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प्रश्न
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.
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उत्तर
To find final temperature: ∆Q = mc
lOOg of water originally at 90°C will loose an amount of heat,
∆Q = mc ∆T
∆Q = 100 × c × (90 – T)
The same amount of heat will be absorbed by 600g of water originally at 20°C to raise its temperature to T.
∆Q = 600 × c × (T – 30)
600C (T – 20°) = 100C (90° – T)
6T – 120° = 90° – T
6T + T = 120° + 90°
7T = 210° ⇒ T = 210/7
T = 30°C
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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?
Name three fossil fuels that emit carbon dioxide into the atmosphere ?
What is carbon tax?
A piece of iron of mass 2.0 kg has a thermal capacity of 966 J/°C. What is its specific heat capacity in S.I. units?
Read the passage and answer the questions based on it.
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 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 then no energy can flow from inside the box or come into the box. In this situation, we get the following principle.
Heat energy lost by the hot object = Heat energy gained by the cold object. This is called the ‘Principle of heat exchange’.
- Where does heat transfer take place?
- In such a situation which principle of heat do you perceive?
- How can this principle be explained in short?
- Which property of the substance is measured using this principle?
Numerical Problem.
What is the heat in joules required to raise the temperature of 25 grams of water from 0°C to 100°C? What is the heat in Calories? (Specific heat of water = `(4.18"J")/("g"°"C")`
Explain why the specific heat capacity at constant pressure is greater than the specific heat capacity at constant volume.
An office room contains about 4000 moles of air. The change in the internal energy of this much air when it is cooled from 34° C to 19° C at a constant pressure of 1.0 atm is (Use `gamma_"air"` = 1.4 and Universal gas constant = 8.314 J / mol K) ____________.
What is the amount of heat required to raise the temperature of 5 kg of iron from 30°C to 130°C? Specific heat capacity of iron = 483 Jkg-1C-1.
