Ideal Gas Constant R

Overview

The Ideal Gas Constant R is a universal parameter for all gases, representing the amount of energy absorbed when the temperature of one mole of an ideal gas at 273.16 K and one atmospheric pressure is increased by 1 K. Its value is 0.0821 dm3 atm K-1 mol-1 when pressure is in atmospheres and volume in dm3. This constant is crucial in calculations involving ideal gases and is derived based on Avogadro's principle and the units chosen for pressure, volume, and temperature.

Questions and Answers

  1. What is the value of the ideal gas constant R when pressure is in atmospheres and volume in dm3 ?

    The value of R is 0.0821 dm3 atm K-1 mol-1 when pressure is in atmospheres and volume is in dm3.

  2. How is the ideal gas constant R calculated when pressure is in mm Hg and volume is in cm3?

    To calculate R when pressure is in mm Hg and volume is in cm3, the value is 62.4 dm3 mm Hg K-1 mol-1.

  3. What is the value of the ideal gas constant R in SI units?

    In SI units, the value of R is 8.3143 Nm K-1 mol-1 or 8.3143 J K-1 mol-1.

  4. How is the ideal gas constant R related to Avogadro's number of molecules?

    The value of R is a universal parameter for all gases, indicating that Avogadro’s number of molecules of all ideal gases have the same energy demand.

  5. How is the density of an ideal gas calculated using the general gas equation?

    The density of an ideal gas is calculated by substituting the number of moles (n) in terms of mass (m) and molar mass (M) in the equation PV = m/M RT.

Multiple-Choice Questions

  1. What is the value of the ideal gas constant R when the pressure is in atmospheres and volume in dm3?

    a) 0.0821 dm3 atm K-1 mol-1
    b) 8.314 J K-1 mol-1
    c) 62.4 dm3 mm Hg K-1 mol-1
    d) 1.989 cal K-1 mol-1
    Answer: a) 0.0821 dm3 atm K-1 mol-1

  2. Which units are used for pressure, volume, and temperature to calculate the value of R in the general gas equation?

    a) N m-2, m3, K
    b) atm, dm3, °C
    c) mm Hg, cm3, K
    d) Pa, L, °F
    Answer: a) N m-2, m3, K

  3. What is the physical meaning of the value of R in the context of energy absorption by gases?

    a) Gases absorb 1.989 cal of energy when temperature is increased by 1 K.
    b) R represents the energy required to increase the volume of a gas by 1 dm3.
    c) The value of R is a universal parameter for all gases.
    d) R indicates the energy released when pressure is reduced by 1 atm.
    Answer: c) c. The value of R is a universal parameter for all gases.

  4. How is the value of R affected when pressure is expressed in N m-2 and volume in m3 ?

    a) R decreases to 0.0821 dm3 atm K-1 mol-1.
    b) R increases to 8.314 J K-1 mol-1.
    c) R remains the same at 0.0821 dm3 atm K-1 mol-1.
    d) R changes to 62.4 dm3 mm Hg K-1 mol-1.
    Answer: b) R increases to 8.314 J K-1 mol-1.

  5. How does the value of R relate to the molar volume of gases at STP?

    a) R is inversely proportional to the molar volume of gases.
    b) R is directly proportional to the molar volume of gases.
    c) R remains constant regardless of the molar volume of gases.
    d) R determines the density of gases at STP.
    Answer: c. R remains constant regardless of the molar volume of gases.