CHEMISTRY COMMUNITY

alanaarchbold

Are there any equations that won't be given on the formula sheet that we have to memorize?

alanaarchbold

You determine the order of one reactant each time so you want to pick the experiments where the only variation is the concentration of the reactant you are studying. But say like in 6th edition 15.19 the solutions use experiments 2 and 3, when the concentration of 2 is equal to the concentration of...

alanaarchbold

I also can't figure this out but it's clear that the solution is flawed because it also says 37'C is equal to 3130 K

alanaarchbold

A is just the frequency factor. Basically, if A increases the rate will increase. If you're looking at a plot, lnA is the b in y=mx+b, or the y-intercept.

alanaarchbold

my TA said it will tell us

alanaarchbold

Would an adsorption catalyst work differently in an equation? Or should I just know what it is compared to absorption

alanaarchbold

It helps for when you're finding the units for k because the units are M^(1-n) x t^-1 where n is the overall order

alanaarchbold

Did Lavelle say how harshly he will grade on units/sig figs on the final?

alanaarchbold

How do you know which experiments to use in those charts to determine the orders for each reactant?

alanaarchbold

What was the right answer for the gibbs free energy question on test 2 about rusting? like if it was spontaneous or not? and why?

alanaarchbold

Can someone list the steps for the pH question from test two please

alanaarchbold

since the anode was reversed and the sign changed, we add -.34 and .77. However, if we didn't reverse it, it would be .77-.34, which would give the same answer. Basically, if you use the voltage from the original voltages given, you subtract it. If you use the reverse anode reaction voltage, you add...

alanaarchbold

it relates to equilibrium because K is the equilibrium constant. It helps to find the K at different temperatures.

alanaarchbold

K will help tell us if the reaction is spontaneous, nonspontaneous, or at equilibrium, depending on its value. If you increase the partial pressure of the product, deltaG becomes more positive, and if you increase the partial pressure of the reactant, deltaG becomes more negative.

alanaarchbold

it represents the number of moles. however, you find this by balancing the equation and taking the number of electrons into account so that it's balanced.

alanaarchbold

It's more based on the anode and cathode. So say you have Cu2+(aq) + 2Cr2+ (aq) ---> 2Cr3+(aq) + Cu(s). Since the Cr is the one losing electrons, it will be on the anode side and since Cu is gaining electrons, it will be on the cathode side. So it will look like: Pt(s) | Cr3+, Cr2+(aq) || Cu2+(aq) |...

alanaarchbold

finding the number of electrons is based on the change in the molecules. So say there's Cu2+ and it becomes Cu3+, it will have lost an electron and it will look like Cu2+ ---> Cu3+ + e-. Thus, this is the anode and it lost one electron.

alanaarchbold

I've never had Lavelle before and I was wondering whether the questions on midterms/finals are mostly math based/problem solving or are there conceptual questions asked as well? They're mostly math based/problem solving but there are still conceptual questions, they're just worth less points./A lot...

alanaarchbold

Should 14BL and 14C be taken at the same time to graduate on time?

alanaarchbold

Will we have to memorize conversions such as 1 atm=101325 Pa?

alanaarchbold

On the midterm does anyone know if we have to convert our answers for delta U into joules? Or can we leave it as L.atm?

alanaarchbold

In one of the examples from Monday's lecture, O2 didn't have any delta HF value. I was wondering why that is?

alanaarchbold

How do you find the J/mol/degrees celsius number (sorry I forgot the name of it)? In this question that number was different for constant volume and fro constant pressure but how is it found? Thanks

alanaarchbold

Do you guys know if he'll add modules for other topics?

alanaarchbold

I don't know if I can explain this that well but think of it in terms of that graph Lavelle had on his presentation. It takes about 41 kJ for vapor to become a liquid at 100 degrees Celsius, but it's still at 100 degrees so it has to use even more energy to go to a lower temperature. Meanwhile, it d...

alanaarchbold

In method 2 I just wanted to confirm. So when the bonds break on the reactant side that releases energy right? But then it requires energy to form the new bonds on the product side? Does it take the energy from the broken bonds and then is whatever that's left over the net enthalpy?

alanaarchbold

Lavelle briefly talked about how one heartbeat takes 1 joule of energy. Does that energy come from the bonds breaking in glucose?

alanaarchbold

In method 1, when adding the two equations do you cancel out molecules if there's one on the reactant side and one on the product side?

alanaarchbold

In method 1 from the last lecture do the 2 NO's cancel each other out?

