# Question 748ea

Mar 28, 2016

The pressure in the chamber is (c) 258 torr.

#### Explanation:

According to Dalton's Law of Partial Pressures, each gas will exert its own partial pressure in the chamber.

Since the temperature is constant, we can use Boyle's Law to calculate the partial pressure of each gas in the chamber.

The formula for Boyle's Law is

color(blue)(|bar(ul(P_1V_1 = P_2V_2)|)

Step 1. Calculate the partial pressure of neon in the chamber.

Boyle's Law can be rearranged to

P_2 = P_1 × V_1/V_2#

${P}_{1} = \text{1005 torr"; V_1 = "0.625 L}$
${P}_{2} = \textcolor{w h i t e}{m m} \text{?"; color(white)(mm)V_2 = "4.25 L}$

${P}_{2} = 1005 \text{torr" × (0.625 color(red)(cancel(color(black)("L"))))/(4.25 color(red)(cancel(color(black)("L")))) = "147.8 torr}$

Step 2. Calculate the partial pressure of helium in the chamber.

${P}_{1} = \text{1324 torr"; V_1 = "0.355 L}$
${P}_{2} = \textcolor{w h i t e}{m m} \text{?"; color(white)(mm)V_2 = "4.25 L}$

${P}_{2} = 1324 \textcolor{w h i t e}{l} \text{torr" × (0.355 color(red)(cancel(color(black)("L"))))/(4.25 color(red)(cancel(color(black)("L")))) = "110.6 torr}$

3. Calculate the total pressure in the chamber.

${P}_{\text{tot" = P_"Ne" + P_"He" = "147.8 torr + 110.6 torr" = "258 torr}}$

The pressure in the chamber is 248 torr.