## Hydrolysis of Acetyl phosphate

$\Delta G^{\circ}= \Delta H^{\circ} - T \Delta S^{\circ}$

$\Delta G^{\circ}= -RT\ln K$

$\Delta G^{\circ}= \sum \Delta G_{f}^{\circ}(products) - \sum \Delta G_{f}^{\circ}(reactants)$

Jacob Afable 3J
Posts: 41
Joined: Fri Sep 25, 2015 3:00 am

### Hydrolysis of Acetyl phosphate

Winter 2013 Q2B:

Why do we divide the hydrolysis of ATP by the formation of acetyl phosphate to get the amount of moles of ATP?

Irena Roy 4H
Posts: 40
Joined: Fri Sep 25, 2015 3:00 am

### Re: Hydrolysis of Acetyl phosphate

The question is essentially asking: How many moles of ATP do you need to hydrolyze in order to get the amount of energy needed to phosphorylate 1 mole of acetyl phosphate?

In this case, the hydrolysis of 1 mole of ATP releases -30.5 kJ in energy.
The hydrolysis of acetyl phosphate is -41 kJ/mol. The phosphorylation of acetic acid is the reverse of this process, for a value of 41 kJ/mol.
1 mole of acetyl phosphate molecules are formed during the phosphorylation of acetic acid. So (41 kJ/mol)(1mol) = 41 kJ.
41 kJ is the amount of energy involved when 1 mole of acetyl phosphate molecules are formed.

So the question is, how many moles of ATP do I need to hydrolyze in order to get 41 kJ?

We know that 1 mole of ATP releases -30.5 kJ aka -30.5 kJ/mol ATP. At this point this is just basic stoichiometry, so: 41 kJ = (30.5 kJ/mol)(x)
Solve for x to get the number of moles of ATP you need to hydrolyze. This should be 1.3 moles of ATP. For part b of this question, use a similar process.