CHEMISTRY COMMUNITY

DominicMalilay 1F

Usually when you need to find the concentration of a compound, use the ice chart. When finding the Kc value you'll need the concentrations in order to plug your values.

DominicMalilay 1F

The most common mistake on this one is forgetting to inverse the function if it is in the wrong order! You need to find the reciprocal to do this.

DominicMalilay 1F

Make sure that the p/r, the values are the power of the coefficient in the chem rxn! This is essential to solve the problem.

DominicMalilay 1F

Being more general, Q is the more specific term compared to K which specifies a specific instance in the rxn!

DominicMalilay 1F

When doing the problem, make sure you know Q= products/reactants. The coefficients turn into powers and just plug in the values they give for the compounds!

DominicMalilay 1F

In terms of pure stability, q and k have no effect on one another because they are separate variables that assess different values of the reaction.

DominicMalilay 1F

Since the factor affecting the concentration is not the volume, and volume changes concentration, then it will have no effect!

DominicMalilay 1F

The exact effect would require calculations and since we are just doing general trends it will not be tested!

DominicMalilay 1F

Non-ideal gases are not tested for this course because it isn't on the syllabus or lecture!

DominicMalilay 1F

Pressure and volume always have an inverse relationship.

DominicMalilay 1F

The large k value is usually for 10^3 while small k value is 10^-3!

DominicMalilay 1F

Only include it for gases because solids and liquids are not a part of the ice table!

DominicMalilay 1F

I personally never keep my units in celsius for the t variable as its just easier to remember!

DominicMalilay 1F

I think it's just the opposite of the ionic character!

DominicMalilay 1F

Count lone pairs and regions of electron density. A double bond is still 1 region of electron density as is a single or triple bond.

DominicMalilay 1F

I make sure to count the electrons and remember that the charge of the overall molecule matters for adding/subtracting electrons!

DominicMalilay 1F

Its the same table as the one we used for the 2 midterms!

DominicMalilay 1F

It exists because of naturally existing chemicals in the atmosphere (CO2,SO2) forming acids in the presence of water, making the rain slightly acidic.

DominicMalilay 1F

How do you determine the shape of this molecule? Also, how do you know that the compound's formula is SOCl2 from the name of the compound? This was a sapling problem

DominicMalilay 1F

What VSEPR shapes do we have to memorize for the exam?

DominicMalilay 1F

I always thought they are interchangeable. Wikipedia says "The oxidation state, sometimes referred to as oxidation number," so I think they are the same!

DominicMalilay 1F

The excess energy is thought of as kinetic energy because excess energy is transferred into the electron to give it the energy to move from the metal. Hence, it is kinetic.

DominicMalilay 1F

The photoelectric effect was focused on electrons emitting from metals, but there could be a correlation with the structure of the metals (with different alloys and so on) which can have an effect on the amount of electron emission. It's a stretch, though.

DominicMalilay 1F

In a double or triple bond, where would the sigma bond be in relation to the pi bond, and vice versa?

DominicMalilay 1F

Yes, along with others the main point is that it would be bound to a transition metal for it to be called a ligand.

DominicMalilay 1F

How would coordination numbers work for more complex and lengthy ions? For example Ba[FeBr4]2?

DominicMalilay 1F

Also,w remember that the types of bonds in a real molecule are not actually there; the atoms are just arranged to maximize efficiency. A molecule with a single and double bond in its lewis structure has the same bond lengths in real life!

DominicMalilay 1F

Types of bonds do not change the shape of the molecule! It would only be for lone pairs or the number of separate bonds.

DominicMalilay 1F

Because of the lone pairs forming electron repulsion, it takes on a bent shape.

DominicMalilay 1F

Even though it is an ion, the charges cancel so it is nonpolar.

DominicMalilay 1F

Yes, you are correct but also note that for double and triple bonds they would also have pi bonds.

