CHEMISTRY COMMUNITY

Daniel Lai

Concentration cells have the same element on both sides just with different concentrations so there is not Ecell for standard conditions.

Daniel Lai

The outline says to be familiar with industrial and biological examples so I'd just study it.

Daniel Lai

When they say "of NH3," they mean one NH3.

Daniel Lai

Yes. You are correct.

Daniel Lai

A higher concentration of cations means electrons are more drawn to that side.

Daniel Lai

Use the equation for the difference in temperature for Arrhenius equations.

Daniel Lai

It depends if it is a pH = 7. They give it to you before the questions.

Daniel Lai

They will always be separated because solids can't mix.

Daniel Lai

You can use Nernst Equation to find Q or K if it is at equilibrium. Then you can solve for [H+] if you are given other concentrations.

Daniel Lai

DeltaH = q at constant pressure. DeltaH doesn't correlate with w ever.

Daniel Lai

Indeed. You are correct.

Daniel Lai

We don't have to know that. We have to pre-equilibrium only.

Daniel Lai

Gibbs free energy of formation is 0 for elements in their standard states.

Daniel Lai

The units of the rate are always the same, mol/(L*s). k has the same units. because concentration doesn't matter. Half life is always in time units.

Daniel Lai

No, we do not.

Daniel Lai

I believe it is only a single new mechanism because we are dealing with mechanisms of the whole reactions, not individual subreactions.

Daniel Lai

You are correct. Well done.

Daniel Lai

You take the difference of two Arrhenius equations. It's in the book.

Daniel Lai

I think the solution manual is wrong. The value you get should be lnK2/K1 = -0.59. And then you solve.

Daniel Lai

If it is a straight line on the graph, then it is linear.

Daniel Lai

That particular equation won't be given. The derivation is just taking the difference of two Arrhenius equations.

Daniel Lai

For zero order, its A. For first order, its lnA. For second order, its 1/A

Daniel Lai

A student was given a standard Cu(s)|Cu2+(aq) half-cell and another half-cell containing an unknown metal M in 1.00 M M(NO3)2 (aq) and formed the cell M(s)|M+||Cu2+(aq)|Cu(s). The cell potential was found to be -0.689 V. What is the value of E(M2+/M)? I don't understand how we're supposed to know wh...

Daniel Lai

It sorta depends on how the rest of the class does. This class isn't curved but the grades are scaled. So, Lavelle will select a grade he thinks a B should be and then base everything around that score.

Daniel Lai

Negative delta G is spontaneous and positive is not spontaneous

Daniel Lai

It means work is being done on the system.

Daniel Lai

The midterm covers till right before Gibbs Free Energy.

Daniel Lai

I think it depends on what they are asking for. If they do not specify, just make sure its clear which one you are finding.

Daniel Lai

Autoprotolysis is when water ionizes itself by donating a proton to another water molecule, but the liquid water remains neutral. This helps us derive the equation [H3O+][OH-] = Kw which is helpful in acid base calculations.

Daniel Lai

I don't think you need to convert to concentrations because the answers seem to be in bars. You can just carry out the calculations in terms of pressure and Kp.

Daniel Lai

Aqueous solutions are included in the calculation because compounds dissociate in solution.

Daniel Lai

How do I know if something is a strong base?

Daniel Lai

In the books section on ionic radius Li+ is bigger than Mg2+.

Daniel Lai

Yea, but i thought we use ionic radius because these are ions?

Daniel Lai

Why is the polarizing power from least to greatest Na+, Mg2+, Li+, Be2+? I get why Na+ is the least and Be2+ is the greatest but I do not get why Li+ would be greater than Mg2+. Li+ is larger than Mg2+ according to the diagram of ionic radii in 1F.3 7th Edition and it has a lesser charge, so wouldn'...

Daniel Lai

I think greater polarity in the bond means they are more likely to dissociate.

Daniel Lai

They mainly affect the shape since lone pairs do not have polar properties.

Daniel Lai

I think we need to know C2H8O2.

Daniel Lai

I think either should be fine. I normally use -o because they use that in the answer key more.

Daniel Lai

Tetrahedral is indeed always sp3.

Daniel Lai

It depends. Different numbers of lone pairs can change the hybridization of the central atom but not change the shape. For example, a linear geometry can have 0 or 3 lone pairs.

Daniel Lai

Lone pairs count as an area of electron density so they count for hybridization.

Daniel Lai

Basically. you have to draw a lewis structure first that fits the molecule. Then, see if it has resonance. It's difficult to just tell off the bat unless you have a lot of practice.

Daniel Lai

If they are opposite each other or have the same relative force of attraction, then they cancel out.

Daniel Lai

I do not think you have to unless it asks for it or all resonance structures.

Daniel Lai

Square planar has two lone pairs that cause the 4 atoms surrounding the central atom to form a square. Tetrahedral has no lone pairs .

Daniel Lai

Polarity does not affect it, only having the formal charges closest to 0 matters.

Daniel Lai

Yes, I think so, because tetrahedral geometry has 4 areas of electron density.

Daniel Lai

If the formal charges are close to 0, then you use that one.

Daniel Lai

When there is an odd number of valence electrons, it will be a radical formation.

Daniel Lai

Yes, if you want to find the most stable form.

Daniel Lai

The number of dots is the number of electrons for that element.

Daniel Lai

Ozone is a good example for resonance. The double bond can be on either side of the central oxygen, so there are two resonance structures.

Daniel Lai

Most elements try to go for a full octet or a half-filled octet.

Daniel Lai

The 4s orbital is only less in energy when there are no electrons in 3d. But, once 4s and 3d are filled, 4s is higher in energy, so it is the first to lose electrons.

Daniel Lai

I think your answer is right. We went over this question in my discussion and we got 1.08*10^10 1/s.

Daniel Lai

I would not think so since nothing like that was covered in class.

Daniel Lai

I think the one line represents the particular wavelength of light.

Daniel Lai

We don't need to know electron configuration or periodic trends.

Daniel Lai

Don't worry about Black Body Radiation. It's not required knowledge for this class.

Daniel Lai

This question was really hard. I looked at the books method, and it didn't make any sense. I did it a different way by determining the coefficients of the other terms using empirical method. Did anyone else do it this way???

Daniel Lai

I think it's negative because we are viewing the energy relative to the electron. So, the electron is losing energy, thus the change in energy is negative.

Daniel Lai

I agree.

Daniel Lai

Basically, zeroes before the decimal point with the decimal point behind them and zeroes following the decimal point are significant. The only zeroes that aren't significant are zeroes in a number like 120 where they are no decimal points.

Daniel Lai

Generally, I start by finding the compounds with single atoms in its formula. So, for example, if I see C6H8O6 on one side and I see CO2 on the other, I'll start by putting a 6 in front of the CO2.

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