CHEMISTRY COMMUNITY

joycelee1A

I remember that on the test we took on kinetics, when asking for half time, the question specifically asked for the answer to be in seconds. So, probably, the best would be to use seconds unless the problem specifically asks for another measurement of time to be used.

joycelee1A

A nucleophile is a chemical species attracted to positive charges. Therefore, they would be negatively charged.

joycelee1A

Raising the temperature raises the rate constant as well.

joycelee1A

From my discussion section, on the reaction profile, our TA defined the difference in energy between the reactants and products as the ∆G (in reference to kinetics). Activation energy is the minimum energy required for the reaction to take place. I don't think we defined much of a relationship betwe...

joycelee1A

Akash_Kapoor_1L wrote:Do we have to know how to calculate the limiting step for test 3? Which hw problems focus on the limiting step?

I don't think so. Dr. Lavelle said test three would go up to 15.6, and this topic isn't on there.

joycelee1A

Any of the experiments should work for finding the rate constant.

joycelee1A

No, I don't think you would be able to do that for an overall reaction. The example you gave was for a bimolecular elementary step in which then I think your assumption may be correct.

joycelee1A

The textbook defines molecularity as the number of reactant molecules or species taking part in a specified elementary reaction, so I would think that it has to do with the elementary step and not the overall reaction.

joycelee1A

I don't think so since zero order reactions don't have to do with the concentration of the reactants.

joycelee1A

A zero order reaction is when the rate is independent of the reactant concentration. From what I remember, they occur most often when the reaction is catalyzed. So, zero order reactions usually/most often happen with a catalyst involved. For example, if a substrate attaches to the activation site of...

joycelee1A

I believe that the rate law is in reference to the reactants. For the coefficients, I think it has to do with the way the rate is defined. Like coefficients matter in the equation where rate=(1/a)d[A]/d[t]. Besides this equation, I'm not too sure about the coefficients.

joycelee1A

From what I remember from during my discussion section, the more positive potential means its a greater oxidizing agent and after the potential, the size would be the next determining factor.

joycelee1A

The method we learned today in class was the method of using initial rates. You set up a ratio of concentrations and rates of two of the experiments to the equation rate=k[A]^n and then solve for n which makes the ratio true.

joycelee1A

It means that doubling the concentration for a second order reaction should increase the reaction rate by four times the original reaction rate. So mathematically, since the concentration is being raised to the second power, doubling it would cause it to be 2^2 or times 4.

joycelee1A

You use single lines between different states and a comma for multiple species in the same state.

joycelee1A

I don't have a direct conceptual answer, but there were two equations given which both have pressure and the equilibrium constant which solves for Free energy. ∆G=nRTln(P2/P1) (for pressure) and ∆Go=-RTlnK.

joycelee1A

If you think about a spontaneous natural process of heat flowing from a hot region to a cold region, the entropy for the hot region would be S1=q/T. The entropy for the cold region would be S2=q/T. So if you calculate ∆S=S2-S1, ∆S is positive since T2<T1. There was an increase in the entropy of the ...

joycelee1A

Degeneracy is the number of ways a given energy state can be achieved. I think one way is you can raise the number of states possible to the number of atoms. So if there were 2 states possible and 3 atoms, it would be 2^3.

joycelee1A

I think you use Q when the system is not in equilibrium.

joycelee1A

Can someone explain more concisely why a process produces maximum work in a reversible reaction? I don't fully understand why.

joycelee1A

The textbook mentions a Clausius Inequality, ∆S≥q/t. Could someone explain the importance for it and what it is saying about the reaction? (Also do we need to know about it for the class?)

joycelee1A

Heat is not an intrinsic property and depends on the path of the reaction. Tt occurs when there is a change in the system. Heat provides information on how the final state was attained not just the final and initial state. The energy transferred through heat does depend on how it is transferred, and...

joycelee1A

I don't fully understand the two equations of 3/2R and 5/2R, or why they are the equations for the heat capacities of a monatomic gas and linear molecule. Do we have to necessarily know this information?

joycelee1A

Why is the temperature constant in reversible reactions whereas temperature changes along the path for irreversible reactions?

joycelee1A

I'm not sure about all the details of it, but I do know that with solids and liquids, the volume can't really change and there's no expansion work being done. Since the pressure is constant, and liquids and solids aren't compressible, the volume isn't changing either.

joycelee1A

I didn't fully understand 8.39. The question asks for the amount of heat needed to convert 80.0g of ice at 0 °C into liquid water at 20°C. Would there be a calculation for phase change we need to take into consideration? I wasn't sure how to go about it.

joycelee1A

My TA mentioned it too. I'm not entirely sure, but my TA mentioned that it would be a closed system with no heat transfer.

joycelee1A

Can someone explain how bomb calorimeter works, and would we need to know technically how it works?

joycelee1A

The energy used to otherwise increase the temperature (specific heat) is instead used to change phases (heat of fusion). Once the temperature for the boiling point or melting point is reached, the energy that would have raised the temperature goes into changing the phase.

joycelee1A

If you think of it from a mathematical standpoint, you can substitute ∆Hfus and ∆Hvap with their equations to get the original ∆Hsub equation. ∆Hfus=Hliquid-Hsolid and ∆Hvap=Hvapor-Hliquid. So if you substitute it, ∆Hsub= (Hliquid-Hsolid) + (Hvapor-Hliquid). The Hliquid cancels out leaving Hvapor-Hs...

CHEMISTRY COMMUNITY

Search found 30 matches

Re: Rate Unit Conversion

Re: Nucleophile

Re: The Effect of Temperature

Re: Gibbs and Activation Energy

Re: Limiting Step

Re: Rate Constant

Re: Rate Laws of Elementary Reactions

Re: Molecularity

Re: Pseudo Zero Order Reactions

Re: Catalysts

Re: Rate Law [ENDORSED]

Re: Reducing Agent/ Oxidizing Agent

Re: Reaction order

Re: Doubling Concentration in Second-Order Reaction

Re: Cell diagram [ENDORSED]

Re: Free Energy, pressure, and equilibrium constant

Re: Entropy Concept

Re: Degeneracy

Re: When to use Q versus K [ENDORSED]

Work and Reversible Process [ENDORSED]

Clausius Inequality [ENDORSED]

Re: State properties of heat and enthalpy

Heat Capacities of monatomic gas and linear molecule

Reversible Vs Irreversible

Re: P delta V is significant?

8.39

Re: Adiabatic [ENDORSED]

Bomb Calorimeter

Re: Temperature during phase changes [ENDORSED]

Re: ∆Hsub= ∆Hfus+ ∆Hvap