Question

720 mL of `H_2` gas at 0 degree C and 126.6 kPa is changed to S .T. P. What will be its new volume?

Answer 1

The new volume will be 907 mL.

Explanation:

STP is defined as 0 °C and 1 bar (100 kPa).

Since only the pressure changes, we can use Boyle's Law to solve the problem.

Boyle's Law is

`color(blue)(bar(ul(|color(white)(a/a)P_1V_1 = P_2V_2color(white)(a/a)|)))" "`

We can rearrange Boyle's Law to get

`V_2 = V_1 × P_1/P_2`

In this problem,

`P_1 = "126 kPa"; V_1 = "720 mL"`
`P_2 ="100 kPa"; V_2 = "?"`

∴ `V_2 = "720 mL" × (126 color(red)(cancel(color(black)("kPa"))))/(100 color(red)(cancel(color(black)("kPa")))) = "907 mL"`