CHEMISTRY COMMUNITY

Alana Sur 3B

Pre exponential factor is A and you use the arrhenius equation to solve for it : k = A x e^(-Ea/RT)

Alana Sur 3B

Yes, that's correct

Alana Sur 3B

What exactly is frequency factor

Alana Sur 3B

The equilibrium constant K is equal to the ratio of the rate of the forward reaction to the rate of the reverse reaction.At equilibrium, the rate of forward and reverse reactions are equal

Alana Sur 3B

I think macroscopic reversibility is when one assumes that the intermediates of a forward and reverse reaction are the same. This occurs when the rate constant of the forward reaction is much larger than that of the reverse reaction

Alana Sur 3B

to convert from natural log (ln) to log, we multiply log into 2.303

Alana Sur 3B

Can we say that it is expansion work because the number of moles increased?

Alana Sur 3B

We use a platinum electrode on whichever side does not have a solid. It could be both or only one of them

Alana Sur 3B

state functions do not depend on the path to obtain that state - only the final and initial values matter. Energy, pressure, temperature are examples of state functions

Alana Sur 3B

If a reaction requires heat to form the products (endothermic), then an increase in temperature will favour the formation of products. If a reaction releases heat when forming the products (exothermic), an increase in temperature will favour the reverse reaction, i.e the formation of reactants.

Alana Sur 3B

Kb is boltzmann's constant, which is given in the equation sheet.
for part two, we calculate :
w = orientations ^ # of molecules.
delta S = Kb x w
delta S = (1.38x 10^-23) (4^64)

Alana Sur 3B

His post says he'll upload them by 9am on saturday

Alana Sur 3B

If we're given just the balanced equation and no other information, can we figure out the order of the reaction?

Alana Sur 3B

because natural log of any value greater than 1 is positive. the formula used is E = (RT/nF)(ln K)

Alana Sur 3B

Are calomel electrodes anodes? what do we need to know about them?

Alana Sur 3B

It's a typo

Alana Sur 3B

From what I've understood, you include it only when it's in the given equation. You can't combine ions though, just write them as given in the equations

Alana Sur 3B

we use Cv to calculate the heat capacity of an ideal gas with constant volume. You add the two delta S values

Alana Sur 3B

Usually, the anode is on the left side of the salt bridge and the cathode is on the right

Alana Sur 3B

The electrochemical series is a series of electrodes arranged according to their decreasing order of standard reduction potentials.

Alana Sur 3B

I wasn't sure how to write the equation for this because of the NH3+ :

Self-Test 12.14A Estimate the pH of 0.10 m CH3NH3Cl(aq), aqueous methylammonium chloride; the cation is CH3NH3+

Alana Sur 3B

Can someone pls explain why an equation that interconverts the compounds determines the more stable compound?

Alana Sur 3B

When calculating change in Gibbs free energy, when do we use the equation with change entropy and enthalpy and when do we use the gibbs free energy of formation of products and reactants? In the textbook (6th ed), the questions just say refer to appendix 2A but some of the solutions use entropy and ...

Alana Sur 3B

I think it's because the system loses energy

Alana Sur 3B

So basically a system is identified by its interaction with its surroundings. - An open system: Matter and energy can exchange with the surroundings. Eg. A glass of water - The water can evaporate and the glass does not provide any insulation. - A closed system: The amount of matter is fixed, but th...

Alana Sur 3B

Is this applicable to moles of gas only?

Alana Sur 3B

Hi, I think Professor Lavelle said we'd get out final exams back in week 3. Does anyone know where we can get them?

Alana Sur 3B

I'm getting a complicated polynomial equation and I'm pretty sure it's incorrect. Can someone please explain how to do this question? A vial of SO2 (0.522 mol.L-1) and O2 (0.633 mol.L-1) react and reach equilibrium. Calculate the equilibrium concentrations of the products and reactants given that KC...

