---
title: "In biological systems, endergonic reactions are often coupled to the exergonic hydrolysis of adenosine triphosphate (\\(\\text{ATP}\\)) to make the overall metabolic process thermodynamically favorable. The thermochemical equations for the enzyme-catalyzed coupled synthesis of glutamine and for the hydrolysis of \\(\\text{ATP}\\) at \\(298\\text{ K}\\) are given below.  \\[\\text{Glutamate}^-\\text{(aq)} + \\text{NH}_4^+\\text{(aq)} + \\text{ATP}^{4-}\\text{(aq)} \\rightarrow \\text{Glutamine(aq)} + \\text{ADP}^{3-}\\text{(aq)} + \\text{HPO}_4^{2-}\\text{(aq)} + \\text{H}^+\\text{(aq)} \\quad \\Delta G^\\circ = -17\\text{ kJ/mol}_{\\text{rxn}}\\]  \\[\\text{ATP}^{4-}\\text{(aq)} + \\text{H}_2\\text{O(l)} \\rightarrow \\text{ADP}^{3-}\\text{(aq)} + \\text{HPO}_4^{2-}\\text{(aq)} + \\text{H}^+\\text{(aq)} \\quad \\Delta G^\\circ = -31\\text{ kJ/mol}_{\\text{rxn}}\\]  Based on this information, what is the standard Gibbs free energy change, \\(\\Delta G^\\circ\\), for the uncoupled synthesis of glutamine represented by the equation below?  \\[\\text{Glutamate}^-\\text{(aq)} + \\text{NH}_4^+\\text{(aq)} \\rightarrow \\text{Glutamine(aq)} + \\text{H}_2\\text{O(l)}\\]"
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date_modified: "2026-08-21T08:17:35+00:00"
---

# In biological systems, endergonic reactions are often coupled to the exergonic hydrolysis of adenosine triphosphate (\(\text{ATP}\)) to make the overall metabolic process thermodynamically favorable. The thermochemical equations for the enzyme-catalyzed coupled synthesis of glutamine and for the hydrolysis of \(\text{ATP}\) at \(298\text{ K}\) are given below.

\[\text{Glutamate}^-\text{(aq)} + \text{NH}_4^+\text{(aq)} + \text{ATP}^{4-}\text{(aq)} \rightarrow \text{Glutamine(aq)} + \text{ADP}^{3-}\text{(aq)} + \text{HPO}_4^{2-}\text{(aq)} + \text{H}^+\text{(aq)} \quad \Delta G^\circ = -17\text{ kJ/mol}_{\text{rxn}}\]

\[\text{ATP}^{4-}\text{(aq)} + \text{H}_2\text{O(l)} \rightarrow \text{ADP}^{3-}\text{(aq)} + \text{HPO}_4^{2-}\text{(aq)} + \text{H}^+\text{(aq)} \quad \Delta G^\circ = -31\text{ kJ/mol}_{\text{rxn}}\]

Based on this information, what is the standard Gibbs free energy change, \(\Delta G^\circ\), for the uncoupled synthesis of glutamine represented by the equation below?

\[\text{Glutamate}^-\text{(aq)} + \text{NH}_4^+\text{(aq)} \rightarrow \text{Glutamine(aq)} + \text{H}_2\text{O(l)}\]

In biological systems, endergonic reactions are often coupled to the exergonic hydrolysis of adenosine triphosphate (\(\text{ATP}\)) to make the overall metabolic process thermodynamically favorable. The thermochemical equations for the enzyme-catalyzed coupled synthesis of glutamine and for the hydrolysis of \(\text{ATP}\) at \(298\text{ K}\) are given below.

\[\text{Glutamate}^-\text{(aq)} + \text{NH}_4^+\text{(aq)} + \text{ATP}^{4-}\text{(aq)} \rightarrow \text{Glutamine(aq)} + \text{ADP}^{3-}\text{(aq)} + \text{HPO}_4^{2-}\text{(aq)} + \text{H}^+\text{(aq)} \quad \Delta G^\circ = -17\text{ kJ/mol}_{\text{rxn}}\]

\[\text{ATP}^{4-}\text{(aq)} + \text{H}_2\text{O(l)} \rightarrow \text{ADP}^{3-}\text{(aq)} + \text{HPO}_4^{2-}\text{(aq)} + \text{H}^+\text{(aq)} \quad \Delta G^\circ = -31\text{ kJ/mol}_{\text{rxn}}\]

Based on this information, what is the standard Gibbs free energy change, \(\Delta G^\circ\), for the uncoupled synthesis of glutamine represented by the equation below?

\[\text{Glutamate}^-\text{(aq)} + \text{NH}_4^+\text{(aq)} \rightarrow \text{Glutamine(aq)} + \text{H}_2\text{O(l)}\]

- **A.** \(-48\text{ kJ/mol}_{\text{rxn}}\)
- **B.** \(-31\text{ kJ/mol}_{\text{rxn}}\)
- **C.** \(-14\text{ kJ/mol}_{\text{rxn}}\)
- **D.** \(+14\text{ kJ/mol}_{\text{rxn}}\)

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/119917/*