Q1. A 1 kg block of metal at 100°C is placed in 2 kg of water at 20°C. If the final temperature of the system is 30°C, what is the specific heat capacity of the metal? (Specific heat of water = 4.18 J/g°C) (2020)
Solution:
Using the principle of conservation of energy, calculate the specific heat capacity of the metal.
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Q2. A gas expands isothermally at 300 K from a volume of 1 m³ to 2 m³. If the pressure at the initial state is 100 kPa, what is the work done by the gas?
Q4. If 1000 J of heat is added to a system and 400 J of work is done by the system, what is the change in internal energy of the system? (2021)
Solution:
Using the first law of thermodynamics: ΔU = Q - W = 1000 J - 400 J = 600 J.
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Q5. A 1 kg block of metal at 100°C is placed in 2 kg of water at 20°C. What is the final temperature of the system? (Specific heat of water = 4.18 J/g°C, specific heat of metal = 0.9 J/g°C) (2021)
Solution:
Using conservation of energy: m1*c1*(T_initial - T_final) = m2*c2*(T_final - T_initial). Solving gives T_final = 35°C.
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Q6. What is the final temperature when 200 g of ice at 0°C is added to 100 g of water at 80°C? (Specific heat of water = 4.2 J/g°C) (2020)
Solution:
Using the principle of conservation of energy, the heat lost by water equals the heat gained by ice. Solving gives a final temperature of 20°C.
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Q7. What is the work done on a gas when it is compressed from 4 L to 2 L at a constant pressure of 2 atm?
Solution:
Work done (W) = P * ΔV = 2 atm * (2 L - 4 L) = 2 atm * (-2 L) = -4 L·atm (work done on the gas is positive).
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Q8. A 1000 W heater is used to heat water. How much heat is supplied in 10 minutes? (2020)
Solution:
Heat (Q) = Power (P) * Time (t) = 1000 W * 600 s = 600 kJ.
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Q9. What is the work done when 1 mole of an ideal gas expands isothermally from 10 L to 20 L at a temperature of 300 K? (2020)
