CHEMISTRY COMMUNITY

Amy Zhang 1I

adam_simshauser_1l wrote:Does anyone have the link to the answer key for the practice final by any chance?

It's the PDF he uploaded in this thread right under the test link

Amy Zhang 1I

Hi, the anode is usually on the left and the cathode is usually on the right. However, if you want to make sure, just remember that the anode is losing electrons or giving them away, and the cathode is the one gaining the electrons or receiving them. Since cathodes are receiving the electrons, this ...

Amy Zhang 1I

I think the main thing to study for this is knowing a general idea of what your weak bases and acids are. You should already know the strong bases/acids, so anything compounds that are not a part of the list is automatically a weak acid or base. Something I have noticed is that if there is an H at t...

Amy Zhang 1I

From my understanding, the voltage will remain constant no matter how many electrons pass through. This is because it is like a standard voltage and the frequency of how many electrons go through will not change the standard voltage

Amy Zhang 1I

In this question, I found Z to be 0. When I move on to try to solve for y, I became stuck because there are no two reactions that are constant for both x and z to solve for y. Can we disregard the inconsistencies in the C concentrations when solving for Y because rate order for Z is 0? This would me...

Amy Zhang 1I

Hi! I have heard from friends that reading the textbook has helped a lot for concepts if you have not done so already. There are a lot of conceptual details in there that are skipped over in lectures or assignments. Additionally, I also go to the Peer Learning sessions that Lavelle organized for us....

Amy Zhang 1I

For open systems, we can assume all three factors can change because heat and energy can exchange between the systems and surroundings. Closed and isolated systems would be more limited, as some factors cannot change.

Amy Zhang 1I

When work is done by the object, it is negative. On the other hand, when work is done by the surroundings and onto the system, it is positive.

Amy Zhang 1I

Hi! The way I think of zero-order reactions that help me visualize the graph is a linear graph. The zero order rate has no ln or fractions, which means it will be linear opposed to a non-linear or exponential graph like the other rate laws. A1= -kt+A0 essentially translates to y=-mx+b, so it would b...

Amy Zhang 1I

Hi! Can someone please reiterate the importance of a slow rate in the context of the reaction? It was briefly covered in Jillian's session today and I forgot. From what I can remember, we only use the slow reaction rates? How do we know whether it is a slow or fast reaction?

Amy Zhang 1I

The rate (k) integer itself may be positive, but in every rate law equation, we can see that it is always associated with a negative sign. Ex: -k(t) + A0. -K would then represent m, a negative slope.

Amy Zhang 1I

Hi! I just wanted to clarify whether it was 4 extra posts per week or a total for 4 extra posts through weeks 8-10 that would allow us to reach the 4 extra credit points. Thanks!

Amy Zhang 1I

Hi there! The anode is usually on the left side whereas the cathode is on the right. Anodes become oxidized, which means it loses electrons and are the ones donating them. Cathodes receive the electrons, so it gains electrons.

Amy Zhang 1I

If balanced correctly, there should only be one possible n number because they are the same! Hope this helps.

Amy Zhang 1I

Hi! N represents the number of electrons transferred in the equation. They are the same for each half-reaction so I would advise finding n in the half reaction that seems the most simple. For example, in diatomic atoms or elements that are not in a compound in the products to reactants would be most...

Amy Zhang 1I

Work on a system would mean the system gains energy, so a negative value (work is done, it gets pushed in --> smaller --> negative value). Work done by the system means it does work, so a positive value occurs (it pushes out --> bigger --> positive)

Amy Zhang 1I

Cv is used when there is a constant volume and Cp is used when there is a constant pressure. There are different values for each, however depending on the atom. If Cv is linear, we use 3/2R, and 5/2R for nonlinear molecules

Amy Zhang 1I

Hi! Enthalpy is used to measure heat within in a system and entropy is the disorder. So a liquid to gas requires heat (positive H) and also increases disorder as it goes from liquid to gas because molecules move more around in the gas (positive S)

Amy Zhang 1I

Hey so degeneracy (W) can be calculated in E^a, where E= possible energy orientations and a being the molecules. If there were 8 molecules with three orientations, W would be 3^8. This is because there are 8 molecules and each of the 8 has its own 3 orientations, hence to the power.

Amy Zhang 1I

They are only equal when under constant pressure!

