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प्रश्न
Explain how heat capacity of a solid can be determined by the method of mixture.
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उत्तर
- The solid object whose specific heat is to be determined is heated and then put in water in a calorimeter.
- Solid object loses heat energy to water and calorimeter till temperature of all three become equal.
- According to principle of heat exchange,
Heat lost by a solid object (Q) = Heat gained by calorimeter (Q1) + Heat gained by water in the calorimeter (Q2)
This means,
mass of the solid object × its specific heat × in its temperature
= (mass of the calorimeter × its specific heat × increase in its temperature) + (mass of the water × its specific heat × increase in its temperature). - Using this equation, if the specific heat of water and calorimeter are known and other physical quantities are measured accurately, the specific heat of solid object can be determined.
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संबंधित प्रश्न
Given below are observations on molar specific heats at room temperature of some common gases.
| Gas |
Molar specific heat (Cv) (cal mol–1 K–1) |
| Hydrogen | 4.87 |
| Nitrogen | 4.97 |
| Oxygen | 5.02 |
| Nitric oxide | 4.99 |
| Carbon monoxide | 5.01 |
| Chlorine | 6.17 |
The measured molar specific heats of these gases are markedly different from those for monatomic gases. Typically, molar specific heat of a monatomic gas is 2.92 cal/mol K. Explain this difference. What can you infer from the somewhat larger (than the rest) value for chlorine?
What do you understand by the following statements:
The heat capacity of the body is 60JK-1.
Water in lakes and ponds do not freeze at once in cold countries. Give a reason is support of your answer.
An electric heater of power 600 W raises the temperature of 4.0 kg of a liquid from 10.0℃ to 15.0℃ in100 s. Calculate:
- the heat capacity of 4.0 kg of liquid,
- the specific heat capacity of the liquid.
Name two green house gases ?
State three ways to minimize the global warming.
What is meant by specific heat capacity?
Read the following paragraph and answer the questions.
|
If heat is exchanged between a hot and cold object, the temperature of the cold object goes on increasing due to gain of energy and the temperature of the hot object goes on decreasing due to loss of energy. The change in temperature continues till the temperatures of both the objects attain the same value. In this process, the cold object gains heat energy and the hot object loses heat energy. If the system of both the objects is isolated from the environment by keeping it inside a heat resistant box (meaning that the energy exchange takes place between the two objects only), then no energy can flow from inside the box or come into the box. |
- Heat is transferred from where to where?
- Which principle do we learn about from this process?
- How will you state the principle briefly?
- Which property of the substance is measured using this principle?
Study the following procedure and answer the questions below:
1. Take 3 spheres of iron, copper and lead of equal mass.
2. Put all the 3 spheres in boiling water in a beaker for some time.
3. Take 3 spheres out of the water. Put them immediately on a thick slab of wax.
4. Note, the depth that each sphere goes into the wax.
i) Which property of substance can be studied with this procedure?
ii) Describe that property in minimum words.
iii) Explain the rule of heat exchange with this property.
Indian style of cooling drinking water is to keep it in a pitcher having porous walls. Water comes to the outer surface very slowly and evaporates. Most of energy needed for evaporation is taken from the water itself and the water is cooled down. Assume that a pitcher contains 10 kg of water and 0.2 g of water comes out per second. Assuming no backward heat transfer from the atmosphere to the water, calculate the time in which the temperature decrease by 5°C. Specific heat capacity of water = 4200 J kg−1 °C−1 and latent heat of vaporization of water = 2.27 × 106 J kg−1.
Write the approximate values of the specific latent heat of fusion of ice.
Explain, Why is it advisabile to pour cold water over burns, caused on human body, by hot solids?
The temperature of a lead piece of mass 400 g rises from 20°C to 50°C when 1560 J of heat is supplied to it. Calculate: Heat capacity of lead piece.
Numerical Problem.
What could be the final temperature of a mixture of 100 g of water at 90 °C and 600g of water at 20°C.
For a gas `"R"/"C"_"v" = 0.4,` where 'R' is the universal gas constant and 'Cv' is molar specific heat at constant volume. The gas is made up of molecules which are ______.
On supplying 100 µC of charge to a conductor, its potential rises by 5 V then capacity of the conductor is ______.
Water has the lowest specific heat capacity.
Match the following
| 1. | Specific heat capacity | a. | Dewar bottle |
| 2. | Calorimeter | b. | Lavoisier and Simon |
| 3. | Vacuum flask | c. | J Kg-1 K-1 |
| 4. | Ice – calorimeter | d. | Heat capacity |
Thermal capacities of substances A and B are same. If mass of A is more than mass of B then:
Which substance will have more specific heat capacity?
Two blocks P and Q of different metals having their mass in the ratio 2 : 1 are given same amount of heat. Their temperature rises by same amount. Compare their specific heat capacities.