alanaarchbold

I meant like it would just say you have molecule A, B, and C. How do you know the equation for that if they just tell you what they are? Like how do you know A and B form C or if C breaks down to form A and B?

alanaarchbold

Why don't the molar concentrations of solids and liquids change in a reaction?

alanaarchbold

Would it be wrong if on a test we used concentration in the K equation if the reaction refers to gases? Or would we have to use partial pressure? (and vice versa for aqueous)

alanaarchbold

For some of the homework questions, it would just say the molecules and not distinguish if they were reactants or products. This is stupid but how do we know which are reactants and which are products?

alanaarchbold

If you use a weak acid, it won't completely ionize in solution, so the pH will be higher

alanaarchbold

I know that stronger polarizability has to do with size, so the larger the molecule, the stronger the polarizability. Since Mg2+ has lost two electrons, it'll be smaller than Li+ because that only lost one electron. And then since Br is further down on the periodic table it's larger than P, so it's ...

alanaarchbold

If a conjugate base is more stable, the acid is more likely to donate a proton. So the more stable the conjugate base, the stronger the acid (because it'll donate a proton a lot easier).

alanaarchbold

but why does water always seem to be in an equilibrium reaction? does it basically mean that if it's mixed with water it will always be switching back and forth between the reactants and products?

alanaarchbold

Why are there double arrows in reactions with water?

alanaarchbold

Does pH increase or decrease as H+ concentration increases and why?

alanaarchbold

Do we have to know what cis and trans is for naming? What is that if we do?

alanaarchbold

On the naming coordination compounds link it gives the structure for ethylenediaminetetraacetato but I was wondering what the formula for that is? Also, does anyone know if the test only uses the compounds from the naming coordination compounds link?

alanaarchbold

Why aren't weak bases completely ionized in water?

alanaarchbold

This is stupid but are the charges in acid and base reactions found from using formal charge?

alanaarchbold

why is calcium oxide called quicklime and calcium hydroxide called slaked lime

alanaarchbold

I think we need to be able to identify shapes so we might have to know the bond angles

alanaarchbold

I believe it's because it's t-bone shaped and the three dipoles don't cancel each other out, causing it to be polar

alanaarchbold

I think s character is like how much s is in a hybridized orbital. So for example in an sp3 orbital, it's 25% s character and 75% p character.

alanaarchbold

How does the shape and conformation of a molecule determine its biological activity?

alanaarchbold

How does hydrogen bonding explain higher melting points?

alanaarchbold

What is the relationship between shape and boiling point? Like I know if it's rod-shaped there's a stronger interaction because of the larger distance, but what does that have to do with its higher boiling point?

alanaarchbold

as the intermolecular attraction increases, vapor pressure decreases

alanaarchbold

I think it will be however many he teaches us in lecture and I'm 99% sure they'll have to be memorized.

alanaarchbold

I believe there are five bonds around the central atom and three of them are along the equator with 120 degree angles and the other two are at the axis with 90 degree angles i'm pretty sure.

alanaarchbold

So formal charge doesn't really have anything to do with resonance?

alanaarchbold

Make sure the element with the lowest ionization energy is in the center.

alanaarchbold

I believe there are 5: linear, trigonal-planar, tetrahedral, trigonal-bipyramidal, and octahedral.

alanaarchbold

Does resonance somehow affect the shape of structures?

alanaarchbold

Since the test covers fundamentals, quantum, and bonding I think it will be similar to our usual tests where it's mostly free response with some conceptual questions

alanaarchbold

I know it says to emit c on this problem but how would you find how many unpaired electrons there are for this problem?

alanaarchbold

Can someone please explain what coulombic attraction is

alanaarchbold

Wait what does hydrogen do in that situation?? Can you explain that better please

alanaarchbold

I don't know the answer to 2 and 3 but you check your grades by going to the study list and then going to chemistry and then click on grades

alanaarchbold

How do you correlate x, y, and z when there are more than three magnetic quantum numbers?

alanaarchbold

Will tomorrow's lecture information be on Wednesday's test?

alanaarchbold

Can someone pls explain how the wave model shows that electrons have quantized energy states

alanaarchbold

I know some people were saying that there's an equation that combines E=(-hR)/(n^2) and E=hV. Does anyone know what it is?

alanaarchbold

I know he went over this but I still don't get it. Why are there bigger spaces between certain quantum levels? Like the space between n=3 and n=2 is bigger than the space between n=4 and n=3.

alanaarchbold

We don't know until end of quarter.

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