please solve this problem Process engineering Need full answer n-Hexane (CoH4) i

Question

please solve this problem Process engineering Need full answer n-Hexane (CoH4) is burned with excess air. An analysis of the product gas yields the following dry-basis molar composition: 8.10% CO2, l.98% CO, 0.10% C6H14. The remainder is O2 and N2. The pressure of the product gas is 760 mmHg. Use the Atomic Species Balance method to calculate: a) The percentage conversion of hexane. b) The percentage excess air fed to the burner (do not forget that water is also a product from the combustion). c) The dew point of the product gas, assuming water to be the only condensable species. d) If the temperature of the product gas is brought to 100°C, what will the relative humidity be?

Explanation / Answer

Let the total moles of product gas = 100moles

so moles of CO2 = 8.1 moles

Moles of CO = 1.98 moles

Moles of C6H14 = 0.1 moles

a) We can calcuate hexane going into the system, since all of the carbon in the system comes from the hexane.

Mole of CO and CO2 obtained = 1.98+8.1 = 10.08 moles

Each mole of hexane will give six moles of carbon

so moles of hexane for 10 moles of carbon = 10 /6 = 1.67 moles of hexane

Moles of hexane left = 0.1 moles

So total moles = 1.67 + 0.1 = 1.77 moles o hexane .

so % of hexane reacted = 1.67 X 100 / 1.77 = 94.35 %

b) The combustion equation of hexane is:

C6H14 + 19/2 O2 --> 6CO2 + 7H2O

So for 1 moles we need 9.5 moles of oxygen

so 1.67 moles will require = 9.5 X 1.67 = 15.865 moles of oxygen

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