CHEMISTRY COMMUNITY

Ruth Rosales 3D

A lower pKa value indicates a stronger acid

Ruth Rosales 3D

It is by the formal charge which is found with:

F = VE - Nonbonoding e - (total # e shared in bonds)/2

Ruth Rosales 3D

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

Ruth Rosales 3D

I kinda minimized the steps of naming the compound into a couple words if it helps. I wrote: 1. cation, 2. complex(ligands+transition metals), 3. anionic ligands, 4. prefixes, 5. ligands in alphabetical order, 6. transition metal with oxidation state, 7. anion. Just remember the subtle rules in bet...

Ruth Rosales 3D

Hi Ruth! I also had trouble with naming coordination compounds and I honestly don't have any shortcut methods. The way I have been learning is just LOTS of practice to get the rules in my head. Good luck! It's nice to know that I am not the only one who struggles with this. Sometimes it's easy to f...

Ruth Rosales 3D

I normally say it is 106 because I figure that it is safer to use what they give us in class, however, I do see how this value could be affected by the properties of the compound as other people have said.

Ruth Rosales 3D

I know that it is mainly used to describe acids, but apart from that, I am not really sure what it means.

mono = one?

Ruth Rosales 3D

Amphoteric - react as an acid and a base
Amphiprotic - donates and accepts protons

Hope this helps

Ruth Rosales 3D

I think it is helpful to be very familiar with a list of strong acids and bases and then those that are not found on either list can be classified as weak. I mainly meant that in the question it is already known that all the acids/bases listed are strong but I have difficulty determining how to ran...

Ruth Rosales 3D

How do we determine the formula of the conjugate acid/base?

I know that they are two substances that differ by one proton, but sometimes when I calculate it based on this fact, I don't always get it right.

How can I fix this inconsistency?

Ruth Rosales 3D

Sometimes we were given a list of all strong acids but among them, I didn't really know how to determine which one was strongest.

Ruth Rosales 3D

pKA = -log (Ka)

If you are missing other values, this is how to find them:

Ka = [H+][A-]/[HA]

1.0 * 10^-14 = [OH+][OH-]
14.00 = pH + pO
pH = -log [H+]
pOH = -log [OH-]

Ruth Rosales 3D

I always make it C in the center with a lone pair.

Ruth Rosales 3D

Do you guys have any additional tips on naming compounds? I know the general rules for naming them, but I take too long to determine the name.

I would like to be faster in a test setting. So, if you guys have any shortcuts, I would love to hear (see) them.

Thank you.

Ruth Rosales 3D

What would be the coordination number for: [Co(SO4)(NH3)5]+ My initial thought would be 5. But it marks it as wrong. I do struggle to find the coordination number, but sometimes I do it wrong, any tips on how to make the process easier? Also: One of the times I counted I got six but I am not sure ho...

Ruth Rosales 3D

Hi, I had this question too so I googled it.

There are a lot of available charts with the abbreviations for chemical compounds. It would be helpful to save one of these charts as a future reference.

As mentioned in other replies, (en) is for ethylenediamine (H2NCH2CH2NH2).

Ruth Rosales 3D

You don't alphabetize by the prefix, you do it by the ligand. Then you add the prefix.

Ruth Rosales 3D

Having difficulties answering the following question: Which geometry or geometries are common for complexes with a coordination number of 6? trigonal bipyramidal hexagonal planar octahedral pentagonal pyramidal I answered it to be: octahedral and pentagonal pyramidal, but it is marked as wrong. Coul...

Ruth Rosales 3D

None of them are resonance structures to one another. To have resonance, they must check the following:

- same molecular formula
- same atom connectivities
- same overall charges
- same number of electrons

Ruth Rosales 3D

Saw the post about bond order.

I thought bond order was only 1, 2, and 3. How can I determine that the bond order is 0, wouldn't that mean that is not bonded at all?

Ruth Rosales 3D

How do we come to determine the smallest bond angle?
Based on one of the questions from Sapling week 8.

Are we meant to memorize the angles for each shape? Because that is how I've been answering these questions.

How do you guys usually approach questions like these?