DominicMalilay 1F

Hybridization is usually for a specific atom, so you have to look at phosphorous first!

DominicMalilay 1F

It would be angular!

DominicMalilay 1F

In other words, it is pretty much like resonance!

DominicMalilay 1F

Yes, and the larger the atom the more polarizable because its electrons are further from the nucleus

DominicMalilay 1F

The expanded octet rule cannot be applied to period 2 elements as well!

DominicMalilay 1F

Yes because the dipoles cancel

DominicMalilay 1F

It can be any 2 electrons that repel each other!

DominicMalilay 1F

Quizlet is a life saver!

DominicMalilay 1F

That is the charge for the individual atoms if they were to lose or gain electrons. For the BH4- ion, if you draw the lewis structure and calculate formal charges, the total charge is -1.

DominicMalilay 1F

I think the general tip is that the more symmetrical the lewis structure is, it will probably be the lowest formal charge. Of course, you can check each structures' formal charges and the one with the most formal charges of 0 would be the lowest.

DominicMalilay 1F

BaBr2 is more ionic because the difference in electronegativity is the greatest. Be is more electronegative than Ba so when bonded with Br it's less ionic. FOr example, F2 is covalent even though F is the most electronegative. It's about the difference in electronegativity, not the atoms that add up...

DominicMalilay 1F

The lewis structure should just be the same as the lewis structures for phosphate and clo3- with a hydrogen attached to the oxygen. This cancels the -1 formal charge for the oxygen so instead of po4(3-) it would be hpo4(2-) and hclo3 instead of clo3-.

DominicMalilay 1F

From end of mt1 to chemical bonding

DominicMalilay 1F

What exactly is a quantum state?

DominicMalilay 1F

that's a good visualizer, thanks!

DominicMalilay 1F

x-ray diffraction is used to determine the bond length.

DominicMalilay 1F

They are omitted because they are inert and don't need any more e-

DominicMalilay 1F

Sunday 11:59 pst

DominicMalilay 1F

No, you don't need to draw the bonds shorter or longer!

DominicMalilay 1F

I would assume a the more covalent the character, the smaller the ionization energy because it would be easier to remove an electron since the electron is further away from the nucleus.

DominicMalilay 1F

How do the water molecules interact with NaCl to dissociate them?

DominicMalilay 1F

Why do electrons have spin? Are we just supposed to take this as a truth because of experimental data, or is there deeper reasoning behind electrons having spin properties?

DominicMalilay 1F

I don't have a mnemonic device to memorize the EM spectrum, but I just remember counting even powers down from 10^-10 being x rays, 10^-8 UV, 10^-6 and 10^-4 infrared, and then 10^-2 microwaves. This is in meters.

DominicMalilay 1F

For the electron affinity of thulium given 1064 nm and an energy of .137 ev, I'm confused how to find the electron affinity in ev/atom. I know it has something to do with debroglies equation, but I cant find the right units to solve it. Thanks in advance!

DominicMalilay 1F

Id say its true because with the equation E(photon)-work function=Kinetic energy, the higher the frequency, the larger the energy of photon, so the larger the kinetic energy.

DominicMalilay 1F

The hydrogen atom has a radius of approximately 0.05 nm. Assume that we know the position of an electron to an accuracy of 1 % of the hydrogen radius, calculate the uncertainty in the speed of the electron using the Heisenberg uncertainty principle. Comment on your value obtained. I solved using the...

DominicMalilay 1F

It's still a bit unclear about the amount of material we are able to use for the midterm; I thought I heard he was going to provide a printout sheet for the formulas, but I have not gotten an email about this.

DominicMalilay 1F

I was confused initially, but remember to also square the values of the energy levels if you use the Rydberg equation.

DominicMalilay 1F

Solve this exercise without using a calculator. The reaction 6 ClO 2 (g) + 2 BrF 3 (l) → 6 ClO 2 F (s) + Br 2 (l) is carried out with 12 mol ClO 2 and 5 mol BrF 3 . (a) Identify the excess reactant. (b) Estimate how many moles of each product will be produced and how many moles of the excess reactan...

