Thanks in advance (a) Balance the ideal combustion of ethanol. C_2H_5OH, with ai

Question

Thanks in advance (a) Balance the ideal combustion of ethanol. C_2H_5OH, with air (b) How many pounds of CO_2 are produced for each ton of ethanol that is burned? Given molecular mass of C = 12.0 g mol, H = 1.0 g/mol, and O = 16.0 g/mol. (c) The heat of combustion of ethanol is 13.180 Btu/lbm. Calculate the heat released upon burning one ton of ethanol. (d) How many pounds of CO_2 are produced per million Btu of heat released by burning ethanol? (e) It is known that gasoline produces 150 pounds of CO_2 per million Btu of heat released. Suppose Congress were to pass a law requiring automobiles to burn ethanol instead of gasoline. Would such a law reduce CO_2 emissions from automobiles by at least 5%? Explain.

Explanation / Answer

a) The balanced equation for the combustion of ethanol is

                              C2H5OH + 3O2 ---------> 2CO2 + 3H2O

b) Molecular mass of CO2 = 12.0 + 2(16.0) = 44.0g/mol

Molecular mass of ethanol = 2(12.0) + 6(1.0) + 16.0 = 46.0g/mol

1mole of ethanol produces 2 moles of CO2

Or

46.0 g of ethanol produces (2 x 44.0) = 88.0 g of CO2

1 ton of ethanol = 907.185 Kg of ethanol

So, 907.185 Kg of ethanol produces 907.185 Kg x (88.0/46.0) = 1735.48 Kg of CO2.

Now convert Kg into pound-

0.45359237 kg = 1 pound

1735.48 Kg of CO2 = 1735.48 /0.45359237

= 3826.08 pound CO2

c) 1ton equals to 2000 pounds

Heat of combustion of ethanol is 13,180 Btu /lbm.

Calculate heat released by burning of 1 ton of ethanol

1 lbm of ethanol releases 13,180 Btu heat

2000lbm (1ton) of ethanol releases 13,180 x 2000 Btu heat= 26360000 Btu /ton

d)

When 13,180 Btu heat is released 1 pound of CO2 is produced by burning of ethanol

When 1000000 Btu heat is released 1000000/13,180 pound of CO2 is produced.

When 1000000 Btu heat is released 75.87 pound CO2 is produced.

e) Gasoline produces 150 pound of CO2 per million Btu of heat released, while ethanol produces 75.87 pound CO2 per million Btu of heat released. So if law was passed to use ethanol instead of gasoline it reduces CO2 emissions from automobiles.

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