# Change in GIbbs free energy for ethanol

• koomanchoo
In summary, the conversation is about a question regarding the change in Gibbs energy of ethanol when the pressure is increased isothermally. The individual is having trouble with the calculation and is seeking help. The equation dG=V(Pf-Pi) is mentioned and the need to convert all units into SI-mKgs is emphasized. The conversation ends with the individual thanking Daniel for his help and expressing their appreciation for the forum.
koomanchoo
hey i seem to be having a lot of trouble with this type of question:
Calculate the change in Gibbs energy of 35g of ethanol (mass density = 0.789g cm-3) when the pressure is increased isothermally from 1 atm to 3000 atm.

in my notes i have that dG=V(Pf-Pi) and search up on the net that mass=volume*density so volume of ethanol comes to 35/.789 the answer is suppose to be 10.4kJ but i get nowhere near it.

dG=(35/.789)*(3000-1) is this the right equation because that's all i can find
pls help me! thanks
P.K

Okay.Maybe

$$\Delta G=V\Delta p$$

sounds right.I'm sure you need to convert all units into SI-mKgs.

1 atm=101,325 Pa
1 cm^{3}=10^{-6}m^{3}

1kJ=1000J

Daniel.

thanks man

Thanks heeeeeeeeeaps! Daniel
you made my day. spent ages doing that Q like hours and hours just seraching what i was doing wrong. thanks again.
this forum rOcks!

Please,do not double post.You should have asked it in one single forum.I think Classical Physics was the appropiate choice...

Daniel.

## 1. What is the Gibbs free energy change for ethanol?

The Gibbs free energy change for ethanol, also known as the change in standard Gibbs free energy of formation, is the difference in energy between the reactants and products of the reaction that produces ethanol.

## 2. How is the change in Gibbs free energy for ethanol calculated?

The change in Gibbs free energy for ethanol can be calculated using the equation ΔG = ΔH - TΔS, where ΔH is the change in enthalpy, T is the temperature in Kelvin, and ΔS is the change in entropy. Alternatively, it can be looked up in a table of thermodynamic values.

## 3. What does a negative change in Gibbs free energy for ethanol indicate?

A negative change in Gibbs free energy for ethanol indicates that the reaction is spontaneous and exergonic, meaning it releases energy. This means that the reaction will proceed in the forward direction without the need for external energy input.

## 4. How does temperature affect the change in Gibbs free energy for ethanol?

Increasing the temperature will make the change in Gibbs free energy for ethanol more negative, indicating a more favorable and spontaneous reaction. This is because the increase in temperature causes an increase in the entropy term in the equation, making the overall change in Gibbs free energy more negative.

## 5. What factors can affect the change in Gibbs free energy for ethanol?

The change in Gibbs free energy for ethanol can be affected by the concentrations of reactants and products, temperature, and pressure. It can also be influenced by the presence of catalysts, which can lower the activation energy and make the reaction more favorable.

• Thermodynamics
Replies
11
Views
435
• Classical Physics
Replies
1
Views
2K
Replies
3
Views
968
• Quantum Physics
Replies
12
Views
796
• Atomic and Condensed Matter
Replies
1
Views
855
• Classical Physics
Replies
15
Views
5K
• Biology and Chemistry Homework Help
Replies
1
Views
2K
• Chemistry
Replies
11
Views
2K
• Biology and Chemistry Homework Help
Replies
2
Views
2K
• Introductory Physics Homework Help
Replies
9
Views
6K