CHEMISTRY COMMUNITY

Josephine Lu 4L

is the overall order of a reaction the same as its molecularity?

Josephine Lu 4L

will we get docked off points if we have incorrect sig figs on the final? On the midterm, sigs figs were not heavily looked at, so is it the same way for the final?

Josephine Lu 4L

when writing rate laws, is writing them equal to "rate" or "d[A]/dt" the same? (assuming A is a concentration).

Josephine Lu 4L

in writing rate constants, do we write "k1 prime" or "k-1"? I've seen both be used in various hw problems, so are they interchangeable?

Josephine Lu 4L

when we write the rate laws, do we write it as "rate=..." or ""d[A]/dt=..."? Specifically in question #3 of the Reaction Mechanisms worksheet, could we replace "d[F]/dt" with "rate"?

Josephine Lu 4L

why does the slow step not influence the overall rate?

Josephine Lu 4L

In question 15.17 of the hw, the solutions say that c is independent of the rate, thus it does not appear in the rate law. How do we determine this from the experiment data?

Josephine Lu 4L

in this question of the 6th edition textbook, how do we know that both half reactions proceed towards Au(s)?

Josephine Lu 4L

could someone please explain #8 part a on the electrochemistry worksheet? How do we know that S2O8 2- is reduced and NO is oxidized?

Josephine Lu 4L

What is the difference between positional disorder and thermal disorder? In homework question 9.85, why is positional disorder dominant?

Josephine Lu 4L

If delta S of the reaction is positive, why will the reaction be spontaneous?

Josephine Lu 4L

Why are compounds with a positive free energy of formation (delta G) unstable?

Josephine Lu 4L

what does the Cv mean in the equation deltaS=nCvln(t2/t1) ? what does it stand for, and when should i use it as opposed to deltaS=nRln(V2/v1)?

Josephine Lu 4L

What does the kB in the equation deltaS=kB lnW mean? Is it a constant that we memorize? If it is, will it be given in the constants and equations sheet on the midterm?

Josephine Lu 4L

In what circumstances should I use the equation of change in entropy deltaS=q/t versus deltaS=nRlnV2/V1? I don’t know when I should use which equation.

Josephine Lu 4L

When should I use R=8.314 versus using R= 8.206 * 10^-2 ?

Josephine Lu 4L

Why is q=deltaH under constant pressure? What is the reasoning behind it?

Josephine Lu 4L

In this homework question, how do we know that the temperature is at 298K? It does not explicitly mention the temperature in the question, so how are we supposed to know that?

Josephine Lu 4L

Why does Hess's law depend on the fact that enthalpy is a state property?

Josephine Lu 4L

Will we be required to derive the work equation (-P*deltaV) for the midterm?

Josephine Lu 4L

Internal energy is a state property. It is found by adding q (heat) and w (work).

Josephine Lu 4L

Will autoprotolysis of water be tested on Test 1? If so, is solving for (using ICE boxes) autoprotolysis equations the same as for regular neutralization equations?

Josephine Lu 4L

Why is it that when we increase pressure, the reaction favors the side with less moles of gas?

Josephine Lu 4L

the coefficient in front of the molecule is multiplied to x when you fill out the change values in the ICE box. For example, if a molecule has the coefficient 2, it would change by +/- 2x.

Josephine Lu 4L

In 12.81, the answer says that since Ka2 << Ka1, the second ionization can be ignored. What is the criteria to knowing when the second ionization is very small?

Josephine Lu 4L

if Kc<10^-3, then you can use the approximation and ignore x in the denominator

Josephine Lu 4L

On number 11.69, the question asks: Consider the equilibrium CO + H20 >> CO2 +H2. If the partial pressure of CO2 is increased, what happens to the partial pressure of H2? The answer says that increasing the partial pressure of CO2 will create more reactants, thus decreasing the partial pressure of H...

Josephine Lu 4L

The partial pressure equation is used to convert a gas from units of atm or bar to moles per liter. It is useful when we have a Kc value instead of Keq.

Josephine Lu 4L

I think that this would mean no dynamic equilibrium would be happening inside humans, as in no cellular processes would be occurring, because reactants have ceased becoming products and vice versa.

Josephine Lu 4L

In question 11.13 in the textbook, it asks to find the reaction quotient. Is reaction quotient the same as equilibrium constant?

