Partial Pressure Question!! HELP!?

A mixture of 2g of CH4 and 1.65g of Si2H6, both gases, are placed in a flask. The total pressure exerted by this mixture is 102kPa. What is the partial pressure?

Any ideas?

Answer:
Molecular weight CH4 = 14 g/mol
moles CH4 = 2 g / 16 = 0.125

Molecular weight Si2H6 = 62.17 g/mol
moles Si2H6 = 1.65 / 62.17 = 0.0265

Total moles = 0.1515

We can use the equation
Pa / Pt = Na / Nt

Pa = Na / Nt x P t = 0.125 x 102 / 0.1515 = 84.1 kPa is the partial pressure of CH4

Partial pressure Si2H6 = 102 - 84.1 = 17.9 kPa

First find the mole of both the substances. The ratio of the moles of the substances indicates the ratio of their respective partial pressure..

Find the molar ratio of the two chemicals. PV=nRT. At fixed V and T, the partial pressure P is dependent only on the number of moles Therefore, the mole ratio is the same as the ratio of partial pressures.

CH4 has a molecular mass of12+4 =16 so 2g=2/16=0.125mole
Si2H6 has a molecular mass of 28*2+6 =62 and 1.65g correspond to 1.65/62 =0.0266mole
the total number of mole are 0.125+ 0.0266=0.1516mole

molar fraction of CH4 is 0.125/0.1516 =0.825 and the partial pressure of CH4 is 0.825*102=84.1kPa

the partial pressure of Si2H2 = total pressure -pressure CH4
=102-84.1= 17.9 kPa

I gave in this form the solution in order that you see all the methods to calculate partial pressures

CH4 =16g/mol Therefore, 2g=2/16=0.125 mole
Si2H6 = 62g/mol Therefore, 1.65g corresponds to 1.65/62 =0.0266 mole.

Total moles = 0.125+ 0.0266=0.1516mole

Mole Fraction of CH4 = 0.125/0.1516 =0.825

The Partial Pressure of CH4 is 0.825 x 102=84.1kPa

The Partial Pressure of Si2H2 = Total pressure -pressure CH4
=102-84.1= 17.9 kPa = 17900 Pa

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Partial Pressure Question!! HELP!?

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