CHEMISTRY COMMUNITY

Lynsea_Southwick_2K

How do you know that it is a neutral solution?

Lynsea_Southwick_2K

He pulls questions from the homework, online assessments, and chemistry community- so keep that in mind!

Lynsea_Southwick_2K

What section covers deprotonation?

Lynsea_Southwick_2K

Acidic solutions: balance O by using H2O, then H using H+
Basic solutions: balance O using H2O; then H using H2O (FOR EACH H) to the side of each half rxn that needs H and adding OH to the other side

Lynsea_Southwick_2K

Zero-order: a rxn for which the rate is independent of concentration of the reactant (Rate= k x (concentration)0 = k)

Lynsea_Southwick_2K

If conversions are correct you should be fine, but I would keep in mind what units the problem gives.

Lynsea_Southwick_2K

Last quarter w Lavelle, same grading system, I ended with 344/500 and that resulted in a C. I think it depends on the class averages.

Lynsea_Southwick_2K

What I do is write all of the exponents even if it is 0 or 1, but then I simply further and would take out the value to the 0 as it would be 1, and I would not write to the first power.

Lynsea_Southwick_2K

15.17 The following rate data were collected for the reaction 2A(g) + 2B(g) +C(g) -> 3G(g) + 4F(g): Initial concentration (mmol.L^-1) Experiment [A]v0 [B]v0 [C]v0 Initial rate((mmol G).L^-1.s^-1) 1 10. 100. 700. 2.0 2 20. 100. 300. 4.0 3 20. 200. 200. 16 4 10. 100. 400. 2.0 5 4.62 0.177 12.4 ? a) wh...

Lynsea_Southwick_2K

Do you work backwards for part c? I am not sure what to do.
I have the rate of reaction of NO2, I know the coefficient of NO2 is 2.
Do I divide 6.5 x 10^-3 by 2? How does that give the unique rate of the whole reaction?

Lynsea_Southwick_2K

I did one half rxn in regards to the Cl2(g) and then the other in regards to H2(g), then when you combine the half rxns you get 2H+(aq) and 2Cl-(aq) on the product side which is also 2HCl

Lynsea_Southwick_2K

Basic solutions: balance O using H2O; then H using H2O to the side of each half rxn that needs H and then adding OH to the other side.
If there ends up being H2O on both sides you simplify

Lynsea_Southwick_2K

(left) Anode: oxidation half rxn
(right) Cathode: reduction half rxn

Oxidation: Loss of e-
Reduction: Gain of e-

Lynsea_Southwick_2K

I think this is a typo!

Lynsea_Southwick_2K

Step 1 : identify whats being oxidized/reduced (Oxidation: Loss of e- → reducing agent, Reduction: Gain of e- → oxidizing agent) Step 2 : write the 2 skeletal, unbalanced equations Step 3 : balance all except O and H Step 4 : Acidic solutions: balance O by using H2O, then H using H+ Basic solutions...

Lynsea_Southwick_2K

In the 6th edition textbook on page 569 it states "Galvanic cells are also known as voltaic cells."

Lynsea_Southwick_2K

If you mean oxidation numbers, these are the ones I try to keep in mind:

Hydrogen in all compounds is +1
Hydrogen in hydrides -1
Oxygen in peroxides -1
Group 1 elements in compounds +1
Group 2 elements in compounds +2
Halogens in group 1 and 2 compounds -1
Monoatomic ions same as their charge

Lynsea_Southwick_2K

How do we know which one to add out of Pt(s) or C graphite?

Lynsea_Southwick_2K

He recently updated the given equations/constants page on the website, I assume that is what he is giving us for the test today. I suggest taking a look and to see if there are any you should remind yourself of. I noticed that the delta S vaporization and delta S fusion equations are not given to us...

Lynsea_Southwick_2K

On the Midterm important info it states, "Questions will come from the Homework, Online Assessments, and Chemistry Community."

Lynsea_Southwick_2K

At least one question comes from the homework problems given.

Lynsea_Southwick_2K

I would suggest looking at the given constants/equations sheet so you know which ones are given versus ones you'll need to remember. From my experience with Lavelle's tests, they do not specifically ask "state the definition of ___", although it is important to know when to use what and wh...

Lynsea_Southwick_2K

Which lecture was the cutoff one for the midterm? Will there be material from 2/8/19 lecture on the midterm since that is the one that touched on gibbs free energy?

Lynsea_Southwick_2K

cp would be different for copper and water. Cp copper = o.38 J/Celsius*g and cp water is 4.18 J/Celsius*g

Kobe_Wright wrote:What would cp be in this equation?

Lynsea_Southwick_2K

As defined in the textbook an open system can exchange matter and energy

Lynsea_Southwick_2K

Between going over notes, the modules, the homework problems you should be good to go. If you have any doubts utilize the normal weekly sessions and even the midterm review sessions.

