CHEMISTRY COMMUNITY

Ally M

We can tell that a reaction will be spontaneous solely based on the fact that delta g is negative. Gibbs free energy already takes enthalpy and entropy into account, so if we are given Gibbs free energy we already know.

Ally M

Degeneracy is the number of possible variations a system can have that all have the same energy level.

Ally M

It all depends on the symmetry of the Lewis diagram, asymmetrical compounds will have residual entropy, but symmetrical ones will not.

Ally M

When enthalpy is negative, meaning it is exothermic, delta G has a higher chance of being negative, and therefore spontaneous.

Ally M

Although it is usually the case that spontaneous reactions are endothermic, there would still have to be a negative delta g value. This value relies on delta h and s as seen in the equation ΔG = ΔH - TΔS.

Ally M

You use these values for Cp and Cv for ideal monatomic gases.

Ally M

When we have a system that is under constant external pressure, we can use the equation w = -p(delta V) to calculate work. Used when there is constant external pressure or when volume changes

Ally M

The pH scale ranges from 1-14, where 14 is basic and is acidic. pH measures the concentration of H+ ions within something to determine the strength of the solution.

Ally M

When there are no solid metals on the anode or cathode sides of the cell diagram, we have to use an electrode like Platinum. Platinum must be in the cell with the half-reaction that has no conducting solids. Other than that, the electrodes are usually written on the far left and far right.

Ally M

equation wise this is the relationship, pKa = -log[Ka] and Ka = 10^-pKa. The larger the Ka value, the smaller the pKa value and stronger than the acid is. The relationship is similar to the relationship between pH and H+

Ally M

thank you, Dr. Lavelle, even though I was never able to attend your lectures in person, I can tell you care so much about your students and their success, both in your class and beyond. You put so much time and effort into this class, more than I have ever seen from another professor. I wish you all...

Ally M

Even though the final is over now, treat your self to something nice, whether it be food, some rest, or your favorite movie :) Just know that this one-grade wont make or break your future!

Ally M

Happy quite late valentines day :)

Ally M

since breaking a bond requires energy, it is endothermic.

Ally M

in short, an extensive property is just one that depends on the amount of substance (mass or volume)

Ally M

heat capacity is always positive because it is the amount of energy required to increase the temperature of a substance. Additionally, that process is endothermic.

Ally M

R is the ideal gas constant, R = 8.314 J·K-1·mol-1, but you can change it to fit whatever units you are working with.

Ally M

thank you for your help :) I finally got it!

Ally M

since energy is being lost from the surroundings, there would be an energy increase on the system, meaning it would be positive.

Ally M

Does anyone know if we will be able to leave the zoom call for the final once we are done, like we have for the other ones??

Ally M

I have the same question, any help would be appreciated!!

Ally M

In this case, n is the number of electrons transferred in redox reactions.

Ally M

If the redox reaction is correct, you should be able to cancel out the electrons from both sides. You need these electrons in the half-reaction in order to balance out the charges of all reactants and products, but you don't need to include them in your final product.

Ally M

Intermediates get canceled out as they show up on the product's side of one reaction the reactant's side of another reaction. The intermediate is necessary if the reactants cant leads to the products directly.

Ally M

No, it can be either one :)

Ally M

Yes, the standard unit for temperature is kelvin, so use that in all equations.

Ally M

delta G is spontaneous when it is negative. Can someone explain the difference between this and delta G naught again?

Ally M

Instantaneous is calculated at a very specific point in time, like the slope of a tangent line, and the average rate is the change over a longer period of time.

Ally M

I didn't realize taking 14B and Bl at the same time was doable, so I'm taking 14BL in the spring then waiting till fall to take 14c since I am still struggling in this class.

Ally M

1/K :) thank you!

Ally M

They are both different units of measurement, despite being quite similar. You just have to make sure to convert to atm because that is the unit of the R constant.

Ally M

They are solved the same way expect Kp is used when you are dealing with pressure and kc is used for concentrations, and you will obviously be dealing with different units.

Ally M

We probably know by now that K is when the reaction isn't at equilibrium, but I think the important part to remember is that when Q=K, it is at equillibrium.

Ally M

It starts off high as the concentration is the highest, then will decrease eventually to o.

Ally M

I liked equilibrium from this year, but I finally learned how to correctly balance a chemical equation this quarter so yay

Ally M

Thank you for clarifying that it was first-order reactions only!!

Ally M

I keep getting stuck on the second part of this question, I doubled checked my work and made sure that I converted everything correctly, does anyone have any suggestions for mistakes I cold have made?

Ally M

Hi, thank you for the help, but I am still a little confused on how to find the k value, since I solved it slightly differently finding the Ea/RT value first.

Ally M

For this question, I first took the natural log of both sides, then the common log, and then just substituted the rest of the values into the Arrhenius equation!

Ally M

Here is another graph that may be helpful :)

Ally M

Thank you! It's just because it will increase the rate constant of the one with greater activation energy correct?

Ally M

these helped me alot but I am still confused if part 5 should be numeric or not

Ally M

the potential difference is proportional to the resistance of a circuit. "EMF is a potential difference which is created when no current is flowing in the system" From my understanding EMF and the potential difference can sometimes be used interchangebly.

Ally M

I'm confused as to what you are asking, if you are asking why we need Pt in part b, it is because iodine is a nonmetal so it doesn't conduct electricity.

Ally M

^^^ I agree with this I still am not sure why is shows that as the answer.

Ally M

thanks for the answers!
I get that it's a single compound and that it would apply to the whole thing, but why does it make a difference with/without the brackets?

Ally M

I believe it will also be in the same format as Midterm 1, online with proctorio and zoom.

Ally M

In a reversible process, the entropy will be 0 as long as the state stays the same, there is no heat transfer, and there are no external processes affecting it. In general, the entropy of an irreversible reaction increases in both the system and its surroundings. All real processes are irreversible.

Ally M

if there is no change in the state of the system or no external effects on the system it will be 0. obviously, in order to have an entropy of 0, there cannot be any heat transfer, meaning that they have to be the same temperature.

Ally M

Or you can find ΔS1 of the entropy for heating water to 100C, ΔS2 which is the molar entropy for vaporization of water at 100C, and the ΔS3 which is the entropy for cooling water to 25C. Then find the total ΔS by adding them all together.

Ally M

I understand the topic and the process behind it, but can someone explain why there is no P in the answer for B?

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