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"`
संबंधित प्रश्न
Specific heat capacity of substance A is 3.8 J g-1K-1 whereas the specific heat capacity of substance B is 0.4 J g-1 K-1
(i) Which of the two is a good conductor of heat?
(ii) How is one led to the above conclusion?
(iii) If substances A and B are liquids then which one would be more useful in car radiators?
Why do the farmers fill their fields with water on a cold winter night?
How will rise in sea level affect population in coastal countries?
In Regnault's apparatus for measuring specific heat capacity of a solid, there is an inlet and an outlet in the steam chamber. The inlet is near the top and the outlet is near the bottom. Why is it better than the opposite choice where the inlet is near the bottom and the outlet is near the top?
Specific heat capacity of a substance A is 3.8 J g-1 K-1 and of substance B is 0.4 J g-1 k-1. Which substance is a good conductor of heat? How did you arrive at your conclusion?
Write an expression for the heat energy liberated by a hot body.
A piece of ice is heated at a constant rate. The variation of temperature with heat input is shown in the graph below:
(i) What are represented by AB and CD?
(ii) What conclusion can you draw regarding the 110°c nature of ice from the above graph?
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?
Observe the following diagram and answer the questions given below:
Specific heat capacity of metals
- Which element has maximum specific heat capacity? Justify.
- Which element has minimum specific heat capacity? Justify.
- Define specific heat of object.