Lynsea_Southwick_2K

For the change in volume (V2-V1) is it 2.4-1.2 or 1.2-1.2? What values do you get for part a and part b? The second experiment does more work because all energy is going into moving the piston (none is going into increasing the temperature because the experiment is an isothermic expansion). You can ...

Lynsea_Southwick_2K

Maybe because of sig figs its 6.8? It is weird that the book states 6.80

Lynsea_Southwick_2K

Since it is composed of two different equations on the table, how does that work?

Lynsea_Southwick_2K

Please post the question!

Lynsea_Southwick_2K

What is the units for momentum, p?

Lynsea_Southwick_2K

You go from grams to moles and then look at the moles required from the equation and multiply those values.

Lynsea_Southwick_2K

I think it is still viewed out of 500.

Lynsea_Southwick_2K

Thank you for arranging so many sessions for us I greatly appreciate it.

Lynsea_Southwick_2K

will I get partial points for getting the reactants right but not the product?

Lynsea_Southwick_2K

Because of the length of the bond

Lynsea_Southwick_2K

How would we see the Lyman and Balmer series on the final?

Lynsea_Southwick_2K

Personally I have to draw out the lewis structure so I can physically see the vsepr model (the AXE form).

Lynsea_Southwick_2K

4.15 Write the Lewis structure and the VSEPR formula, list the shape, and predict the approximate bond angles b) TeCL4 Te has 6 e-, Cl has 7e- times 4 = 28e-. 28+6= 34e-. Lewis structure must have 34e-. Lewis Structure: Te is the central atom, there are 4 Cl's around the Te, they all connect with a ...

Lynsea_Southwick_2K

The second rule of the VSEOR model is: "Rule 2 There is no distinction between single and multiple bonds: a multiple bond is treated as a single region of high electron concentration. That is, the two electron pairs in a double bond stay together and repel other bonds or lone pairs as a unit. T...

Lynsea_Southwick_2K

Thanks for this.

Lynsea_Southwick_2K

I think BH2- has 6 electrons. B has 3, H2 has 2, and since it has the - charge it adds another electron, adding up to 6.
So the VSEPR formula would be AX2E1.

Lynsea_Southwick_2K

What helps me is looking at the VSEPR formula. They are distinct from one another.

Lynsea_Southwick_2K

You look at the givens and determine the one with the least amount of sig figs. Your answer should reflect that number of sig figs.

Ex: givens 5.12345, .00000023, and .12.
The least amount of sig figs is 2 in .12
So your answer should have 2 sig figs.

Hope this helps.

Lynsea_Southwick_2K

The last time I have seen electron configurations I was a sophomore in high school, when we first saw them in lecture I was very lost. I have tried watching videos to teach myself about them and I thought I started to understand but I was confused again when it came to the shorthand way of writing i...

Lynsea_Southwick_2K

Wait do we need to memorize these conversions? Do we also need to memorize the frequency conversions such as what one joule is in etc? I don't think we need to memorize these ones specifically, I asked my TA and he said we are going to see some prefixes more then others- like pico and nano. These o...

Lynsea_Southwick_2K

Hello, I'd like to share how I remember unit conversions: King Henry Died Monday Drinking Chocolate Milk KHDMDCM Kilo Hecto Deka [Meters(liters/grams)] Deci Cent Mili 10^3 10^2 10^1 10^0 10^-1 10^-2 10^-3 The "Meters" section is also covers liters and grams. There is no prefix I know of fo...

Lynsea_Southwick_2K

Would n never equal 4 or anything more then 3?

Lynsea_Southwick_2K

Will Monday's lecture be on the test?

Rachel Dang 1H wrote:Blackbody radiation should not be on the test next week, the material that we have covered including today's lecture will be though.

Lynsea_Southwick_2K

I saw this in the bundle that was recommend. But I got the textbook alone, do I have to invest in this?

Lynsea_Southwick_2K

It's a good idea to pick 1 or 2 problems from not so current lectures as it keeps old info fresh in mind.

Lynsea_Southwick_2K

904837647 wrote:What's the late policy for hw? I couldn't find it on Lavelle's syllabus, maybe i just missed it but I didn't realize hw was now being collected during discussion.

I had to speak to my TA about this, explain your confusion and maybe they will work with you or tell you what you should do.

Lynsea_Southwick_2K

If the value was 1.37 and it has to be multiplied to get closer to a whole number, what would you multiple it by? x 3 would equal to 4.11, but x 2 would be 2.74.

Lynsea_Southwick_2K

And remember to use the least amount of sig figs from the given info.

Lynsea_Southwick_2K

Helen Mejia 3F wrote:Hey, so consider using Avogadros number (6.022 x 10^23) and multiplying it by twice the radius (which would be 288 pm).

6.022 x 10^23) Ag x (288 pm x 10^-12)= 1.73 x 10^14

Why do you multiply the radius twice?

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