CHEMISTRY COMMUNITY

MichelleRamirez_2F

Bimolecular means that for a certain reaction there are two reactants. There's also unimolecular where there is only 1 reactant in the reaction and termolecular for three reactants.

MichelleRamirez_2F

The textbook says their are mostly uncommon. It may be useful to know because they may appear when asked for overall reaction order.

MichelleRamirez_2F

For Q7, how come we don't the number of electrons for the half reactions given when adding them to get the overall reaction?

MichelleRamirez_2F

Yes, endergonic is deltaG>0 and exergonic is deltaG<0.

MichelleRamirez_2F

k' is referring to the reverse reaction.

MichelleRamirez_2F

It has to do with the temperature. SInce we are increasing the temperature, and the reaction in endothermic this will accelerate the reaction meaning more product will form, so the equilibrium would shift to the right.

MichelleRamirez_2F

This is the link to the midterm solutions: https://lavelle.chem.ucla.edu/wp-conten ... am_ans.pdf

MichelleRamirez_2F

In lecture professor Lavelle mentioned that we only need to focus on the Pre-Equilibrium approach.

MichelleRamirez_2F

I know that in the 14B website there is a link to the equation list we are given for the test.

MichelleRamirez_2F

Bar is the proper unit for partial pressure for equilibrium constant calculations.

MichelleRamirez_2F

I think they did mention we would be given a sheet like the one for test 2.

MichelleRamirez_2F

I don't think they post the solutions for the tests because there is usually a review session by a TA where they go over the solutions.

MichelleRamirez_2F

The problem would state whether it is in a basic or acidic solution.

MichelleRamirez_2F

What is k' and when are we supposed to use it?

MichelleRamirez_2F

Help with the question: rank in order of increasing oxidation power going from their second oxidation state to neutral: Ti2+, Sn2+, Mg2+.
What lets us know their rank?

MichelleRamirez_2F

Can someone help with this question from test 2.
Rank the following species in order of increasing reducing power going from their neutral to second oxidation state: Pt, Pb, Cu.
How do we know this?

MichelleRamirez_2F

I believe it is when it's at equilibrium.

MichelleRamirez_2F

If you are talking about a first order reaction the doubling of a reactant means the reaction rate is doubled. If it's a second order reaction then the reaction rate is increase by a factor of x^2, where x would be your reaction rate.

MichelleRamirez_2F

For a second order reaction k is Lx mol^-1x s^-1.

MichelleRamirez_2F

In the textbook it is mentioned how the reaction order can be a negative number=negative order . This would signify that the concentration value of the species is in the denominator of the rate law. The species in this case is usually a product and it represents the reverse reaction.

MichelleRamirez_2F

What are the units for a zero order reaction, if any?

MichelleRamirez_2F

What is the difference between a reducing agent and a reduced species? And an oxidizing agent vs a oxidized species?

MichelleRamirez_2F

Since that was part of the last lecture covering the topics of test 2 I would assume we do need to know it.

MichelleRamirez_2F

Does the value of the cell potential/E change if the value of your stoichiometric coefficient of one reactant changes?

MichelleRamirez_2F

What is the diffrenece between Ecell and E^o cell?

MichelleRamirez_2F

In the sixth edition textbook the example problem for specific heat and molar heat states that the temperature changes from 20C to 100C. In their work however they treated the deltaT as 80.K. My question is why they didn't convert 80C to 353K?

MichelleRamirez_2F

If you are given moles then use n and molar heat capacity, nad if you are given mass (g) then use m and specific heat capacity of the substance.

MichelleRamirez_2F

I would say that it is only focused on the topics covered in class and if you are using the textbook to only focus on the section of the chapters that come before the Gibbs Free energy section. In the case of the 6th edition it would be to only go up to section 9.11 from Chapter 9.

MichelleRamirez_2F

In the examples we have done in class we have added 273K.

MichelleRamirez_2F

Usually the problem you are solving will tell you which one to solve for. In some occasions you may have to solve for both for the same problem.

MichelleRamirez_2F

I don't think that lone pairs affect the polarity of an atom. Instead its electronegativity and the atomic radius would affect how likely it would be able for its electron cloud to be distorted.

MichelleRamirez_2F

You have to see what the charge would be on the compound to figure out how many potassium molecules would neitralize that charge.

MichelleRamirez_2F

Following the answer above, the nitrogen would make the thymine the base because it has a lone pair electrons.

MichelleRamirez_2F

It depends on the reaction because water is considered to be amphoteric meaning it can be an acid or base.

