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Reviewed CSCA Chemistry question · Standard

A rigid container holds 0.80 mol of an ideal gas at a pressure of 2.0 atm and a temperature of 300 K. The gas is heated to 450 K while the volume remains constant. What is the new pressure in atm?

  1. 1.3 atm
  2. 2.0 atm
  3. 3.0 atm
  4. 4.0 atm
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Correct answer

C. 3.0 atm

Principle or equation

For a fixed amount of gas at constant volume, pressure is directly proportional to absolute temperature (Amontons's law): P1/T1 = P2/T2.

Why this answer is correct

P1 = 2.0 atm, T1 = 300 K, T2 = 450 K. P2 = P1 × (T2/T1) = 2.0 atm × (450/300) = 2.0 × 1.5 = 3.0 atm.

Example

If a gas at 1.0 atm and 300 K is heated to 600 K at constant volume, the new pressure is 2.0 atm.

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