CHEMISTRY COMMUNITY

Izamary Marquez 2H

Biohackers! Also I personally am very interested in CSI and Forensics so shows like Criminal Minds and Bones are go to's :)

Izamary Marquez 2H

My TA recommended focusing on the textbook problems/readings!

Izamary Marquez 2H

Also,s hould we memorize which of these groups in particular affect pH? Or is there a general rule we can apply?

Izamary Marquez 2H

In addition is there a certain way we should approach every problem whether it is negligible or not? Should we always solve for it anyway?

Izamary Marquez 2H

Also, can someone explain how the relationship Q>P means products are favored (I understand it's because the numerator is higher) but I am confused on how this tells us the direction of the reaction and what it really means regarding the stability of the reaction. If someone could explain the correl...

Izamary Marquez 2H

Endothermic reactions absorb heat from the surrounding environment. So if heat is added, then there is a lower activation energy for the reaction to occur.

Izamary Marquez 2H

This is the class groupme! https://groupme.com/join_group/62288203/dSSkobMS

I am not sure if you meant that or a specific one for your discussion..Hope it helps!

Izamary Marquez 2H

In addition, could someone give me an example of a heterogenous equilibrium? I am confused on how we could have one or more product/reactant in "different phases" or what that really means in the context of a reaction.

Izamary Marquez 2H

Because the equilibrium concentrations of CO and H2O are 0.100-X (according to the ICE table), X cannot equal 0.126 or else the concentrations would be negative. For problems like these, I would look at the two solutions and see which one makes sense since one of the solutions will result in a nega...

Izamary Marquez 2H

is finding the conjugate acids and bases different for each type of acid and base based on whether they are lewis or not? I would say yes. There are definitely patterns you can turn to, but it really depends which molecules are interacting, so it's best to look at which molecule is donating and whi...

Izamary Marquez 2H

Ruth Rosales 3D wrote:Usually, I determine the oxidation number from the charge of the atom.

For example: MgCl2
Knowing that Cl = -1
Mg + 2Cl = 0
Mg + -2 = 0
Mg = +2

Hope this helps

Do we always assume that the oxidation for Cl is -1 because that's its more stable state?

Izamary Marquez 2H

Can someone explain how a more stable atom creates a molecule that is more acidic? If it has a higher electronegativity, wouldn't that mean that it holds on to the H+ atoms more strongly, therefore making it harder to release them? Thanks!

Izamary Marquez 2H

Also, I am a little confused on how we know whether it's 100% associated... Can we determine this based on the Lewis Structure of the molecule? In general, what does it mean for the acid to be "completely associated"?

Izamary Marquez 2H

In addition to this, I was wondering if the relationship pH<pKa is ALWAYS true for weak acids, or if there are certain exceptions we should remember.

Izamary Marquez 2H

It helps me to look at the individual charges and then the sumo them! The oxidation number refers to the charge on the ion. In addition to this question, are there trends with oxidation numbers that make them easier to memorize?

Izamary Marquez 2H

I heard that it should be fixed by 10pm but same! :/ I had issues accessing them on CCLE when I used Safari, but it looks like Chrome did the trick! Maybe try that.

Izamary Marquez 2H

A helpful method for me is to review the earlier material by going over practice problems for each section. If I am confused on a topic I will spend more time reviewing that. As far as practicing this week's material it is really helpful to reread your notes after each lecture to take in everything ...

Izamary Marquez 2H

Yeah it should be Wednesday!

Izamary Marquez 2H

I got one from my discussion section that was really helpful!

Izamary Marquez 2H

I got one from my discussion section that was really helpful!

Izamary Marquez 2H

In addition to this, if a molecule is rooted, would the axial and equatorial planes be the same? In other words, are the axes consistent or are they always with regards to the vertical and horizontal planes?

Izamary Marquez 2H

It really helps to study/work in a space where I will not get distracted. Going outside and away from distractions at home truly helps! Also, there are several study playlists on Spotify :) I find instrumental music really helps me stay focused!

Izamary Marquez 2H

I don't think we need to know what specific kind of reaction each one it; it will likely be stated. But as for combustion reactions, I remember Lavelle stating that it occurs when oxygen is a reactant and water and hydrogen are products (with heat being produced).

Izamary Marquez 2H

In addition to this question, do the formal charges change significantly when there is a delocalized bond? Or would it generally be the same?

Izamary Marquez 2H

It helped me to draw out the dipole arrows! You will see that they point in opposite directions, which cancel out the distribution!

Izamary Marquez 2H

Are hydrogen bonds ALWAYS present in N,O,F atoms? or is this just likely where they are to be found?

Izamary Marquez 2H

In the equation for the dipole moment= charge x bond length, will we be given the charge or how would we calculate it?

Izamary Marquez 2H

Does the number of electrons in an expanded octet depend on the block that the atom is in?

Izamary Marquez 2H

I'm sure there are many different ways to draw molecules. Much of the information regarding this will likely come with more lectures and knowledge about molecule shape, because we just began exploring that topic!

Izamary Marquez 2H

That is correct! Usually I start by drawing out each atom (its symbol) and then drawing the number of valence electrons. After that, I draw the bonds and assure that the atom has a full octet!

Izamary Marquez 2H

In my personal experience, I post in the topic that's most related, but I saw that someone posed a question regarding the Rydberg equation in the announcement section! But if you cannot find the topic that's most related, I would just post it in a section that's faintly similar because I know some ...

Izamary Marquez 2H

In addition, when calculated a dipole moment, will |q| always be given?

Izamary Marquez 2H

Would this make cations and anions more likely to be acids or donors? Is there a correlation?

