CHEMISTRY COMMUNITY

emily gao 1C

no we don't need to know how to actually integrate it (though it helps to understand how it works) just know the different orders and their respective equations that are given on the equation sheet

emily gao 1C

i'm pretty sure it's always rate of decomposition of reactants but the unique rate should be the same for each of the species

emily gao 1C

the fast steps will be at equilibrium

emily gao 1C

the general rate law should only have reactants for the reaction as a whole. intermediates aren't found in the general reaction equation because they are created and then used up, so they wouldn't be in the rate law

emily gao 1C

the slow elementary step is the rate determining step. the other steps are fast so you assume those steps are at equilibrium so the fwd rate is the same as the rvs rate.

emily gao 1C

it's a type of electrolytic cell that has the same electrode on both sides. It relies on concentration gradients to run; so it's not as powerful as normal galvanic cells

emily gao 1C

you can half fractional half reactions--> the rate law goes to a 1/2 power, etc

emily gao 1C

yes you can; the total rate order just has to be 2; so one or more of the concentrations should be to the 0th order. the units will still be 1/M/s

emily gao 1C

emily gao 1C

yeah you can figure it out by looking at g = h -ts; the units on the right side have to be the same as the left, so it's J, kJ or J/mol, kJ/mol

emily gao 1C

you just rearrange the formula to find what Q is. and to find K, delta g is 0, so e is 0, and then continue to solve the equation.

emily gao 1C

so because the anode is the one being oxidized, the e standard reduction potential gives the reverse e standard. therefore, the e standard equation is like if you had the other method where you write the 2 half reactions out and you add the two values, but they built in the - sign into the equation ...

emily gao 1C

i think it's just voltaic cells? he hasn't really gone over electrolytic cells in class?

emily gao 1C

yes we need to know the order of the cell diagram and also how a salt bridge cell works overall

emily gao 1C

bc youre doing the method of e standard = e (cathode) - e (anode). the negative sign is built into the equation.

emily gao 1C

what processes should we know for the midterm- isothermal reversible expansion? is there others that we have to know?

emily gao 1C

heat is released/absorbed in any rxn-- it matters more w gibbs free energy calcs bc delta g tells us if a rxn will be spontaneous or not. delta g= delta h - t delta s
this matters for things like atp hydrolysis.

emily gao 1C

it's because bond enthalpies are written as positives, instead of negatives, so you do delta h of reactants - delta h products to get the rxn delta h

emily gao 1C

its usually at 25 celsius bc that's the temp that the scientists got all the standard value table measurements from. eg delta H standard (H2) at 25 degrees C

emily gao 1C

H=U + PV, so delta H = delta U + P delta V
So if so no change in delta V means that delta H = delta U.
and so if P is same and v is changing and no internal energy is changing then delta H = delta P * v

emily gao 1C

they are the same equations? q=mc* delta T and q= mL talk about heat. and @ constant P q= delta H

emily gao 1C

enthalpy is in some kind of joules (J, kJ, etc). kJ/mol is just per mole what is the enthalpy
aka its not too significant

emily gao 1C

yes to find the change in enthalpy: do bond energy (reactants) - bond energy (products)

emily gao 1C

yes bc exothermic is - and endothermic is +.

freezing: exothermic: delta h is negative
melting: endothermic: delta h is positive

emily gao 1C

You can also always just switch it back to Ka/Kb then look at how large Ka/Kb is. Greater the Ka/Kb, the stronger it is, more it dissociates.

emily gao 1C

The larger the equilibrium constant, the more a compound dissociates (look at the formula for K: [products]/[reactants])

emily gao 1C

I'm pretty sure they'll always give you the formula? or like acids are called acids: eg acetic acid, hydrochloric acid; bases are hydroxides eg: barium hydroxide

emily gao 1C

if the gas that is added is not involved in the reaction (aka isn't in the equation), then it is inert and won't affect equilibrium

emily gao 1C

if q = k then the reaction is at equilibrium

emily gao 1C

in the chemical equation, they're given as for example Cl2(s) vs Cl2(g). So when its a solid, or a liquid (l) then it wouldn't go into the K/Q equations because their concentrations don't change.

emily gao 1C

so momentum exists even if there's no mass--> E=pc :( i didn't know this either

emily gao 1C

All Lewis Acid/bases are Bronsted Lowry acid/bases but not all Bronsted Lowry acid/bases are Lewis acid/bases. But B-L describes proton transfer while Lewis describes electron pair mvmt.

emily gao 1C

aqua: OH2
Ammine: NH3
carbonyl: CO
nitronyl: NO
ethylenediamine (en): Nh2Ch2Ch2Nh2
diethylenetriamine (dien): Nh2Ch2Ch2NhCh2Ch2Nh2

emily gao 1C

why for sodium bisoxalato (diaqua) ferrate (iii) is oh2 written before c2o4

My answer was: Na [Fe (C2O4)2 (OH2)2]

but apparently its: Na [Fe (Oh2)2 (C2O4)2 ]

emily gao 1C

Can hybrid orbitals make both sigma and pi bonds, or only sigma bonds?

emily gao 1C

For this question, why does the bond length matter more than electronegativity & polarity for determining bond strength?

