1.3 kg of water, at an initial temperature of 25oC, is heated at a rate of 100 W in a well-insulated container. How much time (i
1 answer:
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A) 1 cal
B) 80 cal
C) 540 cal
Explanation:
A)
The amount of heat energy needed to raise the temperature of a certain mass of a substance is given by
where
m is the mass of the substance
C is the specific heat capacity
is the change in temperature
In this problem:
m = 1 g is the mass of water
is the specific heat capacity of water
is the change in temperature
So, the heat needed is
B)
For a solid substance at its melting point, the amount of heat needed to melt completely the substance is given by
where
m is the mass of the substance
is the specific latent heat of fusion of the substance
In this problem:
- The ice is already at melting point, 0 °C
- Mass of the ice:
- Specific latent heat of fusion of ice:
So, the heat needed is
C)
For a liquid substance at its boiling point, the amount of heat needed to boil completely the substance is given by
where
m is the mass of the substance
is the specific latent heat of vaporization of the substance
In this problem:
- The water is already at boiling point, 100 °C
- Mass of the water:
- Specific latent heat of vaporization of water:
So, the heat needed is