Question

1. The gas inside a balloon has a volume of 15.0 L at a pressure of 2.0 atm Calculate the pressure of the gas if is volume is compressed to 10.0 L at the same temperature

2. A given amount of oxyçen gas has a volume of 25.0 L at a temperature of 37°C and a pressure of 10 atm Atwhat temperature would this gas occupy a volume of 22.0 L at a pressure of 10 atm?

3. The volume of a gas sample at 0 degrees C and 1.0 atm is 10.0 L How many moles of gas are contained in the sample?

4. What would be the pressure of 6.40 g oxygen gas in a vessel with a volume of 4.5 L at 20°C?

5. A sample of oxygen gas, which is saturated with water vapor, is kept in a 10-L vessel at 30°C and has a pressure of 758 Torr If the pressure of the water vapor at this temperature s 31.8 Torr, what would be the pressure of the

dry oxygen?

Answer 1

1) P₁ V₁₌ P₂V₂

2×15= P₂×10

P₂₌ $\frac{2×15}{10}=3atm$

2) T₁₌ 37+273.15=310.15

Pressure is constant

$\frac{V_1}{T_1}= \frac{V_2}{T_2}$

$\frac{25}{310.15}=\frac{22}{T_2}$

$T_2 =\frac{22×310.15}{25}= 272.9K$

3) At $0°C$ and 1 atm, 1 mole of any gas occupies 22.4 litres

Number of moles of 10litre at stp

=$\frac{10}{22.4}= 0.4464 \> moles$

4)Number of moles of oxygen

$= \frac{6.40}{32}=0.2$

$Gas\> constant \>R=0 .082057l.atm/K.Mol$

T=20+273.15= 293.15K

PV=nRT

P=$\frac{0.2×0.082057×293.15}{4.5}$

$=1.069\>atm$

5) Pressure due to Oxygen = Total pressure - vapour pressure

Pressure of dry Oxygen $758-31.8=726.2 torr$