Asample of a smokestack emission was collected into a 1.25-l tank at 752 mm hg and analyzed. the analysis showed 92% co2, 3.6% no, 1.2% so2, and 4.1% h2o by mass. what is the partial pressure exerted by each gas?

Answer :

Partial pressure of = 639.952 mmHg

Partial pressure of = 36.757 mmHg

Partial pressure of = 5.757 mmHg

Partial pressure of = 69.533 mmHg

Solution : Given,

Total pressure, = 752 mmHg

From the periodic table, the molar masses of  , NO, and are 44, 30, 64, 18 respectively.

92% by mass means 92g   is present in 100g of smoke.

3.6% NO by mass means 3.6g NO is present in 100g of smoke.

1.2% by mass means 1.2g is present in 100g of smoke.

4.1% by mass means 4.1g is present in 100g of smoke.

step 1 : First calculate the number of moles of each gas.

Formula used :  

Number of moles =     ........(1)

Moles of , = = 2.09 moles

Moles of NO, = = 0.12 moles

Moles of , = = 0.018 moles

Moles of , =   = 0.227 moles

Total number of moles, is calculated as

= + + + = 2.09 + 0.12 + 0.018 + 0.227 = 2.455 moles

step 2 : Now calculate the partial pressure of each gas.

Formula used :

     .........(2)

where,

= partial pressure of x

= moles of x

= total moles

= total pressure

Now put all the values in above formula (2), we get

= = 639.952 mmHg

= = 36.757 mmHg

=   = 5.5136 mmHg

=   = 69.533 mmHg