CHEMISTRY COMMUNITY

Adrienne_4F

Can someone explain what they did for this problem? I tried to find e^-Ea/RT for each of the activation energies given and compare them but that wasn't the right thing.

Adrienne_4F

In the solution manual is says that we expect the forward reaction to go up more than the reverse. How do we know this is true?

Adrienne_4F

Yes it is inverse. It would be 1 over K of the forward reaction.

Adrienne_4F

Can someone explain this in terms of oxidizing power and how that differs?

Adrienne_4F

The overall order can help us determine the units of K and figure out which order reaction equation we should use.

Adrienne_4F

I don't think there's necessarily a way to prove that a mechanism is correct but it can be proved incorrect if the mechanisms do not fit the experimental data.

Adrienne_4F

He will probably make a post on chemistry community so just keep an eye out for it!

Adrienne_4F

Rate is moles per liter per second

Adrienne_4F

A catalyst is always present as a reactant first, but an intermediate comes up as product first.

Adrienne_4F

In the example he gave in class about the conversion of oxygen to ozone in lower atmosphere using NO(g), would both NO2 and O be an intermediate and NO is the catalyst?

Adrienne_4F

Hello, if anyone has the answers for Lyndon's review session from week 8 on electrochemistry, please share. It was very full and I couldn't see or hear anything. Thank you. It is greatly appreciated :)

Adrienne_4F

In our notes when we're finding E cell, why is the answer .43V even though we have cathode as .77V and anode as -.34 V? shouldn't it be .77-(-.34)=?

Adrienne_4F

Why does A, the monatomic gas have a larger enthalpy change than a diatomic gas?

Adrienne_4F

For change in entropy for change in temperature, why does it use R when the equation for delta S change in temp is delta S=nClnT2/T1?

Adrienne_4F

What other molecules besides O2 and N2 have o enthalpy of formation?

Adrienne_4F

How do we know that the delta H given is KJ/ mol? Is it always assumed that it's KJ/mol?

Adrienne_4F

In the book, it talks about how a gas might push a piston into a vacuum in which no work is being doing. What does it mean by pushing into a vacuum?

Adrienne_4F

Hi, it might be helpful to look at question 8.1. They ask you to identify which systems are open, closed, or isolated.

Adrienne_4F

Why is PdeltaV insignificant if it involves liquids and solids?

Adrienne_4F

What does it mean by U is a state property?

Adrienne_4F

How does positional (residual) entropy differ from normal entropy?

Adrienne_4F

In our lecture notes, what does it mean by "molecules in gaseous phase occupy many more states than liquid and solid?"

Adrienne_4F

In melting and boiling, why does the temperature of a sample stay constant even though heat is being added?

Adrienne_4F

What does it mean by enthalpy is a state function ?

Adrienne_4F

Products will always be plus if you start out with no products. If the reaction is going forward, then products will be plus but if the reaction is going backwards, the reactants will be plus.

Adrienne_4F

When you have an acid reacting with water, you'll result in H3O+ because the atom donates an H to water. With bases, you'll get OH- because that atom will take an H from water.

Adrienne_4F

What other examples of autoprotolysis are there besides the example with water? What aspects of autoprotolysis do we need to know for Test 1?

Adrienne_4F

How do we know that the coefficient for A and C is 2 based on the graph that is given?

Adrienne_4F

Can pressure be changed without changing the volume? If yes, how?

Adrienne_4F

If water is in gas form, will it be included in the equilibrium equation?

Adrienne_4F

What is the difference between Keq, Kc, and Kp? Does it matter if we use Keq for Kp since Keq is the general equilibrium constant?

Adrienne_4F

What does R represent in PV=nRT?

Adrienne_4F

If a compound is amphoteric, is it also amphiprotic?

Adrienne_4F

Why does a strong acid have a smaller pH compared to a weak acid that has a higher pH?

Adrienne_4F

What's the difference between a Lewis and Bronsted Acid and Base?

Adrienne_4F

Some of the names of molecules have roman numerals. How do we know which ones have roman numerals and what the roman numerals are?

