I have balanced both equations. How do i solve them? Any help please 10. A react

Question

I have balanced both equations. How do i solve them? Any help please

10. A reaction vessel with a volume of 100.0L is filled with oxygen at STP. Then, 30.005g of ethanol CzH6O) and 24.500g of butane (CHo) are added and react to form carbon dioxide and water (all reactants and products are in gaseous states). Write and balance the reactions, then calculate the total pressure of the final mixture, assuming constant temperature and volume. Butane reacts much faster than ethanol, so you can assume the reactions happen sequentially

Explanation / Answer

At STP conditions, 1 mole of any gas occupies 22.4 lit of volume

Number of moles of Oxygen in the 100.0 lit vessel at STP = 100/22.4 = 4.464

Number of moles of ethanol = weight/MW =30.005/46 = 0.652

Number of moles of butane = weight/MW = 24.5/58 =0.422

The balanced chemical equation

C4H10 + 13/2 O2 ---------> 4 CO2 + 5 H2O -----------1

C2H6O + 3 O2 ---------> 2 CO2 + 3 H2O    ---------------2

C2H6O + C4H10 + 19/2 O2 ---------> 6 CO2 + 8 H2O

1 mole of C4H10 need 13/2 moles of O2

0.422 mole of C4H10 need ----? moles of O2   =( 0.422/1)x 13/2 = 2.743

Number of moles of O2 left after the reaction wiith C4H10 = 4.464-2.743 =1.721

1 mole of C2H6O need 3 moles of O2

0.652 mole of C2H6O need ----? moles of O2   =( 0.652/1)x 3 = 1.956

After the reaction with butane, the left over oxygen is insuffecient to oxidize ethanol. Here, the limiting regent is Oxygen

3 moles of O2 can oxidixe 1 mole of C2H6O

1.721 moles of O2 can oxidize ------?mole of C2H6O = 1.721/3 = 0.573

So, ethanol is the only reactant left over in the vessel

So, number of moles of ethanol left over in the vessel = 0.652-0.573 = 0.079

From equation-1 number of moles of CO2 and H2O formed (butanol completely oxidized)

CO2 = 0.422 x 4 = 1.688 H2O = 0.422 x 5 = 2.11

From equation-2 number of moles of CO2 and H2O formed (0.573 moles of ethanol oxidized)

CO2 = 0.573 x 2 = 1.146 H2O = 0.573 x 3 = 1.719

Thel number of moles of CO2 , H2O and ethanol left over after the reaction

CO2 = 1.688+1.146=2.834     H2O = 1.719+2.11= 3.829 ethanol = 0.079

Total number of moles = 6.742

At STP conditions

Final pressure P= nRT/V = 6.742x0.0821 x 273/100 = 1.511 atm

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