Powerpoint 5 q's and answers:

1. A gas mixture containing oxygen, nitrogen, and carbon dioxide has a total pressure of 32.9 kPa. If Pressure of oxygen gas = 6.6 kPa, and pressure of nitrogen gas = 23.0 kPa, what is the pressure of carbon dioxide.

Given PO2 = 6.6 kPa
          Ptotal = 32.9 kPa
          PN2= 23.0 kPa

Required: PCO2


Analysis: PCO2 = Ptotal - (PO2 + PN2)
Solve:  PCO2 = 32.9 kPa- ( 6.6 kPa  + 23 kPa+ )
                   = 3.3 kPa

* The pressure of carbon dioxide is 3.3 kPa.

Evaluate: The pressure of the carbon dioxide is suppose to be smaller than the total pressure which means the answer is reasonable.

•2. If I place 3 moles of N2 and 4 moles of O2 in a 35 L container at a temperature of 250 C, what will be the pressure of the resulting mixture of gases be?

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Given : n_nitrogen = 3 moles

             n_oxygen = 4 moles

             V = 35 L

             T = 25˚C or 298 K

Required: P_total

 Analysis: P_nitrogen = nRT/ V

                 P_oxygen = nRT/ V

Solve: : P_{nitrogen =} (3 moles x 8.31 (L*kPa)/ (K*mol) x 298 K) / 35 L

                        = 212 kPa

             P_oxygen = (4 moles x 8.31 (L*kPa)/ (K*mol) x 298 K) / 35 L

                        = 283 kPa

             P_total = 212 kPa + 283 kPa

                      = 495 kPa

           * The resulting pressure of the two gases is 495 kPa.

   Evaluate: Since the partial pressure of oxygen and nitrogen has been added, thus the total pressure should be greater than their partial pressure.