CHEMISTRY COMMUNITY

Priscilla Okaiteye

What unit is delta H supposed to be in?

Priscilla Okaiteye

What unit is delta H supposed to be in?

Priscilla Okaiteye

Most of them are given

Priscilla Okaiteye

Ecell in electrocytic cells can be pos or neg, but also I have noticed in the textbook that there are a couple of problems where Ecell was pos for Galvanic cells. Usually, the value is supposed to be pos for Galvanic.

Priscilla Okaiteye

For naming the molecularity of elementary steps I know we take the species # into consideration but do we also look at the catalyst? What else is considered?

Priscilla Okaiteye

Yes, it can be treated as an ideal gas.

Priscilla Okaiteye

For those types, the Eo are voltages of half reactions. Together they make the whole reaction so we can add them.

Priscilla Okaiteye

Oh, I get it now thanks, guys.

Priscilla Okaiteye

that would be m^-1t^-1

Priscilla Okaiteye

Do we need to worry about third order anything?

Priscilla Okaiteye

Get it... xD

Priscilla Okaiteye

Dear Dr. Lavelle, Thank you so much for a great quarter. I honestly don't know how far I could have gotten without that UA session. You are one of the very few professors that actually care how students do in the class and what they understand. I learned a great deal from you and hope continue to co...

Priscilla Okaiteye

Could anyone please give an example of that I am also kind of confused.

Priscilla Okaiteye

Does anyone have any quick or easy ways to remember rules and equations for the final?
i.e: mnemonics

Priscilla Okaiteye

Yes, along with the periodic table they have to.

Priscilla Okaiteye

You reverse one of the equation, preferably the one with a smaller value so that you can cancel out the electron charges and other species that appear on both sides, but for this question, I think they chose the second reaction because they wanted Ag+ and Cl- to be on the products side. I'm not enti...

Priscilla Okaiteye

Pick up line joke:

You must be a compound of Barium and Beryllium because you are a
BaBe.

Priscilla Okaiteye

I thought this was kind of cute when I saw it...

Priscilla Okaiteye

For questions like finding the order of the reactant when you are given trials, I know the rule is to use two trials that keep the other reactants constant and have the reactant you are focusing on changing, but how come in som e questions that is not the case? For example in 15.17 part a). The solu...

Priscilla Okaiteye

For integrated rate laws of the first order are there any keywords that can help determine which type of the equations to use in questions?

Priscilla Okaiteye

How would questions for the reaction mechanism be asked? What does that mean? What process do we have to go through? I guess what I'm really asking is how would it be asked on the final?

Priscilla Okaiteye

>Your cathode goes on the right and your anode on the left. >two lines stand for a salt bridge >one line represents interference between phases in contact and you can also use it for adding the conductor(i.e platinum >and always put the new notation near the salt bridge That's about all I know

Priscilla Okaiteye

Do we also have to know or study the graphs for half-life?

Priscilla Okaiteye

A substance A decomposes in a first order reaction and its half-life is 355s. How much time must elapse for the concentration of A to decrease to :
a) 1/8[A]o

How would I go about starting to solve this question? Would I just use the first order half life equation?

Priscilla Okaiteye

In the lecture, Friday Lavelle was talking about zero order rate reactions and its molecularity. I didn't quite catch what he was saying. Could someone please explain.

Priscilla Okaiteye

The cell stops working after a period of time because the reaction has stopped. That means that the reactants have all transformed.

Priscilla Okaiteye

Can we still do homework on thermochemistry or is it just thermodynamics now?

Priscilla Okaiteye

In Friday's lecture when the professor was talking about method 2 (using bond enthalpies to calculate the change in the H reaction) I did not quite catch what he was saying when he was going over the example. What did he mean when he was talking about the carbon double bond? What happen to it?

Priscilla Okaiteye

Does anyone know a quick way to tell if a chemical is an acid or base without being given the formula?

Priscilla Okaiteye

When we are writing out the concentrations to find the k constant if not all the products and reactants are gases, do we still use the P notation?

Priscilla Okaiteye

Are we allowed to do the homework questions that were used in discussion?

Priscilla Okaiteye

Hi. I am still having trouble with Pi bonds and sigma bonds how do you draw them out on your own, how do you recognize which is which. Does anyone have a video or resource they use to understand this?

Priscilla Okaiteye

It applies to covalent bonds. Since the Ionic bond is really one atom stealing from another it does not really apply. Polarity has to do with there being an unequal sharing of electrons. There is a stronger pull from one of the atoms.

Priscilla Okaiteye

One compound is more likely to give away that H+ than the other. CH3OOH has its hydrogens delocalized more so it's easier for them to leave making it the better acid.

