Moderate

A gas occupies a volume of 73.5 mL at pressure 710 torr and a temperature of 30°C. What will be its volume in mL at standard pressure and 30°C?

Correct answer: D. 68.7 mL

  • A. 57.5 mL
  • B. 87.6 mL
  • C. 93.5 mL
  • D. 68.7 mL

Explanation

Initial volume V1 = 73.5 mL Initial pressure P1 = 710 torr Final Pressure P2 = 760 torr (standard pressure) Temperature = 30°C Final volume V2 = ? Using the equation of Boyle's law: P1V1 = P2V2 V2 = P1V1/P2 V2 = (710)(73.5)/760 = (71)(73.5)/76 V2 = 68.7 mL ALTERNATIVE METHOD OF SOLVING THE FRACTION: V2 = (710)(73.5)/760 = (71)(73.5)/76 Cancelling 73.5 with 76 since these are close values, we get: V2 = 71 mL The closest value in the options to 71 is 68.7 mL, so it should be the correct option.

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About Ideal Gas Equation

The ideal gas equation, PV = nRT, relates pressure, volume, amount and absolute temperature when gas particles are assumed to have negligible volume and no intermolecular forces. Applications include finding molar mass, density or an unknown gas variable, with careful use of Kelvin temperature and consistent units, and comparison with real-gas behaviour.

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