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# Each component contributes to the pressure in the above example. What is the partial pressure... help?

PV = nRT P = nRT/V V = nRT/P n = PV/RT T = PV/nR R = PV/nT

P = Pressure in atmospheres V = Volume in Liters n = number of moles

T = absolute temperature in oK R = the ideal gas constant 0.0821 L-atm/mol-oK

Boyle’s Law: P1V1 = P2V2 Charles’ Law: V1/T1 = V2/T2 P1/T1 = P2/T2

Molar Mass, M: M =mRT/PV For component i, Mole fraction (Xi) = ni/ntotal

where m is the mass of gas Partial pressure of i: Pi = Ptotal x Xi

1 atmosphere = 760 Torr = 760 mm Hg oK = oC + 273.15

Standard Temperature and Pressure (STP) is 0 oC and 1 atm.

6.Each component contributes to the pressure in the above example. What is the partial pressure (in atmospheres) of each of the components above?

Update:

the above example was

What is the volume at STP occupied by a gas mixture having 0.5 mol methane, 0.25 mol hydrogen and 1.25 mol of oxygen?

the answer is: 2.00 mol x 22.4 L/mol=44.8 L

### 2 Answers

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It is just one of those useful facts to remember that 1 mol of any gas (or mixture of gases) occupies 22.4 L at STP. You can derive that from PV = nRT.

As far as the partial pressures are concerned, they are proportional to the number of mols. The total number of mols exerts the total pressure and the individual partial pressures are related to the numbers of mols as a fraction of the total number of mols. The sum of the partial pressures is equal to the total pressure.

• In order to answer this question, we need to know what each component is/was in the above example. You didn't provide us with the above example.

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