Question

400 ml of a gas is contained at 300 mm Hg and 0°C. What will its volume be in mL at 140 mm Hg and 10°C?

Answer 1

The `"combined gas law"` holds that for a given quantity of gas.......

..........`V_2=889*mL`

Explanation:

The `"combined gas law"` holds that for a given quantity of gas.......

`(P_1V_1)/T_1=(P_2V_2)/T_2`, so we convert to absolute temperature, and solve for `V_2`.

`V_2=(P_1V_1T_2)/(T_1P_2)`.

We immediately see (do we?) that the right hand side of the equation has units of volume as required.

And so,

`V_2=(300*mm*Hgxx400*mLxx283*K)/(273*Kxx140*mm*Hg)=889*mL.`

Normally, we would have to convert the pressure measurement to a more conventional atmospheres (i.e. `760*mm*Hg-=1*atm)`, but we can forgo this step here since the pressure measurements cancel.