Izamary Marquez 2H

The lewis structure for SO4 should have an overall of charge of -2. Sulfur can form up to 6 bonds given that it has 6 valence electrons. Sulfur double bonds to two of the oxygen atoms (giving those oxygens a 0 formal charge) and single bonds to two other oxygen atoms (giving those oxygens a -1 form...

Izamary Marquez 2H

I start with the octet rule and then use formal charge to check over my work, and if there are any charges that needed to be added I will add them. It is helpful to use both, but you should start with the octet rule. I do this as well to make sure I don't leave out any electrons! However, I was uns...

Izamary Marquez 2H

In questions about drawing the Lewis structure of an atom, the questions usually refer to "additional Stability"...What does this mean? Is this only with regards to resonance?

Izamary Marquez 2H

It is of course best for the whole structure to have a formal charge of 0, but if that doesn't happen, i think the second most stable form is when the central atom has a formal charge of 0. As you make the charges of the outer electrons zero, wouldn't this start to make the central atom's charge al...

Izamary Marquez 2H

With this being said, the closer the elements are in electronegativity, the more affinity they have, correct? I remember Lavelle saying something about this but I can't remember the exact rule..

Izamary Marquez 2H

Hello, I had a question regarding the electrons filling up different levels of the p-orbital.. Why can other orbitals have up to 8 electrons on their outermost energy level but the in the p-orbital they fill up x, y, and then z spaces of that orbital?

Izamary Marquez 2H

With regards to cations and anions, is there a certain periodic table pattern as to where they happen to appear more frequently? What does this telling about their bonding properties and does this have anything to due with their electronegativity?

Izamary Marquez 2H

With regards to cations and anions...Is it possible for them to have the same 4 quantum numbers considering they will have different properties than expected and they are altered?

Izamary Marquez 2H

After reading these comments I am still confused... What does it mean for the electrons to be "parallel"? Does this change the atoms/molecules that they are likely to bond with?

Izamary Marquez 2H

I may be wrong, but I remember Lavelle saying that even though the d orbital is listed before the s-orbital, it is technically last... With this being said, wouldn't that mean that it has 10 valence electrons?

Izamary Marquez 2H

One thing that works for me is to first draw out every atom with all the electrons as dots and THEN draw the bonds so that I don't get confused :)

Izamary Marquez 2H

With regards to Carbon, Lavelle mentioned that e- occupy the 2Px1 orbital and then occupy the 2Py1 orbital... Is this always the case? Or does this only happen when it comes in contact with a certain atom/molecule?

Izamary Marquez 2H

You would just use the Heisenberg Uncertainty Equation! When it says "minimum uncertainty", just know you can assume the change in momentum X change in distance are EQUAL to h/4pi! In general however, you will just use the same formula (with the knowledge we have at the moment).

Izamary Marquez 2H

With regards to diffraction, how can we tell when a system is constructive vs destructive? Do these properties mean something in particular? Is there certain characteristics of atoms that make the waves have one pattern over the other?

Izamary Marquez 2H

With regards to energy levels in the Balmer or Lyman series, is there a specific reason why the energy is negative. For example, E4=-1/16hR and E2=-1/4hR. Is this because the light is being emitted and energy is released?

Izamary Marquez 2H

I believe the issue has been fixed now!

Izamary Marquez 2H

Once you have your equation for the reaction balanced out, you need to look at the ration of one molecule to the other (if there's two i.e this case). Then, once you solve for the actual amount, whichever one limits the ratio it should have is the limiting reactant.

Izamary Marquez 2H

You can use a blank piece of paper to do your work, but my TA said you do not have to submit it! And yes, the exam will be multiple choice, likely with no partial credit.

Izamary Marquez 2H

In the experiment, was there a specific reason why they used metals (mainly copper) to reflect the e-. In addition, can an experiment like this one be both classical & Quantum mechanics by changing a few variables of the experiment.

Izamary Marquez 2H

Why is it that the Balmer series only goes to n=2? Is this just what is visible to the naked eye? In that case, wouldn't everyone see a different portrayal

Izamary Marquez 2H

In lecture, Lavelle mentioned once the energy of e- on the second energy level matches that of the first, the electron is excited. However, I was under the impression that one energy level had to be completely full before e- proceeded to the next energy level. Can someone explain what he meant by th...

Izamary Marquez 2H

In one of his first lectures, Lavelle mentioned that the chemical formulas will be provided for us in tests.

Izamary Marquez 2H

Can you explain what you mean by "the pattern"?

Izamary Marquez 2H

Britney Tran IJ wrote:so the chemistry community posts are due on Sunday at midnight instead of Friday right?

Yes! the Chem Community and HW are both due on Sunday night

Izamary Marquez 2H

Hi guys! There is a groupie me for discussion 2L.. and not many have joined. Thought I would share the link on here!

https://groupme.com/join_group/63062393/OTZeg2L7

Izamary Marquez 2H

Just a general question about the conversion of grams to moles and mL to L... I know we usually have to change the grams to moles as a first step to proceed with he problem, and with regards to molarity, we will likely be dealing with Liters.. However, I keep getting different answers due to the fac...

Izamary Marquez 2H

A solution is prepared by dissolving 55.1 g of KCl in approximately 75 mL of water and then adding water to a final volume of 125 mL. What is the molarity of KCl(aq) in this solution? A. 0.169 mol.L-1 B. 10.8 mol.L-1 C. 0.0923 mol.L-1 D. 5.91 mol.L-1 I'm a bit confused in the wording of this questio...

Izamary Marquez 2H

In lecture, Lavelle explained that we will not know if the formula we have concluded is the empirical or molecular formula until we are given the molar mass of the molecule. Will we always be given the molar mass? If not, should we just assume that the formula is the empirical formula?

Izamary Marquez 2H

In a combustion reaction, when C burns in the presence of O, why is CO2 always a product? And same with H20? Is there a specific reason why this occurs?

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