Question

"In the absence of an adequate supply of oxygen, yeasts obtains metabolic energy by fermentation of glucose to produce ethanol. C6H12O6(s) LaTeX: \longrightarrow⟶ 2 C2H5OH(l) + 2 CO2(g) Use the standard enthalpies of formation to calculate ΔH for this reaction" Substance ΔHo glucose(s) -304.5 kcal/mol CO2(g) -93.9 kcal/mol C2H5OH(l) -66.4 kcal/mol

Answer 1

Answer: $\Delta H=-16.5 kcal$

Explanation:

The balanced chemical reaction is,

$C_6H_{12}O_6(s)\longrightarrow 2C_2H_5OH(l)+2CO_2(g)$

The expression for enthalpy change is,

$\Delta H=\sum [n\times \Delta H_f(product)]-\sum [n\times \Delta H_f(reactant)]$

$\Delta H=[(n_{C_2H_5OH}\times \Delta H_{C_2H_5OH})+(n_{CO_2}\times \Delta H_{CO_2})]-[(n_{C_6H_{12}O_6}\times \Delta H_{C_6H_{12}O_6})]$

where,

n = number of moles

Now put all the given values in this expression, we get

$\Delta H=[(2\times -66.4)+(2\times -93.9)]-[(1\times -304.5)]$

$\Delta H=-16.5kcal$

Therefore, the enthalpy change for this reaction is -16.5 kcal