CHEMISTRY COMMUNITY

dgerges 4H

you don't multiply cell potential, only the coefficients in the half reaction

dgerges 4H

What exactly do we have to know about collision theory for the final?

dgerges 4H

find k using the half life equation then use integrated rate law equation for a second life reaction. Ainitial should be 1 and Afinal should be 1/16

dgerges 4H

usually look for the unknown the question is asking for and list out the values they give you to know which equation to use.

dgerges 4H

most problems don't assign points for sig figs because they're appointed for something else, but with as many points that are on the final, I wouldn't be surprised if they count for something.

dgerges 4H

because half life of any quantity of a first order reaction is the same, it'll take the same time to halve no matter how much it started with

dgerges 4H

The higher the K the lower the stability of the reactants and higher the stability of the products

dgerges 4H

Catalysts don't actually make the reaction slower or faster, what it does is it offers an alternate pathway in which the activation energy is lower, thereby making the reaction proceed more completely with a given energy.

dgerges 4H

what do we do when the reaction isn't acidic. add oh- instead?

dgerges 4H

he has also put a homework question on every test i believe

dgerges 4H

a negative gibbs free energy means it is spontaneous, unlike a negative entropy which means its nonspontaneous

dgerges 4H

there must be a solid in the reaction so if there isn't one we add Pt(s) in place

dgerges 4H

Why is Q listed with both Pressures on top and both concentrations on the bottom on the solution manual? I thought Q was Products over reactants?

dgerges 4H

this is because the ka of that reaction relates to h3po4 losing it's first electron and ka2 is h3po4 losing its second electron or h2po4- losing an electron

dgerges 4H

deprotonation is losing an electron, so ka2 would be losing two electrons

dgerges 4H

it's the second deprotonation of h3po4
the first would include h2po4- in the product, the second will include hpo4^2- in the product

dgerges 4H

does anyone know when we'll get our midterms back?

dgerges 4H

thank you!!

dgerges 4H

10. Michael asks me for water with no ice at a dining hall. Just to spite him, I measure 25.0 g of ice at 0.00 oC and drop it into 265 mL of water at 25.0 oC. What is the final temperature of the water? i know we set qice=-qwater and from that i got a T of 296.91K. Now to find the final answer do I ...

dgerges 4H

with a corresponding q=-11.45kj?

dgerges 4H

I also got that the other part of w=9.12 from w=-pdv. so i got a total of 11.45kj or 1.145x10^5j for w. is this correct?

dgerges 4H

what was the full answer for w on #6? I got that part of it is 2.33KJ from the w=-nrtln(v2/v1)

dgerges 4H

skipping around is kinda necessary for the homework

dgerges 4H

i would stick to outline 3, but the homework kinda requires you to read because we haven't gone over too much in lecture so far

dgerges 4H

J is the SI unit, but if the rest of the problem is worked out in kJ then probably use that. on tests they'll probably specify

dgerges 4H

yes, we usually get our tests back exactly a week after we take them

dgerges 4H

the horizontal lines represent the phase change and the length of the line represents the energy added over time

dgerges 4H

^^ but yes, we will mostly be using SI units which includes joules

dgerges 4H

^^divide kw by the kb for nh3 and you'll get the ka for nh4+

dgerges 4H

an exothermic reaction gives off energy as heat for ex. and has a low activation energy, an endothermic reaction requires more energy and will take it from the surroundings

dgerges 4H

you can know it's okay to use it if the K is below 10^-3!

dgerges 4H

inert gases are just basically saying noble gasses

dgerges 4H

the same goes for Kb and Bases!

dgerges 4H

Ka reflects how much the acid will disassociate in reaction so a high Ka(higher than 1000) will indicate it being a strong acid and a low Ka(lower than .001) will indicate it being a weak acid.

