"2.50 L"2.50 L of a gas at "303 K"303 K and "100 kPa"100 kPa are heated. The new volume is "3.75 L"3.75 L and the new pressure is "90.0 kPa"90.0 kPa. What is the new temperature?

1 Answer
Aug 9, 2017

"409 K"409 K to three significant figures.

Explanation:

This question is an example of the combined gas law. The formula is:

(P_1V_1)/T_1=(P_2V_2)/T_2P1V1T1=P2V2T2

Organize the data:

Known

P_1="100 kPa"P1=100 kPa

V_1="2.50 L"V1=2.50 L

T_1="303 K"T1=303 K

P_2="90.0 kPa"P2=90.0 kPa

V_2="3.75 L"V2=3.75 L

Unknown

T_2T2

Solution

Rearrange the formula to isolate T_2T2. Insert your data and solve.

T_2=(P_2V_2T_1)/(P_1V_1)T2=P2V2T1P1V1

T_2=((90.0color(red)cancel(color(black)("kPa"))xx3.75color(red)cancel(color(black)("L"))xx303"K"))/((100color(red)cancel(color(black)("kPa"))xx2.50color(red)cancel(color(black)("L"))))="409K" rounded to three significant figures

("100 kPa" is an exact number so it has an infinite number of significant figures.)