CHEMISTRY COMMUNITY

Patricia Chan 1C

In lecture today, Lavelle went over an example question where he asked whether the acid was neutral or negatively charged at pH=6 based on the pKa value of the acid. Could someone explain why exactly it would be negatively charged? Thank you!

Patricia Chan 1C

Thank you for that clarification. How does one determine if an anion is more stable than another?

Patricia Chan 1C

According to Lavelle's syllabus, you need a 50% to pass with a C-. Hope this helps!

Patricia Chan 1C

Could someone clarify how to determine acid strength? Lavelle mentioned in lecture that HF < HCl < HBr < HI; why exactly is that? Thank you!

Patricia Chan 1C

They use that resonance structure because the formal charge is lower! Hope this helps.

Patricia Chan 1C

Reading the textbook is always a good way to reinforce information, especially since a lot of the midterm questions were conceptual. Attending step up sessions and workshops are always really helpful to practice. Hope this helps!

Patricia Chan 1C

Both are correct! Lavelle seems to like the notation with d in the beginning. Either way, you wouldn't get marked down for using one instead of the other. Hope this helps!

Patricia Chan 1C

Water can act as both a proton acceptor and a proton donator. It can both accept a proton and become a hydronium ion (thus acting as a base), and donate a proton and become a hydroxide ion (thus acting as an acid). Hope this helps!

Patricia Chan 1C

I think the best way to determine ion charges is just to memorize them :/ it's a bit tedious, but if you just go through some flashcards with them you'll be able to familiarize yourself with them in no time. Hope this helps!

Patricia Chan 1C

Yes! I believe the list of strong bases is a bit longer than that of strong acids, but the same concept applies. Hope this helps!

Patricia Chan 1C

Most acids are considered weak because few acids actually fully dissolve into ions. It would be easiest to just memorize the strong acids (for example HCl, HBr, and so on) to understand which ones WILL fully dissolve. If an acid isn't a part of that list, it's likely a weak acid.

Patricia Chan 1C

I believe that if you attend workshops that are run by the TAs, they will give you worksheets to work on for practice.

Patricia Chan 1C

Weak acids will have higher pH values than strong acids. A weak acid is an acid which partially dissociates into ions in an aqueous solution, while a strong acid will fully dissociate into ions. A common example of a weak acid is acetic acid. HCl is a common example of a strong acid.

Patricia Chan 1C

I think it's best to memorize all of them. He just exemplified how we can figure out the shapes in lecture from the basic ones.

Patricia Chan 1C

They are different shapes! Trigonal planar has three regions of electron density, all being bonded pairs. Trigonal pyramidal has four regions of electron density, but with three bonded pairs and one lone pair. Hope this helps!

Patricia Chan 1C

It will be on material from after the midterm. And the test will be during Week 8 in your discussion. Hope this helps.

Patricia Chan 1C

No, it should only cover material from after the midterm! Hope this helps.

Patricia Chan 1C

Yes, ideally the central atom should have a formal charge of 0. This is because we want the central atom to be the least electronegative atom of the molecule.

Patricia Chan 1C

I would do all of the homework problems that are assigned, as I found that very helpful for preparing for tests. Additionally, the review sessions and step-up workshops are always a great resource and provide a different perspective on the material to be learned. Hope this helps!

Patricia Chan 1C

If I recall correctly, Lavelle said he would be returning them this coming Wednesday. Hope this helps!

Patricia Chan 1C

I believe he will be showing the average sometime in lecture this week.

Patricia Chan 1C

I'm thinking that turning in Chem Bonding questions would make more sense since we haven't actually gone over any new Chapters/materials. Hope this helps!

Patricia Chan 1C

I believe it will only cover what we learn after the midterm. If he does include anything from before, it may just be chemical bonding topics. Hope this helps!

Patricia Chan 1C

I feel like going through the concepts in the book is always helpful to clarify any questions you may have on topics. I think practicing is the biggest thing you can do to prepare. Go through the assigned homework problems as well as any practice midterm questions (like the dino nuggets questions) t...

Patricia Chan 1C

Atomic weight is quite literally the weight of an atom, and this is given on the periodic table so you won't have to calculate it yourself. As for molecular weight, this refers to the mass of a given molecule, which can contain many atoms. To find the molecular weight, you would add the atomic masse...

Patricia Chan 1C

Yes the trend continues! Hope this helps.