Amy Zhang 1I

Exothermic = energy released = bonds form = products>reactants.
Endothermic = energy absorbed/needed = bonds break = reactants>products

Amy Zhang 1I

Cp is constant pressure whereas Cv is constant volume. Hope this helps!

Amy Zhang 1I

It typically does not matter, just ensure the rest of your units check out.

Amy Zhang 1I

I believe it is due to the fact that everything that occurs is known so far to stay within the same universe. We do not know if our universe would affect outside universes, if it can at all.

Amy Zhang 1I

A high Ka and Kb correlate to a stronger acid or base. pKa and pKb in a sense are inversely related to the strength of acids and bases, so a higher pKa or pKb indicates a weaker acid and base.

Amy Zhang 1I

I am not sure how you got 2.5 as n, but I left n as 5 mols and ended up with 122 atm.

Amy Zhang 1I

I wanted to clarify if we needed to do 3 posts/week for full credit, week by week, or a total average of around 3/week for full points. In other words, are the 3 per week to help us stay on track? Or as long as we hit the threshold for an average of 3/week, we get full credit? Thanks!

Amy Zhang 1I

You need to go to settings and change your profile name from your UID to discussion and name! And they should all link

Amy Zhang 1I

I am very confused on how to write the chemical equations. For example, NaCH3Co2 needs to be broken into N+ and CH3OO-. We use CH3OO- because it is a weak acid since N is a strong base if mixed with OH. We would then write the equation to be CH3COO- + H2O --> Ch3COOH + OH-. However, I thought becaus...

Amy Zhang 1I

I have a pH of a weak base of C3H7Nh2 at 11.86, and I am trying to find values of Kb of C3H7Nh2. I can calculate the Ka by 10^-11.86 to get a Ka of 1.38x10^-12. Can I just use the Kw equation to calculate Kb, and then use -log Kb to find pKb? Can someone let me know if these steps are correct? Thanks!

Amy Zhang 1I

Yes, it is possible! Upon downloading it will last you up to four years, which you can use to study for other tests such as the MCAT. Click on resources through Achieve. Hope this helps!

Amy Zhang 1I

Can someone give me a quick easy refresher on how to determine whether a compound is an acid, base, or neutral? I know it involve periodic table groups, but I need clarification. Thanks! Ex: KCl, K2SO3, etc.

Amy Zhang 1I

Calculate the molar concentration of Ba(OH)2 and the molar concentrations of Ba2+, OH-, and H3O in an aqueous solution that contains 0.43 g of BA(OH)2 in 0.100 L of solution. I know that we have to find the M for BAOH2 first which is 0.025, but how do we use that to find concentrations of Ba2+ and O...

Amy Zhang 1I

Hi! As long as other variables are constant, an increase in moles, or n, will cause an increase in pressure given the equation.

Amy Zhang 1I

You can increase reaction speed through many factors such as heat, and concentrations of reaction.

Amy Zhang 1I

Hi! This information is usually given in the problem and/or the equation, denoted by little subscripts. (l) would represent liquids, (g) for gas, and (s) for solid.

CHEMISTRY COMMUNITY

Search found 36 matches

Re: Arthur's Final Exam Practice

Re: Cathode/Anode Right and Left

Re: determining if something dissolves under acidic or basic conditions

Re: Reduction Potential Doesn't Change

HW 10 Q7

Re: HOW TO STUDY FOR FINAL

Re: Open Systems

Re: Explaining work

Re: zero order reactions and graphs

Slow Reaction Importance

Re: Rate of reaction

Extra Credit Chem Community

Re: Cathode vs Anode

Re: Which "n" value do we use for G = -nFE? [ENDORSED]

Re: Finding the n in the Nernst Equation

Re: Work on a system vs by a system

Re: Cv and Cp for Ideal Gases

Re: Enthalpy vs Entropy

Re: Calculating W

Re: Delta H at constant pressure

Re: bond strength correlation to exothermic or endothermic

Re: Cp and Cv

Re: K or Celcius

Re: Universe as a system

Re: What does pKa, pKb, Ka, and Kb say about the strength of acids and bases.

Re: Calculation without Kp

Chem Community

Re: New account for Chem 14B?

Writing Chemical Equations: Weak acid = H30 and Weak base = OH-?

Calculate using Ka or Kb?

Re: Textbook Inquiry [ENDORSED]

Acids and Bases

Textbook Problem 6A.23 Step 2

Re: Change in Pressure

Re: Reaction Speed

Re: Solvent vs. Aqueous Reactant?