dgerges 4H

Acid's and bases will probably be preferable, but in preparation for the test I'm sure you can do a mixture without it being an issue

dgerges 4H

yeah i think so because oxidation is a process that takes electrons away, leaving the elements with positive charges

dgerges 4H

it's a tetrahedral shape so i don't think the angles would allow for the dipole moments to cancel out

dgerges 4H

becca_vandyke_4b wrote:Are we going to get the same equation sheet for the final thats been on the tests? Trying to figure out if I need to memorize any equations.

yeah we're probably gonna get the same equation sheet

dgerges 4H

"KBr dissociates into K+ and Br-. Br- reacts to make HBr, a strong acid. Since Br- is the conjugate base of HBr, it is weak. K+ is also weak so the two weak components sort of offset and have no real effect on the pH, making it neutral."

dgerges 4H

I think less than 180 is also acceptable if you're considering the angle created by the top, middle, and bottom atoms in this structure

dgerges 4H

The class isn't based on a curve of our own class, but all the classes before us. This means that he has taken the averages from previous classes and uses them as a guideline for how grades should be set

dgerges 4H

using the lewis formula can be helpful!

dgerges 4H

They tell us about the charge separation in a molecule, the larger the difference in electronegativities of bonded atoms, the larger the dipole moment.

dgerges 4H

The bent shape occurs when there are three total atoms with a lone pair or 2 on the central atom such as on H2O

dgerges 4H

Yeah that's basically it. An example is H2O where there's two lone pairs on oxygen which pushes down the Hydrogen atoms to make room

dgerges 4H

Sulfur, phosphorus, silicon, and chlorine are common examples of elements that form an expanded octet which means they can have more than the usual 8.

dgerges 4H

this is what Dr. Lavelle posted:
"Test 3 covers: End of Bonding from 3.12 (6 Ed.) and from 2D (7 Ed.); and all of Molecular Shape and Structure (see Syllabus and Outlines for details)."

dgerges 4H

It should also be noted that certain atoms like Carbon almost always need to have a formal charge of zero to maintain it's stability

dgerges 4H

some exceptions to the octet rule can be found in the 3rd period in the p block because they have an unoccupied d block that lets them expand past the octet rule

dgerges 4H

Does anybody know how we will turn in homework for Week 8 if we have discussion on Thurs/Fri? Dr. Lavelle said "Hand in homework for Weeks 8 and 9 in Week 9. Therefore in Week 9 discussion section hand in 14 homework problems. These will be excellent preparation for Test 3 during Week 9. Test ...

dgerges 4H

It is also important to note that molecular structure plays an important role in polarity. For example, C02 would be expected to be a polar molecule, since the difference in electronegativity of C and O is large. However, the two O's are on either side of the C, giving it a linear shape. Due to thi...

dgerges 4H

octet rule is the first thing we consider, so as long as you keep in mind exceptions to the octet rule, then you should do octet rule first and check formal charges after.

dgerges 4H

some exceptions to the octet rule can be found in the 3rd period in the p block because they have an unoccupied d block

dgerges 4H

Nonmetals typically have much higher ionization energies which makes them less likely to lose electrons and become cations

dgerges 4H

The outside oxygen atoms both connect to the central oxygen with one double bond and one single bond, but they aren't connected to each other

dgerges 4H

The lewis structure for O3 bent, but not triangular

dgerges 4H

it is absorbing energy

dgerges 4H

"electron orbitals that have the same energy levels are called degenerate orbitals. ... For example, p orbitals consist of three degenerate orbitals that all have exactly the same energy level."

dgerges 4H

No, not everything in chapter two will be tested on this one

dgerges 4H

the slope of the wave decreases which in turn decreases the extent of change in the electric field

dgerges 4H

this is also what i heard

dgerges 4H

yeah they have both properties seemingly at the same time

dgerges 4H

I don't think things like M=moles/liters will be given though!

dgerges 4H

Thank you!!

dgerges 4H

Yes! and in the reaction that creates p4o10 from p4o6 and o2, o2 will be the limiting reactant.

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