Question

What will be the pressure of given mass of
gas at constant temparature if volume (v) becomes three
times ?​

Answer 1

Answer:

3 times less pressure.

Explanation:

Using the equation PV = nRT, you can solve this.

R is always a constant, and your question says that temperature (T) and number of moles (n) (which is a representation of mass) stay constant.

First  make the change to the original volume (V) that you specified, so we change the equation to: P3V = nRT

Because everything on the right side is constant, the only thing that can change in order to keep this equation true is volume.

That means that in order to figure out the new volume you isolate it, by dividing both sides by 3V you end up with: P = nRT/3V

If you put the constant values into the equation, you will see that pressure is now 3 times as small as it was before.

If you don't have the values for all the variables, remember that before the change in volume occurred the equation was PV = nRT, or rearranged:

P = nRT/V

That means we went from: P = nRT/V

to P = nRT/3V

As you can see the pressure has decreased by 3 times.

In general, if everything else is constant, the change in pressure will be equal to the inverse of the change in volume, and vice versa, like this:

P = 1/V

or

1/P = V