Question

If 17 L of a gas at a temperature of 67°C and a pressure of 88.89 atm has its temperature increased to 94°C and its volume decreased to 12 L, what is the new pressure?

Answer 1

The new pressure will be `"140 atm"`.

Explanation:

This is an example of the combined gas law. The equation to use is:

`(P_1V_1)/T_1=(P_2V_2)/(T_2)`,

where `P` is the pressure, `V` is the volume, and `T` is the temperature in Kelvins. For this question, the temperature in degrees Celsius will be converted to Kelvins by adding `273.15`.

Write what you know.

`P_1="88.89 atm"`
`V_1="17 L"`
`T_1="67"^@"C" + 273.15="340 K"`
`V_2="12 L"`
`T_2="94"^@"C" + 273.15="367 K"`

Write what you don't know: `P_2`

Solution
Rearrange the equation to isolate `P_2`, substitute the known values into the equation, and solve.

`"P_2=(P_1V_1T_2)/(V_2T_1)`

`P_2=(88.89"atm"xx17"L"xx367"K")/(12"L"xx340"K")="140 atm"` rounded to two significant figures