Alana Sur 3B

Can someone pls explain q24 of the Chemical Equilibrium Part 2 Post Assessment? Q. The equilibrium constant, KP, for the reaction SO2 (g) + O2 (g) ⇌ SO3 (g) at 700 K is 3 x 104. A mixture of SO2, O2, and SO3, each at 65 bars was introduced into a container at 700 K. Is the reaction at equilibrium? I...

Alana Sur 3B

On Prof. Lavelle's website, the link to naming of coordinate compounds says that both are acceptable.

Alana Sur 3B

an acid donates a proton to give a conjugate base. Similarly, a base accepts a proton to give its conjugate acid

Alana Sur 3B

Cations that are small and highly charged have a high polarizing power. So as you go down a group, polarizing power decreases. The order was Cs < Ba < Ca < Li

Alana Sur 3B

I assumed the initial conc = 0.1 and final conc = 0.012, calculated both pH separately and then got the difference

Alana Sur 3B

They're both polydentate. In the q17.33 of the 6th edition, they ask whether carbonato is polydentate

Alana Sur 3B

Magnetic spin

Alana Sur 3B

I don't think chlorito is correct. You can use either chloro or chlorido - they're both on Prof. Lavelle's website. Here's the link - https://lavelle.chem.ucla.edu/wp-conten ... pounds.pdf

Alana Sur 3B

Thanks!!

Alana Sur 3B

When we're writing the formula of coordination compound , does the order in which we put the ligands in the square bracket matter?

Alana Sur 3B

This is sooo helpful, thank you!!!

Alana Sur 3B

If it says geometry, it always means the shape with lone pairs and bond pairs

Alana Sur 3B

will the bond angles for square planar and square pyramidal be less than 90 degrees

Alana Sur 3B

We don't include the products and reactants in liquid state when calculating that^^

Alana Sur 3B

I don't think we don't need to remember the constants but you should know the formula for calculating Ka and Kb The formula for calculating Ka is just -log(PKa) and the formula for calculating Kb is just -log(PKb) right? And that Ka = [Concentration of product1][ Concentration of product2]/ [Concen...

Alana Sur 3B

What is the bond angle for T-shaped molecules

Alana Sur 3B

I don't think we don't need to remember the constants but you should know the formula for calculating Ka and Kb

Alana Sur 3B

Cl can form double bonds due to the presence of d orbitals. The electronic configuration is an expanded octet

Alana Sur 3B

Is there a formula that calculates the pH when the Ka is given?

Alana Sur 3B

So in this case the fact that there are four oxygen atoms bonded to Se at equal angles has no effect because the electron pull is outwards?

Alana Sur 3B

Do we need to know how to solve these kind of questions? It's between 12.13 and 12.14, which is in syllabus.

Alana Sur 3B

Can someone please explain how there's a dipole-dipole interaction in H2SeO4

Alana Sur 3B

I found it easier to calculate hybridization by ignoring the same number of p orbitals as there are pi bonds in a molecule and then determining the hybridization with the remaining orbitals. For example, in HCN, C has one sigma bond with H and one with N, along with two pi bonds. Since there are two...

Alana Sur 3B

sigma(C2sp2, C2sp2) is describing the bond between the two carbon atoms. We can't use C2sp2 because we have to describe the hybridization of both atoms and I think the 2sp2 is just more specific about the principle quantum number compared to sp2

Alana Sur 3B

I've noticed that the TAs don't put the principal quantum number when the question just asks for the hybridization but they use it when the question is about describing a bond (eg. - sigma(C 2sp3 - H 1s)

Alana Sur 3B

Your hybridization was correct - 4 regions of electron density should be an sp3 hybridization

Alana Sur 3B

Yes because we consider a lone pair as one region of electron density, which you need to determine the hybridization.

Alana Sur 3B

yeah, but I think it's a safer option to write the 1 in front of the s orbital of Hydrogen - sigma (C 2sp^3, H 1s)

Alana Sur 3B

Thank you!!!

Alana Sur 3B

Do AX2E and AX2E2 have the same bond angles?

Alana Sur 3B

I think it's because the additional bonding electrons attract the nuclei more strongly and pull the atoms closer together, hence the length is shorter.

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