CHEMISTRY COMMUNITY

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viewtopic.php?f=139&t=28011
here is a post about acidic vs basic balancing equations

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We only need to know the pre-equilibrium approach. Steady- State was not covered in class

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Both partial pressures and concentrations can only be entered into Q when the concentration is in M and partial pressure is in bars. You can use expression equating Kc and Kp to understand why this is possible. so for a question like this: Hg2Cl2(s) + 2e- -> 2Hg(l) + 2Cl-(aq) Enaught = +0.27V 2H+(a...

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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 ...

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You had to assume standard conditions, so temperature = 298 K

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No I dont think the second step would be treated under equilibrium. The rate would just be determined by the slow first step. The second step does not go to equilibrium because the first slow step occurs then the second faster step happens. Equilibrium happens when a later step or second step is slo...

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I believe that these coefficients do not affect how we write the rate laws for first and second order reactions. It would affect the unique rate of the reaction and finding the rates of consumption/production for one reactant/product in terms of another reactant/product's rate of consumption/produc...

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What show do Caesium and Iodine love to watch together?
CsI

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I had the same question because in the page in Lavelle's website (https://lavelle.chem.ucla.edu/wp-content/supporting-files/Chem14B/Kinetics_Integrated_Rate_Laws_Examples.pdf) it says "*In the following derivations of the three integrated rate laws, we assume the stoichiometric coefficient &quo...

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What do you call iron blowing in the wind?

Febreeze!

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Magdalena Palavecino 1A wrote:Does the y=mx+b form refer to anything else than the graphs we looked at in class?

No i dont believe so, the y=mx+b is just to help visualize the graphs better

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Why is the integrated first-order rate law for that chemical equation ln[A] = ln[A]0 - 2kt?

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I think a good way to start is to create a graph if you are given a chemical equation and different experimental data.

like this one.

Then, you use the data (like we did in class) to determine the reaction order of each reactant.

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[A] is the concentration of the reactants as the reaction continues. For the forward reaction, the concentration of the reactants decrease, and for second order reactions, the graph is graphed 1/[A] vs. time. So if [A] is decreasing over time, the graph will show a line/slope that is increasing (or ...

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For the quiz 2, we were supposed to assume standard conditions and that is why the temperature was 25 degrees Celsuis or 298K.

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on page 580, it says "the most negative—the most strongly reducing— are usually found toward the left of the periodic table, and the most positive—the most strongly oxidizing—are found toward the upper right."

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What does order of reactants mean?

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make sure when you are given the concentrations or pressure that they are the same units!

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on page 594 of the textbook you can see how current (I) is related to n as n= I*t / F

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Hi I found the explanation from another post!

viewtopic.php?t=3354

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https://lavelle.chem.ucla.edu/wp-conten ... itions.pdf

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Why is the oxidation state for an combined transition metal zero?

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Does the salt bridge transfer the ions Na+ and CL-?

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Here is the link about the topics

https://lavelle.chem.ucla.edu/wp-conten ... rochem.pdf

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Hi I am a little confused about the solutions manual for this problem. Shouldnt delta G = sum of delta Gf (products) - sum of delta Gf (reactants)? but the solutions manual subtracts all of them.

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It doesnt matter which is on the reactant or product side. If Fe3O4 was on the product side (6FeO3 --> 4 Fe3O4 + O2), the delta G would be +391.6 kJ/mol, thus it would mean the formation of Fe3O4 would not be spontaneous and the reaction would favor the reactants (Fe2O3).

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Also during the review, Lyndon asked "when you spill water does the water just stay there?" No because the water eventually evaporates. The process is 1)water @ 298K to water @ 373K 2)water phase change from gas to liquid 3)water @373K to water @298K. I think :D

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so is there an error in the "Errors in Solution Manual" pdf?

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I think because the problem doesnt say that the chemical reaction is isothermal, then delta U will not be equal to 0. THat is why part e asks you to calculate the enthalpy.

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Also remember the equation we use is the Ideal Gas Law, so the change in moles would refer to the gases in the chemical equation

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Does that mean that every element has a higher entropy than the proceeding element on the periodic table? Or does there need to be a large difference in size for the entropy to differ? I think the difference in entropy is because of the energy levels. So the element with more entropy has more energ...

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Why doesnt this problem use Cv or Cp, but uses the equation deltaS=n*R*ln(T2/T1)?

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If the outcome is favorable, it also means that the reaction is favorable, so the reaction is favoring the products. This can be determined from a negative delta G value.

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The delta G is for the reaction. This means that when the delta G is negative, the products are favored. If the delta G is positive, then the reactants are favored

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A good way to see what you need to know on the Tests is looking over the outlines!

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If you do the caculation, the change of Celcius and the change in Kelvin will be the same.

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Yup he announced it today! and on the website
https://lavelle.chem.ucla.edu/wp-conten ... ns_14B.pdf
here is more info!

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The salt bridges allow there to be a circuit because without the salt bridge the anode will stay negative and the cathode side will be positive. The bridge allows for the flow to continue

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If we see a mistake on the grading of the Final are we able to change our grade?

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so for part B the solutions manual divides the enthalpy of reaction by 4 mol C (358.8kJ/4 mol C) to find the enthalpy of one mole of C?

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https://lavelle.chem.ucla.edu/wp-conten ... ations.pdf
here is the one he will be providing on the test

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I think this is because any change in temperature of Celcius is the same as a change in temperature of Kelvin.