Ruth Rosales 3D

This is done like any other lewis structure (anyone correct me if I am wrong) - Count the number of electrons in the molecules - The carbons will be thee center atoms - Follow the octet rule They are very similar and only differ in the number of carbons. From there you should be able to observe how ...

Ruth Rosales 3D

For lewis acids and bases, I know that overall they are differentiated between electron acceptor and donor. I usually determine this by the overall charge of the ion that is given (either - or +) but it does not always work. I am having trouble looking at the ions as a whole, so could anyone walk me...

Ruth Rosales 3D

Some clarification needed.

If a highly electronegative atom bonds with an atom with low electronegativity, what does it mean for the electronegativity of the molecule overall?

Ruth Rosales 3D

As I review for the final, I am having some trouble deriving the chemical reactions out of word problems. I understand how to balance them, but I am not sure when it would be combustion, single replacement, double replacement etc. Is there a trick to memorizing these patterns or something else. Also...

Ruth Rosales 3D

Sometimes I get the shapes of the molecules wrong. I usually go by how many atoms surround the central atoms, mainly because I am not sure how double and triple bonds affect the structure.

Any tips/information that can help me?

Thank you.

Ruth Rosales 3D

This is how I am memorizing it:

- single bond = 1 sigma bond
- double bond = 1 sigma and pi bond
- triple bond = 1 sigma and 2 pi bonds

so each bond has one sigma bond and the pi bonds go increasing from double to triple bond by 1.

Hope this helps

Ruth Rosales 3D

None of them are resonance structures to one another. To have resonance, they must check the following:
- same molecular formula
- same atom connectivities
- same overall charges
- same number of electrons

Ruth Rosales 3D

Can anyone define/clarify cyclic structures? I went back on my notes but they were not that clear. I need this in the context of the following sapling question for week 8: "Draw the three possible structures of C3H4 . Be sure to include all atoms." I already got the two linear structures b...

Ruth Rosales 3D

Hi, you should apply skills from previous sections. In this case, you should determine the molecular formula which can be done by first looking for the empirical formula. (You can find it by assuming that there is 100g of the compound) After finding the molecular formula, you can draw the lewis stru...

Ruth Rosales 3D

Having trouble with this question: "A 3D representation of a cyclohexane ( C6H12 ) molecule, a cyclic compound used in the manufacture of nylon and found in the distillation of petroleum, is shown. Name the geometry around each carbon atom." I thought it might be tetrahedral or trigonal py...

Ruth Rosales 3D

I'm not sure if this question belongs in this section.

If the formula for the tetrahydridoborate ion is H4B, how do the charges determine this?
My understanding is that Hydrogens expected charge is +1 and Borons is +3

Ruth Rosales 3D

Still struggling with some of the electron configurations. This is the question: Give the ground-state electron configuration and number of unpaired electrons expected for each of the following ions a) Sb 3+ --> answer: [Kr] 4d105s2 b) Sn 4+ --> answer: [Kr] 4d10 d) Br - --> answer: [Kr] e) Ni 2+ --...

Ruth Rosales 3D

It means that there are non-valence electrons, so the overall charge of the structure of the ion is written outside the brackets.

Ruth Rosales 3D

Hello! The way I am memorizing it is: Acid Accepts and Bases donates (electrons)

It basically just works for the acids but I remember that Acid and Accepts starts with the same letter.

Ruth Rosales 3D

The lower the formal charge, the lower amount of electrons need to be redistributed in the forming of the Lewis structure. So, the lowest the formal charge is the most plausible.

Ruth Rosales 3D

I am unsure of how to approach the following question: The chlorine–oxygen bond length in the perchlorate ion is found experimentally to be 144 pm for all four bonds. The average length of a Cl−O bond is 172 pm and the average length of a Cl=O bond is 140 pm . Which of the Lewis structures of the pe...

Ruth Rosales 3D

Sapling Homework #5

HCNO Resonance structure A

I am having trouble using the formal charge formula for this structure, the results I get are marked as wrong, so I must be doing something wrong.

Ruth Rosales 3D

Hi,
While I was working on the homework a lot of my problems originated from wrongly converting equations. This occurred with equations as simple as E = hc/lambda

Any tips?

