CHEMISTRY COMMUNITY

Qining Jin 1F

Since you have the half life and initial concentration, you can solve for k using the equation for second order half-life

t(1/2) = 1/(k[A]naught)

After solving for k, you can use the second order equation

1/[A] = kt + 1/[A]naught

Plug in 2.00M for [A], 5.00M for [A]naught, and k
then solve for t

Qining Jin 1F

Wednesday in Dane's section Consider the following unbalanced half reactions Hg2Cl2(s) + 2e- -> 2Hg(l) + 2Cl-(aq) Enaught = +0.27V 2H+(aq) + 2e- -> H2(g) Enaught = 0.00V b) If PH2 = 2.0 bar, [H+] = 3.16x10^4 M and [Cl] = 0.75M, what is Q? For this problem, how to you deal with partial pressure and M...

Qining Jin 1F

I think for #8 they already gave you the balanced equation. If they didn't then you have to balance it using the steps for balancing redox equations. To find the number of electrons exchanged, you can look at the charges on both side of the equation. If you see any discrepancies between the charges ...

Qining Jin 1F

I think they are always positive. I am pretty sure Dr. Lavelle said something about there is no such thing as a negative rate, at least for what we are doing

Qining Jin 1F

Your dad's been under a lot of pressure lately

Qining Jin 1F

The units for zero order is mol/(L*s)

Qining Jin 1F

Unique rate is calculated by dividing the rate of a species by its stoichiometric coefficient

Qining Jin 1F

A catalyst is something that increases the rate of a reaction. I think photosynthesis is an example

Qining Jin 1F

In the textbook, it ways to write the oxidized form, reduced form; however in the solutions manual, sometimes they have the reduced form before the oxidized form, so I am not sure

Qining Jin 1F

I guess I am trying to ask how do you know what order you put everything in in cell diagrams.

I thought that ions in solution are written in the order oxidized state, reduced state, so I was wondering why Pu3+(aq), Pu4+(aq) written with the reduced state first

Qining Jin 1F

14.17 (a) Write balanced half-reactions for the redox reaction of an acidified solution of potassium permanganate and iron(II) chloride. (b) Write the balanced equation for the cell reaction and devise a galvanic cell to study the reaction (write its cell diagram). anode: Fe 2+(aq) -> Fe 3+(aq) + e-...

Qining Jin 1F

Pt is necessary when both the oxidized and reduced species are in the same solution

Qining Jin 1F

14.23 For each reaction that is spontaneous under standard conditions, write a cell diagram, determine the standard cell potential, and calculate delta G naught for the reaction: c) Cr2O7^2- (aq) + 14 H+ (aq) + 6 Pu3+ (aq) S -> 6 Pu4+ (aq) + 2 Cr3+ (aq) + 7 H2O(l) The cell diagram is Pt(s)IPu3+(aq),...

Qining Jin 1F

The textbook says that "The natural progression of a system and its surroundings (which together make up “the universe”) is from order to disorder, from organized to random, from lower to higher entropy." Thus, I think that decreasing the entropy of the universe defies the second law of th...

Qining Jin 1F

If you are given enthalpy (H), then you can assume constant pressure, since q=deltaH under constant pressure

Qining Jin 1F

Yes I think so

The textbook says "deltaU=0 for the isothermal expansion (or compression) of an ideal gas"

Qining Jin 1F

I think it is talking about the surroundings

Qining Jin 1F

I think it's 0

Qining Jin 1F

I do not think it is

Qining Jin 1F

A spontaneous reaction is a reaction that is favorable (with a negative deltaG)

Qining Jin 1F

We use S=-q/T for the entropy at 800 K because heat released, and we use S=q/T for the entropy at 200 K because heat is absorbed by the reservoir

Qining Jin 1F

Also, more work is done in reversible pathways than in irreversible pathways.

Qining Jin 1F

I think some of the main equations we need to know are
q=nC(deltaT)
w=-P(deltaV)
(deltaU)=q+w

Qining Jin 1F

I think my ta said they would not take off points for either, but we should use kj/mol

Qining Jin 1F

In the email that Dr. Lavelle sent us, he said we can pick them up at 4006 Young Hall, Week 3 Winter quarter. But I do not know what time specifically

Qining Jin 1F

Gasses have Cp and Cv (specific heats at constant pressure and volume), but I think solids and liquids only have one value for specific heat

Qining Jin 1F

Specific heat capacity for water(solid) is 2.03 J/g°C, water(liquid) is 4.184 J/g°C, and water(vapor) is 2.01 J/g°C

Qining Jin 1F

You can increase the temperature of an open system and it will increase its internal energy, but I am not sure how effective it is to, say, heat up an open beaker where the heat can just leave

Qining Jin 1F

Not all exothermic reactions are spontaneous, meaning that the reaction will occur without outside influence. Just because a reaction is exothermic doesn't mean that its reactants cannot be found naturally.