CF4 bond strength > CCl4 bs > CBr4 bs

emily gao 1C

How can we determine which atoms go where in CH2F2. I looked it up to find that F takes the spot above the central molecule C. Is there a specific reason why or is it just how we generally write it (and we could easily flip the atomic placement)?

emily gao 1C

First, determine whether a molecule has a dipole or is capable of making a hydrogen bond (N, O, F is bonded to H). Then see if the dipoles cancel out (using molecular shape). If btwn 2 molecules there are dipoles that aren't being cancelled out, it would be dipole-dipole. For 1 dipole, and 1 nonpola...

emily gao 1C

seeing that london dispersion forces are induced dipole-induced dipole attractions, more distortion means that its more likely for these intermolecular attractions to happen. P much all london dispersion forces are super weak; however, the amount of ldf add up which is why they are very important in...

emily gao 1C

What is the difference between molecular and electron geometry? eg: how can you tell which one (like tetrahedral) is which, and are they mutually exclusive?

emily gao 1C

no h-bonding is only for polar molecules, more specifically for H-F, H-O, H-N bonds

emily gao 1C

tetrahedral has 4 bonding regions, while trigonal planar has only 3. When you look at the lewis structure of the central atom, look at how many bonding regions it has.

emily gao 1C

I'm pretty sure it does decrease with increased length. Refer to Coulomb's law: as radius increases force of attraction decreases

emily gao 1C

these are also instantaneous attractions bc the induced dipole comes from a momentary fluctuation in an atom's electron cloud.

emily gao 1C

lone pairs take up more space/ repel bonds more so it will change the measured bond angles.

emily gao 1C

hydrogen bonds have a stronger attraction than other intermolecular attractions; thus, it takes more energy to change phase, so the melting/boiling points will be higher

emily gao 1C

Copper(I) is Cu+ and Copper(II) is Cu2+

emily gao 1C

i feel like we should probably know basics (eg electron pair is shared)

and pretty much when you draw the molecule's Lewis structure where you would need one species to share an electron pair w the other--> thats a lewis acid/base pair

emily gao 1C

does this rule not apply to seaborgium and roentgenium (which are under the same group as Cr/Cu but 1 period down)?

emily gao 1C

we don't need to know how to use schrodinger's eqn tho we have to know where it comes from & what it does

emily gao 1C

N has no impact on the number of electrons directly; however it determines what l can be. So when l=0 (s orbital shell) there can only be 1 orbital which fits 2 electrons

emily gao 1C

We should probably know that the equation is solved by the 3 quantum numbers n, l, and m.

emily gao 1C

I thought that we wouldn't need to use wave function equations nor use any calculus.

emily gao 1C

there are higher energy orbitals that theoretically exist--> g would be the next one which would require 121 protons

emily gao 1C

In lecture, Prof. Lavelle mentioned that Ml values could be named like x, y, and z. I was wondering for bigger orbitals like d, or f, what alpha letters would be used to represent the different Ml values.

emily gao 1C

i thought other equations have similar like formats with much more complex values (even for atoms with only 1 electron, not to mention the ones with multiple electrons), but in general we don't have to know that for this class.

emily gao 1C

When we do hw, should we use 3.0x10^8 m/s for the speed of light, or a more accurate value?

emily gao 1C

When I do limiting reactant/empirical formula problems I usually find the ratios then instead of multiplying to a whole number, I first look to see if it converts to some nice fraction-- eg 4.33 = 13/3 or 4.63-4.68 = 14/3, then solve from there. :)

emily gao 1C

Yes your way works: the number might not be exactly the same if you rounded each step--> general rule: keep all the sig figs until the end

emily gao 1C

For exams, will we need to memorize all the formulas that we discussed in class?

emily gao 1C

Yes use whatever sig figs is the least accurate in the given: aka if you have 3, 4, 5 sig figs given to you in the question: respond with 3 sig figs.

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