Question

a.) Write the balanced incomplete combustion reaction for ethane (C2H6), producing CO and water vapour. Make sure to include phases. Also, make sure that the stoichiometric coefficients are whole numbers and are not fractions.
b.) What is the enthalpy of the reaction (ΔH°rxn), in kJ, for the process in part (a)?
c.) Calculate the total heat (q), in kJ, produced by 250.0 g of ethane when 9.00% by mass of it burns incompletely and the remainder burns completely.

Answer 1

Answer on Question #55343 - Chemistry - General chemistry

Question:

a.) Write the balanced incomplete combustion reaction for ethane (C₂H₆), producing CO and water vapour. Make sure to include phases. Also, make sure that the stoichiometric coefficients are whole numbers and are not fractions.

b.) What is the enthalpy of the reaction (ΔH°rxn), in kJ, for the process in part (a)?

c.) Calculate the total heat (q), in kJ, produced by 250.0 g of ethane when 9.00% by mass of it burns incompletely and the remainder burns completely.

Solution

a) 2C₂H₆(g) + 5O₂(g) = 4CO(g) + 6H₂O(g)

b) ΔH°rxn = 4ΔH°(CO) + 6ΔH°(H₂O) - 2ΔH°(C₂H₆) - 5ΔH°(O₂)

ΔH°rxn = 4ΔH°(CO) + 6ΔH°(H₂O) - 2ΔH°(C₂H₆) - 5ΔH°(O₂)

ΔH°rxn = 4 × (-110.5) + 6 × (-241.8) - 2 × (-84) - 5 × (0) = -1724.8 kJ

c) Burns incompletely 250×0.09 = 22.5 g of ethane, it corresponds to the amount of

M(C₂H₆) = 30.1 g/mol, n = 22.5/30.1 = 0.748 mol

2 mol of ethane make 1724.8 kJ of heat

0.748 mol of ethane make x kJ of heat

X = 0.748×1724.8/2 = 645.1 kJ

Burns completely 250-22.5 = 227.5 g of ethane, it corresponds to the amount of

M(C₂H₆) = 30.1 g/mol, n = 227.5/30.1 = 7.56 mol

For total combustion of ethane:

2C₂H₆(g) + 7O₂(g) = 4CO₂(g) + 6H₂O(g)

ΔH°rxn = 4 × (-393.5) + 6 × (-241.8) - 2 × (-32) - 7 × (0) = -2960.8 kJ

2 mol of ethane make 2960.8 kJ of heat

7.56 mol of ethane make x kJ of heat

X = 7.56×2960.8/2 = 11191.8 kJ

Answer: 1724.8 kJ; 645.1 kJ; 11191.8 kJ

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