CHEMISTRY COMMUNITY

MackenziePerillo-1L

It all just clicked, thanks .

MackenziePerillo-1L

Can anybody explain where the equation Ln(k'/k) = Ea/R ((1/T)-(1/T')) came from? Thanks!

MackenziePerillo-1L

I do not know exactly where you are going wrong, but I would make sure that you are using parentheses in the e expression: e^(-Ea/(RT)). I would also write out all of the units of what you are solving to make sure that they all cancel out to get you the desired units of k.

MackenziePerillo-1L

yes, they are comparing experiments 1 and 3 if the problem you are talking about also corresponds to problem #15.17 in the 6th edition book.

MackenziePerillo-1L

Generally when solving these types of problems, I try to compare two experiments where only one variable is changing. For example, when trying to figure out the order with respect to reactant B, I would compare two experiments with the concentrations of A and C held constant. Therefore, you can easi...

MackenziePerillo-1L

Because exothermic reactions are spontaneous, they occur naturally. Therefore, generally exothermic reactions have a very low activation energy barrier when compared to endothermic reactions, as it takes very little input of energy for the reaction to occur.

MackenziePerillo-1L

I believe Dr. Lavelle sent out an email with a link that answers this exact question :)

MackenziePerillo-1L

Simply put, catalysts are not consumed in a reaction whereas intermediates are. In other words, intermediates are formed and used up, where as catalysts are not consumed and are there from the beginning.

MackenziePerillo-1L

I believe that the regular integrated rate law usually works with problems that have set concentrations and a set amount of time, where you are manipulating known variables to solve for an unknown in the problem. I believe the exponential decay formula you are referring to might be a derivation/mani...

MackenziePerillo-1L

I'm still a little confused on this concept on determining the rate. In lecture, we said if [A]0 >> [B]0 and [C]0 then rate = k'[A]^N. Why do we use k' instead of k? k' is generally used instead of k to symbolize the rate of the reverse reaction, as to your specific question, A is probably in the p...

MackenziePerillo-1L

Do you mean when finding the initial reaction rate instead of the initial order?
If this is the case, the initial rate would be the constant, k * concentration of H2 *concentration of I2, being as it is a second order process for the reaction, with first order in respect to both reactants.

MackenziePerillo-1L

Can somebody explain how to do the problem: Write the half reactions and draw a galvanic cell diagram to study the following reaction:
H+ (aq) +OH- (aq) ---> H20 (l)

MackenziePerillo-1L

Also knowing this topic helps to understand where some of the equations are derived from, kind of like what Dr. Lavelle does in lecture when he goes through the derivation of an equation.

MackenziePerillo-1L

Raj_Bains_2C wrote:Thermodynamics only cares about the initial and final states, while kinetics focuses on the pathway of the reaction.

Thermodynamics only cares about the initial and final states unless you are considering heat and work, both of which are not state functions

MackenziePerillo-1L

Is there any way to get access to the worksheets distributed at these sessions if we missed this week?

MackenziePerillo-1L

Hello, I believe for part A it is positive because it is the entropy for the surroundings which are gaining the heat given off the body. Hope this helped! I agree with this statement because you want to focus on the surroundings gaining entropy instead of doing what I initially did by looking at th...

MackenziePerillo-1L

You can also use the equation
delta S= nR ln (P2/P1) to calculate the entropy change for an isothermal increase in pressure.

MackenziePerillo-1L

Thank you that was really helpful and clarified so much.

MackenziePerillo-1L

Can anyone clarify how equilibrium can shift when pressure is increased in a reaction involving different amounts of moles of gas making up the products and reactants?

MackenziePerillo-1L

0K will additionally almost never appear in nature, therefore when referring to entropy at 0K, it is mostly used for conceptual limits.

MackenziePerillo-1L

I am still confused as to when each equation for work is supposed to be used.
w=-p* Δv
w= - v1∫v2 Pdv
w=-nRT ln (v2/v1)

Can anyone specify in which type of case each equation is used?

MackenziePerillo-1L

I am still confused as to when each equation for work is supposed to be used.
w=-p* Δv
w= - v1∫v2 Pdv
w=-nRT ln (v2/v1)

Can anyone specify in which type of case each equation is used?

MackenziePerillo-1L

Also, a bomb calorimeter, an isolated system, will always have constant volume.

MackenziePerillo-1L

would this be an example of an irreversible system?

MackenziePerillo-1L

Is a reversible system always isothermal?

MackenziePerillo-1L

Is the only example of an isolated system a calorimeter?

MackenziePerillo-1L

Are both bond enthalpy and bond energy always positive?

MackenziePerillo-1L

Bond enthalpy is always positive because it is the energy put into breaking a bond, which is an endothermic process (energy is being put in).

MackenziePerillo-1L

Does it matter what our alias is?

MackenziePerillo-1L

Will the reverse reaction always be doing more work than the forward reaction?

MackenziePerillo-1L

Thank you so much for this advice, it is super helpful to hear from someone who is actually going through the process.

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