MichelleRamirez_2F

NH3 would have a higher boiling point because the nitrogen forms bonds with H. Remember that for intermolecular forces it goes from Van der Waals, dipole-dipole to H-binding as the strongest.

MichelleRamirez_2F

H2O is amphoteric because it can be an acid or base. This means is can either accept an electron or donate an electron.

MichelleRamirez_2F

Boiling point from least to greatest is Van der Walls, dipole-dipole and H-bonds.What helps determine boiling point can also be the size of the molecule because the bigger the molecule, the more London forces which also leads to a higher boiling point.

MichelleRamirez_2F

All topics will be covered in the syllabus, so you should be able to understand quantum as equally as the other topics.

MichelleRamirez_2F

Amphiprotic is when the compound can either donate or accept a hydrogen.

MichelleRamirez_2F

Can someone explain why hemogrlobin is tetradentrate but cisplatin is monodentrate?

MichelleRamirez_2F

I think that a chelate is when the ring structured compound binds a central metal at two or more places.

MichelleRamirez_2F

When we are loking for pH why is pH= log10[H30]? How do we know what the value of [H3O] is?

MichelleRamirez_2F

When given a chemical formula how do we know which one is the cetral metal atom or ion?

MichelleRamirez_2F

So to make sure we have the correct Lewis structure we calculate the formal charge of the possible structures we have drawn?

MichelleRamirez_2F

Lone pairs affect the structure of the VSEPR model beacues they have the highest repulsion so they try to be fathest apart from each other. Also they cause repulsion with the other atoms bonded with the central atom which is why the angles of some shapes turn out to be slightly smaller than the orig...

MichelleRamirez_2F

Arlene Linares 3A wrote:Can someone explain lone pairs to me?

Lone pairs are the pair of electrons that do not get shared with another atom in the molecule.

MichelleRamirez_2F

I think you are only allowed to write the tests in pen. Atleast for the midterm they mentioned that only what was written in pen would be graded. This seems reasonable to since we receive our tests back after they are graded and things written in pencil can easily be erased.

MichelleRamirez_2F

How do you know when. you need to form a double bond or if the bond between the atoms must stay as single bonds?

MichelleRamirez_2F

You would still have to draw the Lewis structure ( with help of the hybridization) to see whether the bonds are single, double and triple bonds. Once you know the structure the number of sigma bonds are the number of. single bonds and the pi bonds are any bonds starting from the second bond. This me...

MichelleRamirez_2F

When we are considering the bond angles, for molecules with lone pairs do we consider the bond lengths of the electron arrangement or of the molecular shape?

MichelleRamirez_2F

Electronegativity decreases down a group since Cl is lower than O, I want to.say that O is more electronegative than Cl.

MichelleRamirez_2F

The lone pair is placed on the axis of the molecule. This is the Axail lone pair and it is placed in this position because of the repulsion of the atoms from the electron pair.

MichelleRamirez_2F

When we are trying to answer whether a molecule is polar or non polar how do we determine the direction of the bond?

MichelleRamirez_2F

The atomic radii helps you understand why the polarizing power increases or decreases since the size of the radius correlates with how much power the nucleus has on the valence electrons.

MichelleRamirez_2F

For VSEPR since the central atom is the "important atom" we only focus on the shared electron it has with the other atoms. Because of this it is not necessary to dram the valence electrons of the other atoms.

MichelleRamirez_2F

How do we know when the Ms quantum number should be -1/2, or 1/2?

MichelleRamirez_2F

What is the difference between principal quantum number and magnetic quantum number?

MichelleRamirez_2F

You should convert the given values to the required SI units before plugging them into the equation you are using (like e=hv etc) that way when you are solving the problem you are able to "cross out" the units that you don't need in your final answer. At the end, if they are asking for a c...

MichelleRamirez_2F

The front page of every exam should gave the general equations and constants that you will need.

MichelleRamirez_2F

You may also want to refer to Dr. Lavelle's "Math Assistance" section where he has two documents that goes over the use of significant figures thoroughly!

MichelleRamirez_2F

When you are multiplying you must use the smallest number of significant figures in your data to be the number of significant figures in your answer. For example, if you are multiplying 6.18165 x 3.56=22.0 your answer must only have 3 significant figures since that is the smallest number of signific...

MichelleRamirez_2F

The net number of molecules would be the difference between the number of moles produced minus the number of moles you began with. You will know the number of moles of your reactants and products by adding the given coefficients in front of their respective molecules form the reaction. (Make sure yo...

MichelleRamirez_2F

Raquel Rodriguez wrote:Do you guys know when our first test is?

It would be during your discussion section in week 2.

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