Adrienne_4F

Can someone explain exactly what heme structures are or what heme means? Thank you

Adrienne_4F

I assume you have to know the ones that come up in examples a lot, like hydroxide, ammonia, oxide, etc.

Adrienne_4F

Hi! I really enjoy going to Lyndon's workshops. He's super helpful and makes things very easy to understand. 10/10 would recommend :)

Adrienne_4F

How do we explain pi bonds using hybridization? There was an example from class for C2H4, but I don't understand it.

Adrienne_4F

There is repulsion due to the two lone pairs, therefore they will push the atoms closer together, making a T shape rather than a trigonal planar.

Adrienne_4F

In question 4.29, why does 1 have the largest dipole moment although the distance between the two chlorines is the smallest?

Adrienne_4F

What exactly does the dipole moment tell us and how do we determine whether a dipole moment is large or small?

Adrienne_4F

In our notes, professor wrote the hybridization as 2sp, 2sp2, etc but in the the textbook they write it just as sp, sp2, etc.. what is the difference?

Adrienne_4F

Yes, all molecules have this bond. In our notes, it states that all dispersion interactions are always present and active and Van der Waals is just another name for dispersion.

Adrienne_4F

How can we differentiate between a polar and nonpolar molecule?

Adrienne_4F

Like others have said, its the average of the lengths. so if you had 2 single bonds and one double bond, you would add all three and divide by 3.

Adrienne_4F

In our notes from October 31st, we drew boron trifluoride, but boron only has 6 electrons, why? Don't all elements need 8 electrons?

Adrienne_4F

Can someone explain why some of these atoms have octet exceptions? what makes them different from others?

Adrienne_4F

Can someone explain electron affinity and how it applies to the periodic table?

Adrienne_4F

If there are any black body radiation questions, what might we need to know? Any ideas?

Adrienne_4F

What kind of general concepts should we understand in terms of shrodinger's equation? Are there any good examples in the textbook that might be useful?

Adrienne_4F

Removing the second electron is more difficult because the atom pulls on the second electron stronger. In the example he gave us, after removing one electron from copper, it became Cu+, therefore the nuclear charge is stronger than Cu.

Adrienne_4F

Will we need to know the drawings for f- orbital?

Adrienne_4F

Why is copper [Ar] 3d^10 4s^1, not [Ar] 3d^9 4s^2? Same for chromium which is [Ar] 3d^5 4s^1, not [Ar] 3d^4 4s^2? I remember he mentioned it's so that the element is more stable. What does that mean?

Adrienne_4F

I'm very confused. What does the equation actually help us find? Also, what do orbitals have to do with the equation?

Adrienne_4F

Why is delta E negative when we go from the fourth to the second principal quantum level?

Adrienne_4F

When we're using Planck's constant, do we use 6.626 X 10^-34 or 6.63 X 10^-34? Professor switches off between the two in the lecture notes.

Adrienne_4F

Can someone explain what threshold energy is and how it is relevant to today's lecture? Thank you.

Adrienne_4F

E is the energy of the particle or photon, with the units joules.
H is just Planck's constant, which is 6.63 X 10^-34 joules X second.
V is the frequency, with the units Hertz or S^-1.

Energy and frequency are directly proportional, therefore when frequency increases, energy increases.

Adrienne_4F

Hi, I'm a little confused. When Professor Lavelle explained higher energy in the lecture he did not mean higher intensity correct? A higher intensity would generate more protons but not stronger protons. A higher energy would generate stronger protons. Is my understanding correct or? Also what is th...

Adrienne_4F

How do we know what order to write the empirical or molecular formula in?
For example, F17. In the solution manual they wrote Os before C and H. How would we know that?

Adrienne_4F

When we're using the molar mass, should we estimate according to how many sig figs are in the problem or do we use the most accurate molar mass we have?

Ex. problem asks to gives 3.45 g. of carbon. Would we use 12.0 or 12.011 for the molar mass?

Adrienne_4F

Hi! I'm a little confused about the SI unit for mass. In the lecture, professor said that the SI unit for mass was kilograms. When we're writing our answers, do we convert our answers from grams to kilograms? Thank you!

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