Josephine Lu 4L

When we name a coordination complex with a charge (positive or negative), do we need to add the word "ion" at the end?

Josephine Lu 4L

When would you use the prefix "mono" when naming coordination compounds?

Josephine Lu 4L

What is an example of a molecule that is amphoteric but not amphiprotic, and what makes it that way?

Josephine Lu 4L

Are strong acids and strong bases always completely ionized in water?

Josephine Lu 4L

I believe we add "o" to the end of an anion. Cyanide is an anion, so it is named as cyano.

Josephine Lu 4L

can a molecule be a bronsted acid and a lewis acid at the same time?

Josephine Lu 4L

why does an electron prefer to occupy an unhybridized orbital before spin pairing in a hybridized orbital?

Josephine Lu 4L

Why is it that sigma bonds allow rotation, while pi bonds do not?

Josephine Lu 4L

What is the difference between a cis and trans molecule?

Josephine Lu 4L

Hello Karen! If you went over any notes (wrote stuff on the board) on Sunday, could you please send those notes? Thank you so much!

Josephine Lu 4L

what does it mean when a lone pair is in the axial or equitorial plane?

Josephine Lu 4L

what is the difference between a sigma and pi bond?

Josephine Lu 4L

Intramolecular forces are stronger than intermolecular forces, because the attractions that hold compounds together are stronger than the attractions between molecules.

Josephine Lu 4L

An octahedral vsepr shape can be visualized as two square pyramids with their bases pressed together to form a sort of diamond shape with 8 sides.

Josephine Lu 4L

Delocalized electrons are electrons that are involved in resonance structures. For example, benzene, C6H6, has three delocalized double bonds, meaning that the three double bonds can be placed in different areas.

Josephine Lu 4L

You would need to draw all the possible resonance structures, because resonance is a blend of structures with the same arrangement atoms, but just with different arrangements of electrons.

Josephine Lu 4L

Hi Karen! Will you still be holding a workshop this Sunday (over Veteran's Day weekend)?

Josephine Lu 4L

My TA told me that we would not need to name ionic compounds, that they would be given on the exam.

Josephine Lu 4L

Electron affinity is the energy that is released when an electron is added to a neutral atom. It increases diagonally upward and to the right of the periodic table.

Josephine Lu 4L

I think it's because with the way the formal charges turn out, this configuration is more stable.

Josephine Lu 4L

I agree that there shouldn't be any exceptions to periodic table trends. Generally, ionization energy decreases down a group and increases across a period. Electron affinity is highest for elements in the top right corner of the periodic table.

Josephine Lu 4L

I think that going to the peer learning sessions are very helpful. I have gone to quite a few over the past few weeks, and the UA's have helped me understand the material better! Also listening to other students' questions is very useful too.

Josephine Lu 4L

Ionization energy is the energy needed to remove an electron from an atom in the gas phase. The further an electron is from the nucleus, the easier it is to remove. Ionization energies tend to decrease down a group (because of shielding from shells) and increase across a period (because greater attr...

Josephine Lu 4L

How do you make a New Post on Chemistry Community? I only know how to post replies.

Josephine Lu 4L

Is the unit of work function Joules, or Joules per photon?

Josephine Lu 4L

On Test 2, would we be required to draw the different types of orbitals or identify various diagrams of orbitals?

Josephine Lu 4L

Is work function the same thing as threshold energy?

Josephine Lu 4L

Heisenberg indeterminacy is the principle that the measurement process influences the outcome. For example, light (photons) shined on an electron will change the pathway of the electron and cause uncertainty in its distance.

Josephine Lu 4L

For each of the series, the principal quantum number for the lower energy is different. For the Lyman series, the lower energy level is n=1. For the Balmer series, the lower energy level is n=2. For the Paschen series, the lower energy level is n=3.

Josephine Lu 4L

Dr. Lavelle gave an interesting method of how to think about combustion: eating food + breathing in oxygen --> breathe out CO2 + H20. Hope this analogy helps!

Josephine Lu 4L

I'm confused about what exactly are formula units too. On problem E9 part b, the answer is written in terms of atoms as formula units, but isn't MgSO4 * 7H2O a molecule?

Josephine Lu 4L

Yes, we are turning in 7 problems for homework. However, even though we are only turning in 7 problems, Lavelle encourages us to do as many homework problems as possible so that we understand the material fully. (:

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