PHYSICS

JAMB 2021 - Question 27

Physics 2021 JAMB Past Questions - Question 27: The specific latent heat of steam is 2,300J/g and the specific heat capacity of water is 4.2J/gk. When 2g of steam at 100°C condences to water at 40°C, the heat given up is

Choose the correct answers from the options given.
The specific latent heat of steam is 2,300J/g and the specific heat capacity of water is 4.2J/gk. When 2g of steam at 100°C condences to water at 40°C, the heat given up is
A:
B:
C:
D:
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Correct Answer

A

Explanation

To calculate the heat given up when 2g of steam at 100�C condenses to water at 40�C, we can use the following steps:

1. First, we need to calculate the heat released when the steam condenses to water at 100�C.
  Heat released = mass of steam × specific latent heat of steam
  Heat released = 2g × 2300J/g
  Heat released = 4600J

2. Next, we need to calculate the heat released when the water cools from 100�C to 40�C.
  Heat released = mass of water × specific heat capacity of water × temperature change
  Heat released = 2g × 4.2J/g°C × (100°C - 40°C)
  Heat released = 2g × 4.2J/g°C × 60°C
  Heat released = 504J

3. Finally, we add the two amounts of heat released together to find the total heat given up:
  Total heat given up = 4600J + 504J
  Total heat given up = 5104J

Therefore, the heat given up when 2g of steam at 100�C condenses to water at 40�C is 5104J.

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