CAIE A-Level Physics A2 15.3.1 The Basic Assumptions of the Kinetic Theory of Gases

(a)

The kinetic theory of gases is based on a number of assumptions about the molecules of a gas.

State the assumption that is related to the volume of the molecules of the gas.

[ 2 ]

(b)

An ideal gas occupies a volume of $2.40 \times 10^{-2} \mathrm{~m}^{3}$ at a pressure of $4.60 \times 10^{5} \mathrm{~Pa}$ and a temperature of $23^{\circ} \mathrm{C}$ .

[ 3 ]

(i)

Each molecule has a diameter of approximately $3 \times 10^{-10} \mathrm{~m}$ .

Estimate the total volume of the gas molecules.

volume =m³

[ 3 ]

volume of one atom $=d^{3}\left(=2.7 \times 10^{-29} \mathrm{~m}^{3}\right)$
volume of all atoms $=2.7 \times 10^{-29} \times 2.7 \times 10^{24}$ $=7 \times 10^{-5} \mathrm{~m}^{3}$
or

volume of one atom $=(4 / 3) \pi r^{3}\left(=1.41 \times 10^{-29} \mathrm{~m}^{3}\right)$
volume of all atoms $=2.7 \times 10^{24} \times 1.41 \times 10^{-29}$ $=4 \times 10^{-5} \mathrm{~m}^{3}$

(c)

By reference to your answer in (b)(ii), suggest why the assumption in (a) is justified.

[ 1 ]

numerical comparison between answer to (b)(ii) and $2.4 \times 10^{-2}\left(\mathrm{~m}^{3}\right)$ showing (b)(ii) is much less than $2.4 \times 10^{-2}\left(\mathrm{~m}^{3}\right)$

CAIE A-Level Physics A2 15.3.1 The Basic Assumptions of the Kinetic Theory of Gases Topic Practice

Question 1

Question (a)

Question (b)

Question (i)

Question (c)