Chemistry - Partial pressure (Dalton's Law) exercises

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Step 1 Use the appropriate formula to calculate the pressure of each gas, as if it was on its own, in the 60L vessel.
Step 2 Add up the individual pressures of each gas

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P₁V₁ = P₂V₂_{Continue
with assistance.}

P₁V₁ = P₂V₂

For oxygen
P₁ = 120 kPa, V₁ = 25L, P₂ = ?, V2 = 60L,
P₂ = (120 X 25)/60 = 50 kPa.
For gas nitrogen
P₁ = 200 kPa, V₁ = 25L, P₂ = ?, V2 = 60L,
P₂ = (200 X 25)/600 = 83.3 kPa.

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860 kPa

Since the temperature, pressure and volume of each gas changes but the amount remains fixed, use the formula below.

and tranform to make it equal to P₂

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Calculating the partial pressure of oxygen where
P₁ =230 kPa
V₁ = 40L
T₁ = (20 + 273) = 293K
T₂ = (100 + 273) =373K
V₂ = 100L
P₂ = 230 X 40 X 373/(293 X 100) = 117.12 kPa
Calculating the partial pressure of hydrogen where
P₁ =100 kPa
V₁ = 60L
T₁ = (20 + 273) = 293K
T₂ = (100 + 273) =373K
V₂ = 100L
P₂ = 100 X 60 X 373/(293 X 100) = 76 38 kPa

Hydrogen = 76.38 kPa, oxygen = 117.12 kPa

Partial pressure (Dalton's Law) Exercises
	Two containers are connected by a stopcock as shown on the left. Gas "A" is at a pressure of 202 kPa while gas "B" is at a pressure of 140 kPa. What will the resultant pressure be when the stopcock is opened? Step 1 Calculate the pressure that each gas alone will exert when the stopcock is opened. Since the temperature and amount of each gas is constant we use the formula below. P₁V₁ = P₂V₂ For gas "A" P₁ = 202 kPa, V₁ = 60L, P₂ = ?, V2 = 100L, P₂ = (202 X 60)/100 = 121.2 kPa. For gas "B" P₁ = 140 kPa, V₁ = 40L, P₂ = ?, V2 = 100L, P₂ = (140 X 40)/100 = 56 kPa. Step 2 add the individual pressures of each gas. Total pressure = P_(A) + P_(B) = 121.2 + 56 Total pressure = 177.2 kPa.
Two containers are connected by a stopcock as shown on the right. Gas "A" is at a pressure of 402 kPa while gas "B" is at a pressure of 100 kPa. What will the resultant pressure be when the stopcock is opened?
25 litres of oxygen gas at 120kPa and 25 litres of nitrogen gas at 200 kPa are pumped into an evacuated(empty) 60 litre vessel. What is the final pressure of the 60 litre vessel if the temperature remained constant? Clues
An 60 litre metal vessel contains carbon dioxide at 160 kPa and 23^oC. A further 300 litres of nitrogen gas are pumped into this vessel at 140 kPa and 23^oC. If the volume of the vessel and temperature remain constant what is the final pressure of the vessel? Answer
A vessel containing 60L of hydrogen gas at 20^oC and 100kPa pressure is connected via a valve to a 40L vessel containing oxygen at 20^oC and 230kPa pressure. The valve is opened and both gases expand to fill the entire volume of both vessels. As the valve was opened both vessels were heated to 100^oC. Calculate the partial pressure of each gas. Clues Answer

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