In winemaking, the sugars in grapes undergo fermentationby yeast to yield CH3CH2OH and CO2. During cellularrespiration, sugar and enthanol are "burned" to water vapor andCO2.
A) Using C6H12O6 for sugar, calculate ÄH of fermentation and of respiration(combustion).
B) Write a combustion reaction for ethanol. Which has ahigher ÄH for combustion per mole of C, sugaror ethanol?
am I right?
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ethanol
I need help with B)balancing the equation. Thanks.
Answer this Question•Chemistry - Mark, Saturday, October 24, 2015 at 10:11am
i think it's
C2H6OH(l) + 3O2(g) ---> 2CO2(g) + 3H2O(g)....
Is it right?
Yes, you are correct. The balanced equation for the combustion of ethanol is:
C2H6OH(l) + 3O2(g) ---> 2CO2(g) + 3H2O(g)
This equation represents the combustion of one mole of ethanol (C2H6OH) with three moles of oxygen gas (O2) to produce two moles of carbon dioxide (CO2) and three moles of water (H2O).
Yes, you are correct. The balanced combustion equation for ethanol is:
C2H6OH(l) + 3O2(g) ---> 2CO2(g) + 3H2O(g)
This means that for every 1 mole of ethanol, 2 moles of carbon dioxide and 3 moles of water are produced.
To answer part B of the question, we need to compare the enthalpy change of combustion per mole of carbon for sugar and ethanol. The enthalpy change of combustion (ΔH) can be calculated by subtracting the enthalpy of the reactants from the enthalpy of the products.
For sugar (C6H12O6):
ΔH = [(6 mol CO2 × ΔHf(CO2)) + (6 mol H2O × ΔHf(H2O))] - [(1 mol C6H12O6 × ΔHf(C6H12O6)) + (6 mol O2 × ΔHf(O2))]
For ethanol (C2H6OH):
ΔH = [(2 mol CO2 × ΔHf(CO2)) + (3 mol H2O × ΔHf(H2O))] - [(1 mol C2H6OH × ΔHf(C2H6OH)) + (3 mol O2 × ΔHf(O2))]
By comparing the absolute values of the enthalpy change for each substance, you can determine which one has a higher ΔH for combustion per mole of carbon.
Note: ΔHf represents the standard enthalpy of formation of a particular substance.