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5 kg of water at 60°C is given heat of 420 Kilo-Joule. What will be the final temperature of water if specific heat of water is 4,200 Joules per kilogram per degree Celsius?

5 kg of water at 60°C is given heat of 420 Kilo-Joule. What will be the final temperature of water if specific heat of water is 4,200 Joules per kilogram per degree Celsius? Correct Answer 80°C

CONCEPT:

  • Heat is a form of energy that flows from a relatively warmer object to a relatively cooler object.
  • Specific Heat: The amount of heat required to increase the temperature of a unit mass by one unit °C is called the specific heat of the material.

The heat required or lost to change the temperature of mass:

Q = msΔT

where Q is the heat required, m is the mass of the object, and s is the specific heat of the material, and ΔT is the change in temperature.

CALCULATION:

Given that m = 5 kg, Initail temp T1 = 60°C, Q = 420 kJ, s = 4200 J/kg/°C

According to the principle of calorimetry

Heat lost = Heat gained

Let final temperature is T

Q = msΔT

420 kJ = 5 × 4200 × (T - 60)

420 × 103 = 5 × 4200 × (T - 60)

100 = 5 × (T - 60)

20 = (T - 60)

T = 80°C

So the correct answer is option 4.

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