When 10 g C2H5OH(I) are formed, 51 kJ heat is liberated. Calculate sta

1.	When 10 g C2H5OH(I) are formed, 51 kJ heat is liberated. Calculate standard enthalpy of formation of C2H5OH(I).
Answer» Given : Mass of C₂H₅OH_(I) = m = 10 g Heat liberated = ΔH₁ = -51 kJ Molar mass of C₂H₅OH = 46 gmol^-1 Standard enthalpy of formation of C₂H₅OH_(I) = Δ_fH = ? Standard enthalpy of formation is the enthalpy change for the formation of 1 mole C₂H₅OH_(I) i.e., 46 g C₂H₅OH_(I). Now, ∵ For the formation of 10 g C₂H₅OH_(I) ΔH₁ = -51 kJ ∴ For the formation of 46 g C₂H₅OH, Δ_fH⁰ = \(\frac{-51\times 46}{10}\) = – 234.6 kJ mol^-1 ∴ Standard enthalpy of formation of C₂H₅OH = Δ_fH⁰ = – 234.6 kJ mol^-1

When 10 g C2H5OH(I) are formed, 51 kJ heat is liberated. Calculate standard enthalpy of formation of C2H5OH(I).

Answer»

Given :

Mass of C₂H₅OH_(I) = m = 10 g

Heat liberated = ΔH₁ = -51 kJ

Molar mass of C₂H₅OH = 46 gmol^-1

Standard enthalpy of formation of C₂H₅OH_(I)

= Δ_fH = ?

Standard enthalpy of formation is the enthalpy change for the formation of 1 mole C₂H₅OH_(I)

i.e., 46 g C₂H₅OH_(I).

Now,

∵ For the formation of 10 g C₂H₅OH_(I)

ΔH₁ = -51 kJ

∴ For the formation of 46 g C₂H₅OH,

Δ_fH⁰ = \(\frac{-51\times 46}{10}\) = – 234.6 kJ mol^-1

∴ Standard enthalpy of formation of C₂H₅OH

= Δ_fH⁰ = – 234.6 kJ mol^-1

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