JAMB 2018 Chemistry · Question 50

To what temperature must a gas at 273k be heated in order to double both its volume and pressure?

Options

  1. A.298K
  2. B.546K
  3. C.819K
  4. D.1092K

Answer: D. 1092K

Explanation written with AI and checked against the answer key

Analysis

This question tests your understanding of the General Gas Law, which combines Boyle’s Law, Charles’s Law, and the Pressure Law. The formula is:

P1V1T1=P2V2T2\frac{P_1V_1}{T_1} = \frac{P_2V_2}{T_2}
Concept

The General Gas Law states that for a fixed mass of gas, the ratio of the product of pressure and volume to the temperature remains constant.

  • P1,V1,T1P_1, V_1, T_1 are the initial pressure, volume, and temperature.
  • P2,V2,T2P_2, V_2, T_2 are the final pressure, volume, and temperature.
Step-by-Step Solution
  1. Identify the given values: • Initial temperature (T1T_1) = 273 K273\text{ K} • Initial pressure = P1P_1 • Initial volume = V1V_1
  1. Identify the final conditions: • The pressure is doubled: P2=2P1P_2 = 2P_1 • The volume is doubled: V2=2V1V_2 = 2V_1 • Final temperature (T2T_2) = ?
  1. Substitute these into the formula: $P1×V1273=(2P1)×(2V1)T2\frac{P_1 \times V_1}{273} = \frac{(2P_1) \times (2V_1)}{T_2}$
  1. Simplify the equation: $P1V1273=4P1V1T2\frac{P_1V_1}{273} = \frac{4P_1V_1}{T_2}$
  1. Cancel out P1P_1 and V1V_1 from both sides: $1273=4T2\frac{1}{273} = \frac{4}{T_2}$
  1. Solve for T2T_2: $T2=273×4T_2 = 273 \times 4$ $T2=1092 KT_2 = 1092\text{ K}$
Conclusion

By doubling both the pressure and the volume, the temperature must increase by a factor of 2×2=42 \times 2 = 4. Multiplying the initial temperature of 273 K273\text{ K} by 44 gives 1092 K1092\text{ K}.

Exam Tip: When dealing with gas law problems, always ensure your temperature is in Kelvin. If a question gives you temperature in Celsius, add 273273 to it before plugging it into your formula. Also, remember that if both PP and VV increase, the temperature must increase significantly to maintain the balance!

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