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Reviewed CSCA Chemistry question · Standard

A rigid container holds 2.0 mol of an ideal gas at a pressure of 1.5 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. 1.0
  2. 2.25
  3. 3.0
  4. 4.5
Show the answer and explanation

Correct answer

B. 2.25

Principle or equation

At constant volume and amount of gas, pressure is directly proportional to absolute temperature (Gay-Lussac's law), derived from the ideal gas law PV = nRT.

Why this answer is correct

Using P1/T1 = P2/T2 with T in kelvin: 1.5 atm / 300 K = P2 / 450 K. Solving gives P2 = 1.5 * 450 / 300 = 2.25 atm.

Example

If a gas at 1.0 atm and 200 K is heated to 400 K at constant volume, the pressure doubles to 2.0 atm.

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