CHEMISTRY COMMUNITY

Ara Yazaryan 1E

AgBr is being oxidized from 0 to +1, and subsequently Br- is being reduced from -1 to 0. This makes AgBr the anode and Br- the cathode, this is why they are included.

Hopefully that is the correct way to answer your question :)

Ara Yazaryan 1E

That conceptual study guide sounds like a good idea! I may try that

Ara Yazaryan 1E

Which one? The Midterm Review Session or the Midterm answer review? I believe both should have been posted here on Chemistry Community.

Ara Yazaryan 1E

Iso is not taken into alphabetical account, and it comes whenever there is a fork in the carbon substituent chain. For example: "isoethyl"

Ara Yazaryan 1E

I don't believe we will be using the term "sec" quite yet. "Tert" is for when the carbons are perpendicularly arranged in a cross-shape, so you need a minimum of 4 carbons (Butyl).

Ara Yazaryan 1E

Thought this was Appropriate:

Ara Yazaryan 1E

I may be incorrect, however I think Iso- is used when the carbon are arranged in a linear chain. Thus Tert would be used when they are all perpendicular to each other, as seen in the Course Reader. I found this link to be very helpful, and you may as well :) http://web.chem.ucla.edu/~harding/IGOC/C/...

Ara Yazaryan 1E

Significant figures should be computed at the end yo give the most accurate answer possible. If we take sig figs at each step of the problem our answer would have a heavy rounding bias.

Ara Yazaryan 1E

The intermediate can never be part of the rate law since it is consumed in the reaction. When this happens, substitute in for the intermediate in terms of its reactants.

Ara Yazaryan 1E

For this case water is not being included in the reaction, rather the half reaction is occurring in an acidic solution. These means we use water and H+ to balance our oxygen atoms.

Ara Yazaryan 1E

The change in entropy is still the same, and you still would use ln in this case. Yet no work is done in free expansion, so the delta s of the surroundings is zero and q is zero. Only the internal entropy of the system increases in the irreversible process.

Ara Yazaryan 1E

Well the first to you gave are the same reaction, except one is the oxidation and the other is the reduction reaction. As for the third reaction, that is for the formation of water from diatomic hydrogen and oxygen. Thus the question would have to explicitly state "water is formed from hydrogen...

Ara Yazaryan 1E

Electrolysis is whenever an electron current is used to drive a reaction that may otherwise be non-spontaneous (+delta G). Redox reactions are thus often examples of electrolysis since they may not always be spontaneous and electrodes provide an electric current.

Ara Yazaryan 1E

If I am correct yes the order does matter. This is based off whether it is the anode or cathode, in which it would go from the reactant being reduced or oxidized to the end result. Someone else feel free to add input.

Ara Yazaryan 1E

An electrode is always needed in an electro-chemical reaction. That is how electrons are transferred in the first place, a key component of any cell system.

Ara Yazaryan 1E

Intensive properties can be considered more useful in Chemical Applications because they are particularly helpful in the identification of chemical substances since they are not dependent on the amount of matter present in a system (as extensive properties are). For example, think of a colorful ruby...

Ara Yazaryan 1E

BetcyGaspar_3C wrote:I do believe we use the equation deltaS=qrev/T,by plugging in 200J/(273+20) you will get the answer.

Thank you so much!

Ara Yazaryan 1E

Could someone explain to me how to get #10 please? I am confused because we do not know the final temperature.

Ara Yazaryan 1E

It depends on what the question asks for, it could be either kJ or J depending on what is given and what is most convent to use for the answer.

Ara Yazaryan 1E

I believe we would use it to find the specific heat (C) of a monatomic gas, however it is also used to prove that equation.

Ara Yazaryan 1E

If I am correct we will be using it in the second half of the quarter, Dr. Lavelle should tell us when we should start bringing it to class.

Ara Yazaryan 1E

In this case, energy is released when TNT is consumed. Thus it would be positive since the surrounding environment is getting an increase in energy. If the reaction was endothermic (e.g. bonds were formed) then the reaction energy would be - since energy is used up.

Hope that helps!

Ara Yazaryan 1E

If I am correct the 3/2 is simply given by the formula for the molar heat capacity of a monatomic ideal gas at constant volume. That is my opinion, but it amy not be correct so someone else's input would be helpful.

Ara Yazaryan 1E

Because the negative sign signifies that energy is released from the system. I think you were under the impression that this was akin to a number-line sort of scale, which is not the case here. -300kJ realized by a system is thus more work than -200kJ. Hope that helps, cheers.

Ara Yazaryan 1E

The table is simply used to help determine the change in moles of reactants and products before and after a reaction takes place. Thus you would use it in acid base reactions, titrations, etc.