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I also have a question about why we use q=C(delta)T instead of q=nC(delta)T

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947 kJ of energy is leaving the system as heat to the surrounding

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In a closed system, only energy is able to be exchanged with its surroundings, but in an isolated system, neither mass or energy is able to be exchanged.

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For Chem 14A we were given a sheet with formulas, conversions, and the periodic table, so I would assume that he will give us a similar sheet, but I am not sure.

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On page 262 and 263, it says that work is calculated under the assumption that the external pressure is constant, so I think we assume constant pressure for (change)U= q+w.

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Here are some links on Lavelle's website on significant figures
https://lavelle.chem.ucla.edu/wp-conten ... OUT_SF.pdf
https://lavelle.chem.ucla.edu/wp-conten ... ussion.pdf

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Also thermometers work because the liquid (mercury) expand or compress depending on the heat transfer between the mercury and the surrounding, so it is a closed system

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Also a bomb calorimeter the mass and energy (ex:heat) of the system is not exchanged with its surroundings.

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I believe that delta H subscript c is the Standard enthalpy change of combustion or the change in enthalpy per mole of a substance that is burned in a combustion reaction under standard conditions. I dont know about the subscript h. I found this on page 291 of the textbook.

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is XeO2F2 polar or nonpolar?

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is CBr2Cl2 polar or nonpolar?

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The equation gives the probability of finding an electron around an atom. The atomic orbitals are a physical representation of the equation

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whats the difference between a Lewis acid/base and a Bronsted acid/ base?

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I think polydentates, which are ligands that bind to the transition metal or central atom more than once, so I think specifically bidentates create a "ring of atoms"

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A change in solvent concentration is insignificant and will cancel out, so solvents like H2O are not used

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Does favoring one side mean that there is more of reactant than product (favors left) or more product than reactant(favors right)?

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So polydentate ligands have more than one bonding site to the central atom?

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I think you should remember the coordination compound names from Lavelle's website.
https://lavelle.chem.ucla.edu/wp-conten ... pounds.pdf

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You can use this link when naming coordination compounds or find it on Lavelle's website
https://lavelle.chem.ucla.edu/wp-conten ... pounds.pdf

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Does hybridization also allow for lower stability?

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I think we put (OH2) or (H2O) when we are writing the ligand's structure to reference which element is attached to the transition metal.

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So does that mean cations have higher polarization power, and anions have higher polarizability?

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Yes, I think you should know those series. Lyman series is Ultraviolet light and electrons ground state is n=1. Balmer series is Visible light and the electron's ground state is n=2.

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I think the book means that that resonance is the hybrid of all the resonance structures, or all the structures together. This is the actual structure of the molecule. 1.5 bond is the average of a single bond and a double bond.

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Schrodinger's equation? I do not think we have to know how to use the equation, just the conceptual idea and what the equation tells us, which is the probability of finding an electron in a certain area.

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Fluorine with a +1 charge is highly unstable because that means it has lost an electron, so now it has 6 valence electrons. However, originally the parent form of Fluorine would have 7 valence electrons, which is one less electron from becoming an octet (most stable). Therefore, having fluoride with...

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Hi I thank you for the clarification. I was just wondering why more electron affinity (the energy released when an electron is added to a gas phase atom) is released when you go across the table.

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Hi I am still a little confused. So do the electrons go to to the 3d orbital for P, S, and Cl?

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He also said in the lecture that the chemical short hands are encouraged to be used on quizzes and tests

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Hi in the lecture, Lavelle said that there are two ions of Iron (Fe) Fe^2+ : [Ar]3d^6 and Fe^3+ :[Ar]3d^5. I was wondering which one is more common? And is there Fe^4+ :[Ar]3d^4?

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I had a similar question will quiz 3 have Heisenberg’s indeterminacy equation and Schrodinger's equation? or will quiz 3 just have Lewis Structures?

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The wavelength 6.94 x 10-38 m is not measurable in an experiment. The electric car sends a wavelength, but it is too small to be measured in an experiment thus it is hard to conclude that there are wavelike properties for an electric car.

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Hi will test 3 have Heisenberg’s indeterminacy equation and Schrodinger's equation? or will Test 3 just have Lewis Structures? Thanks!

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I believe in the lecture Lavelle said that the equations given were for Hydrogen atoms. I do not know if we need to know equations for other elements

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I am also confused about the reason of the negative symbol in the equation.

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Each color has a specific wavelength. Color is the aspect of things that is caused by differing qualities of light being reflected or emitted by them. I do not think color has to do with the "excess" energy leftover when an electron moves up an energy level.

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Someone in my Discussion asked this question and my TA said that the equation for percent change is dividing by the original value. I believe the book had it wrong.

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If it was .5060 and you wrote it in scientific notation, It would be 5.060 x 10^-1 so would there be 3 or 4 sig figs? There would be 4 sig figs in .5060 or 5.060 x 10^-1 because the numbers "5" and "6" sandwich the zero in between them, thus making the first zero significant. fo...

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There would be 4 sig figs in .5060 or 5.060 x 10^-1 because the numbers "5" and "6" sandwich the zero in between them, thus making the first zero significant. for the last zero it is significant because any zero after the decimal point that is not a placeholder is significant. Th...

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I believe 460 has two sig figs because the zero is just a place holder and the period after "898." is supposed to be a decimal point. I think they are mainly used to say that a zero is significant.

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