Name: Absolute Temperature Scale
Uploaded: 2019-07-19
Duration: 10 min 32 s
Description: It’s time to learn about the absolute temperature scale or the Kelvin scale. Watch this video and understand its relation with the third law of thermodynamics.

Question

A student performed an experiment to measure the pressure and the volume of a gas at constant temperature and noted the following:

Pressure $(mm of Hg)$	Volume $({cm}^{3})$
$100$	$80$
$125$	$x$
$200$	$40$
$y$	$32$

Calculate the value of $x$ and $y$ . Which law was used in the calculations? Draw a graph to show volume plotted against pressure.

Accepted Answer

The value of $x$ and $y$ can be calculated by using Boyle's law. It states that volume of a given mass of a dry gas is inversely proportional to its pressure at constant temperature.

According to Boyle's law, $P_{1} V_{1} = P_{2} V_{2}$

Therefore, we can consider $100$

On substituting the values, we get:

$100 \times 80 = 125 \times x$

$x = \frac{100 \times 80}{125}$

$x = \frac{8000}{125} = 64 {cm}^{3}$

$∴$ The volume $x = 64 {cm}^{3}$ .

Similarly, according to Boyle's law, we can consider $P_{3} V_{3} = P_{4} V_{4}$ .

Therefore, $P_{3} = 200 cm of Hg, V_{3} = 40 {cm}^{3}, P_{4} = y, V_{4} = 32 {cm}^{3}$

On substituting the values, we get:

$200 \times 40 = y \times 32$

$y = \frac{200 \times 40}{32}$

$y = \frac{8000}{32} = 250 mm of Hg$

$∴$ The volume $y = 250 mm of Hg$ .

The graph of volume plotted against pressure for the following value is as follows:

Pressure $(mm of Hg)$ Volume $({cm}^{3})$

$100$ $80$

$125$ $64$

$200$ $40$

$250$ $32$

The graph is an isothermic.

Important Questions on Study of Gas Laws

Learn and Prepare for any exam you want !

Pressure $y = \frac{8000}{32} = 250 mm of Hg$	Volume $({cm}^{3})$
$∴$	$80$
$125$	$64$
$200$	$40$
$250$	$32$