CHEMISTRY COMMUNITY

1K Kevin

YES this finally made sense to me now thank thank you so much! i could never tell when to flip or not thank you!

1K Kevin

Final will be on all material throughout the quarter, TA said that it will probably be around 8 questions, some may have multiple parts, and you can expect at least 1 question from each topic. Online Lavelle also states that "Questions will come from the Homework and Online Assessments" ho...

1K Kevin

I believe he said that he will post the problems and answers later tonight! As for other notes he did: he went over the equations we will need to use (all of which can be found on the equations sheet) and gave more detail of when to use each

1K Kevin

"Calculate the potential of a cell constructed with two nickel electrodes. The electrolyte in one compartment is 1.0 M Ni(NO3)2. In the other compartment, NaOH has been added to a Ni(NO3)2 solution until the pH = 11 at 298 K. Use Table 6I.1" The problem is uses the Nernst Equation but Im c...

1K Kevin

As far as I know you do not include H2O since it is a pure liquid while you would include H+ or OH- since those are aqueous solutions

1K Kevin

Yup from Gibbs free energy to but not including the Nernst Equation. I was told it will probably have 8 questions and be half thermodynamics and half electrochemistry but that might not be exact ¯\_(ツ)_/¯

1K Kevin

The cathode is the reduced half-reaction as seen in how it gains electrons in the process. The anode is oxidized in its half-reaction as seen in how it loses electrons in the process.

1K Kevin

I was told all content from weeks 6 and 7 and since the midterm was week 6 wednesday we only have friday week 6 and week 7

1K Kevin

I can't really say everything that won't be given on the midterm but this is all the equations and constants he will give us, plus he said to give us constants specific to the problems. You might have to use variations of these equations but hope this helps! https://lavelle.chem.ucla.edu/wp-content/...

1K Kevin

The one that starts with 6 is 6.01 kJ*mol^-1. This is per mole and the one Lavelle used is per gram and isn't given to us on the constant sheet. The two options here are to remember and use that one for this problem or convert the grams of ice to moles and use the 6.01kJ/mol (If you convert to moles...

1K Kevin

Thank you thank you for all this :D

1K Kevin · Re: Lecture notes 2/8/19 Yooo this is super useful thank you thank you

Yooo this is super useful thank you thank you

1K Kevin

Not sure but if you go the step-up/workshop sessions you can probably get some more focused worksheets

1K Kevin

Part b asks "How much heat is absorbed in the oxidation of 5.45L of nitrogen measured at 1 atm and 273k?" The only thing I can think of is to use the ideal gas law because we have p v and t but that gives the the moles and where do we go from there?

1K Kevin

Adiabatic is a quick process that does not allows for heat transfer, but the temperature pressure and volume can all change. All change in energy would be from Work.

1K Kevin

The volume is held constant, on a PV diagram it would a vertical line meaning the pressure and temperature can change. Since it is a vertical line there is no work being done and the change in internal energy is all heat.

1K Kevin

The pressure is constant. On a Pressure-Volume Diagram the line would be a horizontal line

1K Kevin

No he doesn't. You could get the notes from someone and I'm sure he could clear up any confusions you still have in like office hours or something :)

1K Kevin

Work is not a state function because its current state depends on things preceding it. The example in the book is two experiments, one where a gas expands pushing a piston which pushes against water; work is done here because there is an external force. The second has a gas push a piston into a vacu...

1K Kevin

A closed system has a fixed amount of matter but can exchange energy with the surroundings/environment. In an isolated system the system can't exchange matter or energy with the surroundings.

1K Kevin

I'm getting a bit confused but what does a high pKa mean in comparison to a low pKa, and same with pKb. I know that a low pKa means a high pKb but would that be a stronger acid/weak base or a stronger base/weak acid.

1K Kevin

If you look on the example 5I.3 7th ed on p.419-420 you see in the change portion of the ICE that there can be a +2x or -2x. These come from the stoichiometric coefficients of the chemical equations

1K Kevin

Autoprotolysis is the proton transfer between the same type of molecule. In the case of water it favors being 2H2O rather than being H3O+ and OH-. This leads to autoprotolysis for water at 25 C being 1*10^-14 with H3O and OH being equal

1K Kevin

For the midterm it took them like a week so I assume that it will be posted around Next Sunday
Good luck with finals! :D

1K Kevin

The real mvp here

1K Kevin

Does anyone have any notes they can share for the review session that was on Tuesday 12:30-2 pm with Daniel, wasn't able to go because of work so thank you very much!

1K Kevin

Dr. Lavelle i just want to say that having chemistry community has been a huge help in helping me succeed. Some topics have been harder than others but having this resource always with me is a huge help.

1K Kevin

The last day of instruction will be Friday of week 10 but the last day of new material will be Wednesday week 10. Friday will be a review session during class like how it was for the midterm

1K Kevin

Brushing up on Outline 3 would't hurt since its on the test still.

1K Kevin

just came to say WOOOO NO CLASS WEDNESDAY!

1K Kevin

I challenge myself to do the harder homework problems and when I can't solve one I look at notes and online videos for that section

1K Kevin

They can be used in the same context, but specifically I believe bent is for when the general shape is distorted by lone pairs

1K Kevin

I think memorizing them would help especially knowing the bond angles for the each one.

1K Kevin

Ya! We didn't really cover too much of outline 4 yet so Outline 3 stuff would be fine. Plus its always extra practice for the final

1K Kevin

Can anyone help explain the process for 11a
Thank You!

1K Kevin

Hi,
Elements that are in period 3 and up can have expanded shells that hold more than 8 but will they always have more or when can they?

1K Kevin

Under what tab is last year's midterm in ccle?

1K Kevin

Can someone help me with part A. Its given "the velocity of an electron is emitted from a metal surface by a photon is 3.6 x 10^3 km * s^-1 and are trying to find the wavelength of the ejected electron" Im having a hard time figuring out what equations to use or the steps to solving it. Th...

1K Kevin

Thank you!! These were extremely helpful clarifying!

1K Kevin

I've heard many days but I'm sticking to Sunday which I heard the most. So long as you do 3 a week you should be fine :)

1K Kevin

Can someone explain when I should use the equation v = R * ( 1/n1^2 - 1/n2^2) and how does this relate to energy and the atomic spectra

1K Kevin

This is some reassuring stuff, Thanks!

1K Kevin

We'll be given one form of equations so you'll need to be able to switch it up for what you need. We'll also have all the constants like c h R and a periodic table

1K Kevin

The units of the numerator are J *S which is (kg*m^2*S^-2) *S
The denominator for it is (kg)*(m*S^-1) If you move the s^-1 to the numerator (1/s^-1 = s^1/1) the you get s^2 *s^-2 which will cancel the seconds and the kilograms

1K Kevin

Is there a specific due date for the first 4 modules or are they just help for our test.

1K Kevin

I believe that those would count since the first turn in isn't until Sunday so everything before that should count.

1K Kevin

Addition and subtraction takes the Least significant figures after the decimal point. In this case, I think that one of the reasons is that you can't accurately say that the answer is 123456.608 because the .6 means that you estimated the measurement to .5 through .7 (or +/- .1). So if you keep the ...

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