Ruth Rosales 3D

Having some trouble with the following question:

A violet line is observed at 434.0 nm in the spectrum of atomic hydrogen. Determine the values for the beginning and ending energy levels of the electron during the emission of energy that leads to this spectral line.

Thanks in advance.

Ruth Rosales 3D

Thank you. You saved me a late night.

Ruth Rosales 3D

I got a notification at the bottom of my CCLE page that it will be in maintenance mode in a few hours, does anyone know how long it will last? I still have a couple of questions to complete and personally, I can only access sapling through the CCLE link so if I can't access it I can't finish my home...

Ruth Rosales 3D

This was such a clear explanation thank you so much! I understand now.

Ruth Rosales 3D

Consider a single photon with a wavelength of λ, a frequency of v, and an energy of E. What is the wavelength, frequency, and energy of a pulse of light containing 100 of these photons? The answer is λ, v, and 100E I would be lying if I said I didn't make a lucky guess and got it right. Can anyone e...

Ruth Rosales 3D

This is more like a studying strategy that has worked for me. I do all the textbook problems leaving some space and don't look at the answers until the end. The ones that I get wrong I go back and cross with a different color the steps I did wrong. I redo the problem and write down what I missed and...

Ruth Rosales 3D

I am having a hard time understanding what it means by the ground state of the Carbon atom. The answer to its ground state is 1s^2 2s^2 2p^2 but shouldn't it be 1s^2 2s^2 2p^1 3s^1 since that is 6 electrons?

Ruth Rosales 3D

I just wanted to get some more insight into the experiment that determined their model. In high school, I never understood why shooting the alpha particles to the aluminum helped them. Even with the visuals.

Ruth Rosales 3D

Thank you, this helped a lot.

Ruth Rosales 3D

So technically, this reply comment wouldn't count?
I just want to verify, I don't accidentally want to miss easy points for the class. Thank you.

Ruth Rosales 3D

Do comments count towards the 5 points/posts we are supposed to do weekly? I've been counting them as part of mine.... :/

Ruth Rosales 3D

Under the Quantum World Outline, the problems listed to do are for "Focus 1" which I assumed is chapter 1 since it has the same title. However, there is no 1A and 1B, it's just 1.n. Any guidance? I have a hard copy of the sixth edition, can that be the problem? I do have access to the 7th ...

Ruth Rosales 3D

Calculate the amount (in moles) of (a) Cu^2+ ions in 3.00 g of CuBr2 The first time I solved this question, I moved on because my response matched. However, now that I am reviewing the questions I am rethinking why is the answer 0.0134 mol of Cu^-2 and not 0.0134/2 mol of Cu^-2.? 3.00 CuBr2/223.35 g...

Ruth Rosales 3D

Hello!

When solving a problem, I use the periodic table given in the cover of the textbook. Regardless of the sig. figs. in the problem, I use the full value when doing the math, and once I get the final answer I round it up to the sig. figs. given in the problem.

Ruth Rosales 3D

The .23 grams of 3-methyl-3-hexanol is the actual yield of the reaction. Percent yield = (actual yield)/(theoretical yield), so I believe you can derive the percent yield with the theoretical yield you calculated and the actual yield given in the problem. I did, it gave me 69% but sapling didn't ta...

Ruth Rosales 3D

Having some trouble in #10 I was able to calculate the theoretical yield but now to calculate the percentage yield I don't know which value is the ACTUAL yield. I got the theoretical yield to be 3.3x10^-1 so I divided that by the 0.23 g of 3‑methyl‑3‑hexanol produced (given). Am I supposed to derive...

Ruth Rosales 3D

During discussion, my TA mentioned that you should always use the whole value available throughout solving the problems to assure accuracy. Once you've arrived to the final solution, round up to the number of sig. figs. given in the problem. Hope this helps.

Ruth Rosales 3D

From what I've been understanding from the readings, a formula unit refers to mol.
(Correct me if I'm wrong)

Ruth Rosales 3D

Left this one for last because I did not really know how to change moles into distance/length.
Could anyone lead me in the right direction to solve it?

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