Glycine, C₂H₅O₂N, is important for biological energy. The combustion reaction of glycine is given by the equation 4C₂H₅O₂N(s) + 9O₂(g) $\rarr$ 8CO₂(g) + 10H₂O(l) + 2N₂(g) $\Delta$ H^$\circ$_rxn = -3857 kJ/mol
Given that $\Delta$ H^$\circ$_f[CO₂(g) ] = -393.5 kJ/mol and $\Delta$ H^$\circ$_f[H₂O(l) ] = -285.8 kJ/mol, calculate the enthalpy of formation of glycine.

Question

Glycine, C₂H₅O₂N, is important for biological energy. The combustion reaction of glycine is given by the equation 4C₂H₅O₂N(s) + 9O₂(g)

\rarr

8CO₂(g) + 10H₂O(l) + 2N₂(g)

\Delta

H^$\circ$_rxn = -3857 kJ/mol
Given that

\Delta

H^$\circ$_f[CO₂(g) ] = -393.5 kJ/mol and

\Delta

H^$\circ$_f[H₂O(l) ] = -285.8 kJ/mol, calculate the enthalpy of formation of glycine.

Quizplus · Accepted Answer

Using Hess's Law, we can calculate the enthalpy of formation of glycine by subtracting the sum of the enthalpies of formation of the reactants from the sum of the enthalpies of formation of the products, all multiplied by their respective stoichiometric coefficients.

Enthalpy of formation of glycine = [(8)(-393.5 kJ/mol) + (10)(-285.8 kJ/mol) + (2)(0 kJ/mol)] - [(4)(-3857 kJ/mol)]/4
= (-3148 kJ/mol) - (-964 kJ/mol)
= -537.2 kJ/mol

Therefore, the correct answer is C.

Glycine, C2H5O2N, Is Important for Biological Energy →\rarr→ 8CO2(g) + 10H2O(l) + 2N2(g)

Glycine, C₂H₅O₂N, Is Important for Biological Energy $\rarr$ 8CO₂(g) + 10H₂O(l) + 2N₂(g)