Question

If 20 cm3 gas at 1 atm is expanded to 50cm3 at constant t then what is the final pressure

Answer 1

This expansion is done at constant temperature then it must follow Boyles law

then

P1V1=P2V2

20*1=50*x
x=0.4 atm

Answer 2

Answer:

The final pressure is 0.4 atm.

Explanation:

Given: For constant temperature T,

Initial volume, $V_1 =20$ $cm^3$

Initial Pressure, $P_1=1$ atm

Final volume, $V_2=50$ $cm^3$

Recall the Boyle's law,

Also known as volume pressure relationship — states that the pressure P of a gas is inversely to its volume V at a constant temperature, i.e.,

P ∝ 1/V

⇒ P = $\frac{k}{V}$, where $k$ is a constant

⇒ PV = k

So,

$P_1V_1=k$ and $P_2V_2=k$

⇒ $P_1V_1=P_2V_2$ ...... (1)

Substitute the values in (1), we get

1 × 20 = $P_2$ × 50

⇒ $P_2$ = 20/50

⇒ $P_2$ = 2/5

⇒ $P_2$ = 0.4 atm

As volume increases, pressure decreases.

Therefore, the final pressure is 0.4 atm.

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