Hope that helps :)

Ara Yazaryan 1E

Assuming you mean Chapter 13, problem 17: The problem is asking you to generally predict the pH region (acidic or basic) where these buffers will be effective. Thus for part c, since KHP04 can give off a hydrogen it would act as an acid and thus be most effective as a buffer above pH 7., and Potassi...

Ara Yazaryan 1E

Well log is short for logarithm, which is an essential way of expressing pH. pH describes the concentration of H+ ions in a solution, thus describing the strength of the solution (i.e. it's parts of Hydrogen or PH). Log is simply used to appreviate. Conversely there is pOH, as described in the cours...

Ara Yazaryan 1E

If I am correct, it is for the reason you cited. Because Chlorine is more electronegative, it holds onto its electrons. Thus it is more likely to give off an H+ ion, which would thus make it a stronger acid.

Hope that helps! :)

Ara Yazaryan 1E

For your first question, the easiest way is just to memorize the handy list Dr. Lavelle gave us. I guess you could draw out the Lewis structure to find the number of bonding sites in a ligand, but memorization is much easier (at least in my opinion). And for the second question, the prefixes (bi, tr...

Ara Yazaryan 1E

You would omit solids and liquids, including only gases and aqueous compounds.

Ara Yazaryan 1E

Oxalate is bidentate because each of the oxygen atoms serves as an area where oxalate can bind with other atoms. Since it has two oxygen atoms therefore it is bidentate.

Ara Yazaryan 1E

Hello all, I am confused as to when we should use P sub x, P sub y and P sub z in our electron configurations and when we could just write 2p5 or such. I believe I heard Professor Lavelle say that they are interchangeable and that the p sub is merely to help observe the sub-shells. Is this true, bec...

Ara Yazaryan 1E

The only exceptions we are expected to know are Cu and Cr, which in this case would be 4s1 3d5 and 4s1 3d10 respectively.

Ara Yazaryan 1E

You take your valence electrons as everything after the noble gas configuration.

So for example, Zinc would have 12 valence electrons from the 3d10 4s2 that comes after [Ar]

Hope that answers your question

Ara Yazaryan 1E

It's the parts of chapter 2 that wasn't on quiz 1 and all of Chapter 3

Ara Yazaryan 1E

3.19 part e) First take into consideration the actual electron configuration of Ni. When finding out the configuration take into account that the d subshell acts as a lower charge so should be in front of the configuration. So naturally, Ni configuration is [Ar]3d84s2 it is 3d8 because if you count...

Ara Yazaryan 1E

Hello all, Could someone please explain 3.19 part e It asks to give the "ground state electron configuration and number of unpaired electrons for Ni+2" The answer I got was 3d6 4s2 with no unpaired electrons but the answer the text gave was "3d8 and 2 unpaired electrons". Could s...

Ara Yazaryan 1E

Are we suppose to double the speed if its +/- to cover the entire range in all Heisenberg uncertainty problems then? Correct me if I am wrong, but on the Heisenberg problem in the practice quiz we turn in we do not double it because we want the minimum error and adding that uncertainty would rather...

Ara Yazaryan 1E

Personally I balance metals or other elements that are not H or O (such as C, N, Al, etc...) before I balance H and O. This is because most of the time there is some product such as H2 or H20 that i can use to help balance the equation at the end.

Ara Yazaryan 1E

Glancing through the usernames, I noticed that I am certainly not the only Armenian student in Chemistry 14A.

Would any other Armenians care to form a study group? (All other nationalities are welcome too of course, I just want friends to study with! :) )

Ara Yazaryan

Ara Yazaryan 1E

Well the purpose of this example is to show that ion fact electrons do not collapse to or are localized at the nucleus. Rather they exist in electron energy levels or "shells" around the nucleus, many times the diameter of the nucleus itself. The Indeterminacy principle shows us that the a...

Ara Yazaryan 1E

Yea you ALMOST finished the problem. What you found is the Energy of the PHOTON, but it is asking for the KINETIC energy. Therefore, because E(photon) - E(work function) = E (excess/kinetic energy)... 1.024998 x 10^-18 - 7.22 x 10^-19 (gotten from the previous problem) = 3.03 x 10^-19 J, which is B...

Ara Yazaryan 1E

Question Number Two To start off: Convert nanometers to meters since that is the unit we need to divide the speed of light by. 1 nm = 10^9 meters Thus 194 nm turns to 1.94 x 10^-7 m Then plug this into speed of light = (wavelength)(frequency) 3 x 10^8 = (1.94 x 10^-7)(frequency) Thus you get the fre...

Ara Yazaryan 1E

So for your first question.

Energy = (Frequency)(h)

h is Planck's constant which is 6.63 x 10^-34 J.s

So if you plug it into the formula you get:

(1.09x10^15)(6.63 x 10^-34) which thus gives you 7.2267x10^-19 J

:)

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