Q101CP - Chemistry: Molecular Nature Of Matter And Change

Question

Nonspontaneous processes like muscle contraction, protein building, and nerve conduction are coupled to the spontaneous hydrolysis of ATP to ADP. ATP is then regenerated by coupling its synthesis to other energy-yielding reactions such as 

 

$$\begin{gathered} \mathbf{\text{Creatine phosphate}}\mathbf{\to }\mathbf{\text{creatine + phosphate ∆G}}{}^{\mathbf{\text{o}}}\mathbf{\text{'=-43.1kJ/mol}} \\ \mathbf{\text{ADP + phosphate}}\mathbf{\to }\mathbf{\text{ATP ∆G}}{}^{\mathbf{\text{o}}}\mathbf{\text{'=+30.5kJ/mol}} \end{gathered}$$

Calculate  $\mathbf{∆}\mathit{G}{}^{\mathbf{\text{o}}}\mathbf{\text{'}}$ for the overall reaction that regenerates ATP.

Step-by-Step Solution

Answer

The value of $∆G{}^{\text{o}}\text{'}$  for the overall reaction that regenerates ATP is $∆G{}^{\text{o}}\text{'=-12.6kJ/mol}$ .

Step 1: Concept Introduction

A spontaneous process can move in a specific direction without the assistance of an external source of energy. When an external source of energy drives a non-spontaneous process, it moves in a specific direction.

Gibbs free energy, also known as Gibbs function, Gibbs energy, or free enthalpy, is a term used to measure the greatest amount of work done in a thermodynamic system when temperature and pressure remain constant.

Step 2: Calculation for ∆ G ' o

First, combine the two reactions to get the net or overall reaction. The phosphate will just cancel out.

 $\text{Creatine phosphate + ADP}\to \text{creatine + ATP}$

Also combine or add the$∆G{}^{\text{o}}\text{'}$-

$$\begin{gathered} ∆G{}^{\text{o}}\text{'=-43.1kJ/mol+30.5kJ/mol} \\ =-12.6kJ/mol \end{gathered}$$

 Therefore, the value is obtained as$∆G{}^{\text{o}}\text{'-12.6kJ/mol}$.