q= mc ? t (in joule) 
 
 
Question 17:  
(a) Same amount of heat is supplied to two liquid A and B. The liquid A and B. The liquid A 
shows a greater rise in temperature. What can you say about the heat capacity of A as compared 
to that of B? 
(b) Two metallic blocks P and Q of masses in ratio 2 : 1 are given same amount of heat. If their 
temperature rise by same amount, compare their specific heat capacities. 
 
Solution 17: 
(a) Heat capacity of liquid A is less than that of B. 
As the substance with low heat capacity shows greater rise in temperature. 
(b) 
Let CP and Cq be the specific heat capacities of blocks P and Q respectively, 
We know that, 
Q
c
mt
?
??
 
Class X  Chapter 11 – Calorimetry Physics 
______________________________________________________________________________ 
P
Q
Q
C1
2m t
Q
C2
mT
??
????
??
? ? ?
????
??
????
??
?? ??
 
Hence, the required ratio is 1 : 2  
 
 
Question 18:  
Why do the farmers fill their fields with water on a cold winter night? 
Solution 18: 
In the absence of water, if on a cold winter night the atmospheric temperature falls below 0
o
C, 
the water in the fine capillaries of plant will freeze, so the veins will burst due to the increase in 
the volume of water on freezing. As a result, plants will die and the crop will be destroyed. In 
order to save the crop on such cold nights, farmers fill their fields with water because water has 
high specific heat capacity, so it does not allow the temperature in the surrounding area of plants 
to fall up to 0
o
C. 
 
 
Question 19:  
Discuss the role of high specific heat capacity of water with reference to climate in coastal areas.  
Solution 19: 
The specific heat capacity of water is very high. It is about five times as high as that of sand. 
Hence the heat energy required for the same rise in temperature by a certain mass of water will 
be nearly five times than that required by the same mass of sand. Similarly, a certain mass of 
water will give out nearly five times more heat energy than that given by sand of the same mass 
for the same fall in temperature. As such, sand gets heated or cooled more rapidly as compared 
to water under the similar conditions. Thus a large difference in temperature is developed 
between the land and the sea due to which land and sea breezes are formed. These breezes make 
the climate near the sea shore moderate. 
 
 
Question 20:  
Water is used in hot water bottles for fomentation give a reason. 
Solution 20: 
The reason is that water does not cool quickly due to its large specific heat capacity, so a hot 
water bottle provides heat energy for fomentation for a long time.