DominicMalilay 1F

When given problems like how to calculate the volume of solution to obtain mol of Na in Na2CO3, the molar bridge conversion is 1 mol Na2CO3/2 mol Na+, so you would divide by 2. However, in other problems like the number of moles of nitrogen atoms a plant can receive, the bridge conversion is 2 mol N...

DominicMalilay 1F

As a good baseline, whenever I run into problems involving the velocity/speed of something, I think of the De Broglie equation!

DominicMalilay 1F

Professor Lavelle said that the midterm material will cover all lectures until Wednesday week 3, and he also said that these include all sapling problems until Q19. However, all the problems from Sapling stated above are material we have not covered. Will we still be expected to know these?

DominicMalilay 1F

Out of all the orbital structures in the d orbital, this one is the only structure that has the -y value in it. I was wondering about the reason for this.

DominicMalilay 1F

The average speed of a diatomic fluorine molecule at 25 ∘C is 442.4 m⋅s−1 . What is the average wavelength of a fluorine molecule at this temperature? Assume that the molecule acts like a single particle. Having trouble finding the mass for the single fluorine molecule. If it is diatomic do I use do...

DominicMalilay 1F

Its a mix of watching all the lectures, notes, and reviewing some old chem material from high school for the fundamentals for me!

DominicMalilay 1F

I think a good way of thinking about the photons' intensity is that the frequency and the wavelength have to be in proportion to each other since they are equal to the speed of light. So if you increase the intensity, you are still not increasing the frequency so that electrons are ejected by the wa...

DominicMalilay 1F

I don't think the constant matter as much as just making sure you do not round your calculator when doing a problem, and just make sure to keep everything in the calculator until the final calculation where you can round the answer to the proper sig fig.

DominicMalilay 1F

I believe in Lavelle's lectures, he writes the excess energy as E(excess) and kinetic energy as EK, with the k being a subscript.

DominicMalilay 1F

Along with Briannes reply, Avogadro's constant is exactly that, a constant that does not have specific units in terms of atoms, photons, molecules, or any other unit for measurement. This means it can be applied in many situations either to cancel out some units or to convert moles into molecules.

DominicMalilay 1F

Yes, to add on to Margaret's point, the electrons' whereabouts can be thought of as in s,p,d, and f orbitals, but do not take this like they are in one spot in the orbital. Electrons are constantly moving around in their respective energy levels and Heisenberg's uncertainty principle complicates thi...

DominicMalilay 1F

I'm in the same situation, and yes you can access the textbook. It should be on the right-hand side when you open Sapling as an ebook. I had to make an account to use the textbook.

DominicMalilay 1F

During Lavelle's first lecture, he discusses how the Avogadro constant arose from the number of atoms in 12 grams of C-12. I was wondering why scientists chose C-12 element for using Avogadros number.

DominicMalilay 1F

I was wondering how to properly solve this question since they do not give any units to work with. "What is the change in energy associated per mole of photons?"

DominicMalilay 1F

I was wondering what the usual cutoff point for rounding up empirical formulas is. For example, if the final moles of a compound containing C,H, and O are 2.67,2.67, and 1 you would multiply by 3, but what about numbers like 2.85,2.85, and 1, or any other variant for that matter.

DominicMalilay 1F

I'm wondering for "A reaction was performed in which 0.60 mL of 2‑butanone was reacted with an excess of propyl magnesiumbromide to make 0.71 g of 3‑methyl‑3‑hexanol. Calculate the theoretical yield and percent yield for this reaction" if I would need to balance the given chemical equation...

DominicMalilay 1F

Hey Meredith,

If I remember correctly I needed to multiply my answer by a factor of 2 to get within the set range of numbers. Have a good day!

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