Qining Jin 1F

DeltaH is what people usually use, so I don't think we will use qp

Qining Jin 1F

Also in chemistry, exothermic and endothermic refers to the system. Exothermic releases heat (so the surroundings feel warm) and endothermic requires heat (so the surroundings feel cool)

Qining Jin 1F

I think we need to know what the strong acids/bases are

Qining Jin 1F

It can bind twice at the N and 4 times at the O

Qining Jin 1F

The textbook says that "If the complex has an overall negative charge (an anionic complex), the suffix -ate is added to the stem of the metal’s name," so it does not matter if the ligand has a negative charge or not. Because 17.29d has an overall positive charge, no suffix is added to the ...

Qining Jin 1F

I think so? Otherwise you wouldn't know the placement of the molecules?

Qining Jin 1F

To determine the direction of the reaction when given the INITIAL concentrations and a K value, find Q, which equals [C][D]/[A][B] (it looks like k) for A+B->/<-C+D.
And if Q<K, reaction will go forward; Q>K reaction will reverse; Q=K at equilibrium

Qining Jin 1F

I think the strength of acids is based on percent of dissociation; strong acids are assumed to be 100% dissociated in aqueous environments. Strong bases are usually salts with -OH (there are exceptions)

Qining Jin 1F

I think the one electron should be put on the less electronegative atom (central atom) because the more electronegative one will be more attractive to electrons and have its octet filled

Qining Jin 1F

I think all you have to do is determine how many single/double/triple bonds there are. Because there are two double bonds in CO2, there are two sigma and two pi bonds since each double bond has one sigma and one pi bond

Qining Jin 1F

The central atom is always the atom with the lowest ionization energy

Qining Jin 1F

Valence electrons are usually in the outermost s or p block. There is one valence electron in Cu (because of 4s^2) and 7 valence electrons in Br (because of 4s^1 4p^5). They could be in the d block though. For example, Fe has 2 (4s^2) or 3 valence electrons (3d^6 because there are two electrons in o...

Qining Jin 1F

Yes I think that's right

Qining Jin 1F

No. Within the same energy level, s<p<d<f

Qining Jin 1F

They are isoelectronic, but being isoelectronic only means that they have the same amount of electrons, but they still have different properties. Because they have the same number of electrons and Cl- has more protons, the radius for Cl- is the smallest because there are more positive energy attract...

Qining Jin 1F

5p is higher in energy than 5d, so the p shell in group 5 appears after the transition metals

Qining Jin 1F

A full d^10 is more stable than d^9, so the electron configuration is ns^1(n-1)d^10

Qining Jin 1F

1.57 Lines in the Balmer series of the hydrogen spectrum are observed at 656.3, 486.1, 434.0, and 410.2 nm. What is the wavelength of the next line in the series?
How do you set up this problem?

Qining Jin 1F

In the textbook it said that the Lyman series is in the UV region and the Balmer series in the visible light. But it didn't mention the Paschen nor Brackett series. Do you think we need to know which region they are in?

Qining Jin 1F

"Susie, these past two years have been amazing, but recently, I just feel like I've been living a half life..."

Qining Jin 1F

I think you are getting n and l mixed up. n is the number of subshells (the number in front of the letter). The reason there's no 2d orbital is that n=2 consists of only 2s and 2p. l describes the shape, which correlates with the letters, meaning that when you try to interpret quantum numbers, you w...

Qining Jin 1F

Oh my gosh I wrote down CuBr3 instead of CuBr2. Thanks!

Qining Jin 1F

Question:
Calculate the amount (in moles) of (a) Cu2 ions in 3.00 g of CuBr2; (b) SO3 molecules in 7.00 x 10^2 mg of SO3; (c) F ions in 25.2 kg of UF6; (d) H2O in 2.00 g of Na2CO3 10H2O.

Hey can someone show me how to set up part a? I seem to be having a brain fart...

Qining Jin 1F

The information about the temperature and pressure isn't really relevant right now

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