Priscilla Okaiteye

Metal Oxides react with water to form a strong base, and nonmetal oxides react with water to form strong acids.

Priscilla Okaiteye

For acidic oxides, they react with water to form a Bronsted acid, basic oxides will form a hydroxide when reacting with water, and amphoteric substances are just thing that has both acidic and basic character, like H2O.

These are just ways you can identify them, but I'm pretty sure there are more.

Priscilla Okaiteye

Yes. Yes, it is.

Priscilla Okaiteye

...and maybe also show an example?

Priscilla Okaiteye

Can someone just briefly explain to me what the coordination number is and how to find it?

Priscilla Okaiteye

Also, NH3 is a base because the Nitrogen atom in it contains a lone pair which can donate its electrons to other atoms, therefore, it can be considered as a base. Or you can think of it as it can accept a proton.

Priscilla Okaiteye

Hi. Just a quick question. Can someone please clarify the relationship between something being polar and something being soluble?

Priscilla Okaiteye

Hi everyone, I just wanted a little clarification on what exactly covalent character would be. Is it used to describe ionic bonds right?

Priscilla Okaiteye

I know this was answered in class but I did not really understand what was being said. What is the relation between ph and pKa and pKb? How do find them using the other?

Priscilla Okaiteye

Hi, This has to do with how easily the electrons can be taken away from an atoms electron cloud. The bigger the atomic radius, the higher the electron distortion, and therefore the higher polarizability. Since their electron cloud is so big they are farther away from the nucleus and can be affected ...

Priscilla Okaiteye

How is it that a molecule can have dipole moments in its bonds, and then nit be polar?

Priscilla Okaiteye

Okay, so Helium only has 2 electrons which means it doesn't need 8 or an octet. It is a noble gas. All its shells are filled. Now Lithium and beryllium are sort of the same in the sense that they don't need 8 electrons. They do give away valence electrons to have their next shell filled.

Priscilla Okaiteye

The textbook is just talking about cations and anions made up of one atom. For example, Na+ is a monoatomic cation and Cl- is a monoatomic anion, because there is only one atom here. When we have covalent bonds acting as one they are polyatomic, more than one ion. They can be ions as well.

Priscilla Okaiteye

I'm not sure about your second question but yes the electrons can get excited and move orbitals. Just think of atoms with an excited state and a ground state.

Priscilla Okaiteye

I don't quite get how hybrid orbitals are formed. How do the s and p orbitals become hybridized?

Priscilla Okaiteye

The 4d orbital is at a much higher energy level than 4s or 4p. The 3d orbital has a very close energy level to 4s and will alternate depending on its electron state. Just know that it is not 4d because it would not make sense to write 4d before 4s. It just all because of the d orbital's energy level.

Priscilla Okaiteye

For subshells with more than one orbital we fill each on with one electron before coming back to add the second electron. This all the single electrons in the subshell will be rotating in the same direction making them parallel. When you add the second electron to the subshells the mush rotate in op...

Priscilla Okaiteye

The formula for questions that don't use hydrogen is a little different, but I do not think we have to worry about it since the professor hasn't discussed it.

Priscilla Okaiteye

Priscilla Okaiteye

Depending on the type of question this could be very simple. If you are given enough information in the question just use the formula E=hv. That would be the energy of the photon is equal to the frequency times Plank's constant.

Priscilla Okaiteye

I do not quite understand the purpose of the work function. Can someone please explain it to me? When would you use it? What type of questions would require you to use the work function?

Priscilla Okaiteye

You would have to see the number of significant figures in the log(excluding whats beyond the 10^x) and in your answer, that's the number of sig figs to the right of your decimal.

Priscilla Okaiteye

For the problem: how would you prep a 10mL of ).015M KOH solution starting from solid KOH?
would I have to find the molar mass to answer this question or is it straightforward?

Priscilla Okaiteye

A 0.2500g sample of a compound known to contain carbon, hydrogen, and oxygen undergoes complete combustion to produce 0.3664g of CO2 and 0.1500g of H2O. What is the empirical formula of this compound? The molar mass of hydrocarbon is 180.16g/mol, what is the molecular formula?

Priscilla Okaiteye

It would remain the same. The empirical formula is the formula of the chemical equation with the lowest ratio or the most simplified version of the formula. It would not be H5NO because that is a whole different formula.

Priscilla Okaiteye

I just need help on this question for practice: A photon generated as a result of which of the following transitions in the hydrogen atom will have the greatest energy? Explain your answer. (a) From n = 6 to n = 5; (b) From n =4 to n = 3; (c) From n=2 to n = 1.

Priscilla Okaiteye

I know this was covered in lecture but I'm still a bit confused. What exactly is the threshold energy and how does it relate to quantum equations?

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