Advertisements
Advertisements
प्रश्न
Heat energy is supplied at a constant rate to 100g of ice at 0 °C. The ice is converted into water at 0° C in 2 minutes. How much time will be required to raise the temperature of water from 0 °C to 20 °C? [Given: sp. heat capacity of water = 4.2 J g-1 °C-1, sp. latent heat of ice = 336 J g-1].
Advertisements
उत्तर
Heat energy required to melt 100 g of ice at 0 °C is
Q = mL = 100 × 336=33600 J
Therefore, heat energy supplied per minute is
`33600/2=16800 "J min"^-1`
Now, heat energy required to raise the temperature of water from 0°C to 20°C is
Q'=mc × rise in temperature =100 × 4.2 × 20 = 8400 J
If time required for this heat gain is t minutes, then Heat energy supplied in t minutes is
`16800 xx "t"=8400`
`therefore "t" =8400/16800`
`"t" = 0.5 "min"`
`"t" = 30 "s"`
APPEARS IN
संबंधित प्रश्न
Explain the term boiling ?
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.
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.
How much heat energy is required to change 2 kg of ice at 0°C into water at 20°C? (Specific latent heat of fusion of water = 3,34,000 J/kg, Specific heat capacity of water = 4200 JKg–1K–1).
For a gas, `"R"/"C"_"v"=0.4`, where R Is universal gas constant and Cv is the molar specific heat at constant volume. The gas is made up of molecules, which are ______
A monoatomic gas of pressure 'P' having volume 'V' expands isothermally to a volume '2V' and then adiabatically to a volume '16V'. The final pressure of the gas is ______.
(ratio of specific heats = `5/3`)
Two metals A and B have specific heat capacities in the ratio 2:3. If they are supplied same amount of heat then
If the mass ratio of metal A and metal B is 3:5 then calculate the ratio in which their temperatures rise.
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 |
Calculate the amount of heat energy required to raise the temperature of 200 g of copper from 20°C to 70°C. Specific heat capacity of copper = 390 J kg-1 K-1.