Patricia Chan 1C

It will be everything covered in lecture up until the very last slide on Friday's lecture. In other words, Fundamentals, Quantum, and some of Chemical Bonding. Hope this helps.

Patricia Chan 1C

Lavelle said it would be everything covered in lecture up until the very last slide on Friday's lecture. Hope this helps.

Patricia Chan 1C

Hi there! I highly doubt we will be tested on it on the midterm because we did not go over it in lecture. I believe he mentioned that sometime in lecture. Hope this helps!

Patricia Chan 1C

The only thing about length mentioned is that we will be given two hours to take the exam (from 6-8).

Patricia Chan 1C

I think your best bet would be checking out test banks that have previous exams so you have some sort of idea of what kind of questions will be asked. I think going over all the assigned problems would be a good idea as well.

Patricia Chan 1C

I believe it will cover the quantum chapter and perhaps the bonding chapter (correct me if I am wrong). Beyond that, I'm not too sure what format it will be, but I think it would be reasonable to assume that the difficulty of the qs would be alike to the difficulty of the qs from the first test!

Patricia Chan 1C

He doesn't post his slides, sorry.

Patricia Chan 1C

Ionic bonds are formed between metals and nonmetals in which electrons are lost and gained. Covalent bonds occur between nonmetals and nonmetals in which electrons are shared.

Patricia Chan 1C

Hey! I think Bozeman science makes really wonderful videos that are often times very insightful and extremely helpful. I use them a lot, and I think they've really helped my understanding of chemistry. Hope this helps!

Patricia Chan 1C

Hi there! First off, quantum numbers don't necessarily "do" anything but they do play an important role in helping us identifying the position and orientation of electrons. l describes the shape, and it can be any number that is n-1. m labels different orbitals of a subshell (orientation),...

Patricia Chan 1C

Hey! I've been making sure that I watch the online modules and then completing the post assessments first in order to see what topics are my strengths and what topics are my weaknesses. After, I make sure to do all the homework problems Dr. Lavelle assigns, and I go over them again to make sure I ac...

Patricia Chan 1C

Molarity as a unit is defined as moles per liter (mol/L). Molarity is basically the concentration. The higher the concentration, the more solutes are present in the solution. Hope this helps!

Patricia Chan 1C

I believe the x is representative for the plane. There are three planes, x, y, and z. Hope that helps.

Patricia Chan 1C

Hey there! I think watching the modules online and then doing the post assessments as a form of self evaluation is really helpful. After doing that, I do all of the textbook practice problems and ensure that I understand how to work through literally all of them. The textbook excerpts can also be he...

Patricia Chan 1C

Molarity and Dilution problems will be on the test as it was a part of the concepts that we went over in the Fundamentals chapter. I would say to just practice the problems in the G section of the assigned homework, and you'll be prepared.

Patricia Chan 1C

My TA did not ask for our Bruincards specifically, but you do need to be able to write your school ID on the test. So either have that memorized, or bring your Bruincard for reference.

Patricia Chan 1C

You'll need to know combustion reaction reactants and products. Other than that, our TA mentioned that any other molecular formulas that may be more complex are usually given to you on the test. That being said, it might be a good idea to eventually memorize polyatomic ions and understand how to for...

Patricia Chan 1C

We're only going to be seeing material from the Fundamentals Section on Test 1-- so no quanta and photons!

Patricia Chan 1C

Yes, you will be provided with a periodic table which includes atomic masses for the test!

Patricia Chan 1C

First, find the molar mass of H20 (this should be 18.002g). Then, divide by Avogadro's number to convert into grams per mole.

Patricia Chan 1C

You want to use Avogadro's Number in order to convert mols into atoms, molecules, or formula units. If the question wants you to do this, it will specify that they are looking for such units (atoms, molecules, formula units etc).

Patricia Chan 1C

Thanks so much for the refresher on sig fig rules! In number one, however, I think 5293 has four sig figs instead of five. Nonetheless, thanks again!

Patricia Chan 1C

You do five problems total! It's advised to do more than the required five problems for practice though.

Patricia Chan 1C

(c) How many moles of water molecules are in 5.15 g of Epsom salts? I've been told that I should multiply 7 by (5.15g/246.48mol) to obtain the number of mols of water molecules; that being said, I can't exactly pinpoint why this is the way to solve this problem. Could anyone explain step by step how...

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