CHEMISTRY COMMUNITY

MayaKhalil_1L

The OH- is the "leaving group" that the question asks you to identify (which is why it's not shown)....it's not addition bc the OH- is being replaced since it's not part of the final molecule

MayaKhalil_1L

Br2 has a polar-covalent bond, so the delta negative atom is electron withdrawing, therefore attracting the electrons of the bond

MayaKhalil_1L

Hi i was having the same problem, but I've heard from multiple people that for Hardinger you can go to any discussion so it doesn't matter which one you're enrolled in

MayaKhalil_1L

For this one, I put 2-methylybutane. Is this wrong? If so, how would i know it's supposed to be isopentane.

And similarly, for this one I put 6-ethyl-2,3,4,5-tetramethylheptane.

Thanks in advance

MayaKhalil_1L

It should always be drawn from the bond or lone pairs because that is where the electrons are coming from. Arrows are always drawn from electron rich areas to electron deficient.

MayaKhalil_1L

They're nucleophiles that can as an electron source through different atoms because they have lone pairs on these multiple atoms... Hope that helps (:

CN- is a good example bc the atoms are bonded by a triple bond with each atom having a lone pair...therefore each atom can act as a nucleophile

MayaKhalil_1L

Catalysts don't shift equilibrium towards the products. They simply speed up the reaction, and therefore the rate of the reaction. As question 73, part D says, the position of the equilibrium is unaffected by the presence of a catalyst.

MayaKhalil_1L

Could someone explain what they mean by "draw a proposed structure for the activated complex" for this question? Thank you!

MayaKhalil_1L

Can someone please explain what exactly this problem is referring to and how I would go about it?

(Sorry the pictures are out of order)

MayaKhalil_1L

According to the solutions manual, since the vessel is sealed the masses and concrentartions are proportional. Therefore, any change in mass, causes a proportional change in concentration. So it is uneccesary to take the extra steps and convert the masses to moles and then concentrations when you ca...

MayaKhalil_1L

The question is refering to the change in temperature. A change in one degree Celsius is equal to a change in one kelvin, therefore a change of 70 degrees Celsius = 70 k You would get the same answer if you initially added 273 to the final and initial temperature and then found the change between them

MayaKhalil_1L

Ok but also there was one like this on the quiz, comparing HOCl and H2O, and HOCl had greater entropy bc you can make more arrangements (saying it had more mass was wrong). These questions are very contradictory.

MayaKhalil_1L

You would flip the the question with the more negative or less positive standard cell potential because that would allow Ecell to be postitive and therefore spontaneous. Ecell= E(cathode)-E(anode) The equation you flip will be the anode equation, so therefore, if the cell potential is more negative ...

MayaKhalil_1L

The more negative the standard cell potential is, the stronger its reducing strength and and the more positive, the stronger its oxidizing strength is.

Hope that helps :)

MayaKhalil_1L

Standard E must be positive for spontaneity

MayaKhalil_1L

Since these reactions are taking place in basic solutions you must use OH- rather than H+ to balance H's, first I would use the OH's to balance the O's, then i would use h20s to balance the Hs. It can get tricky sometimes because you have to re-balance the O's and H's before finding the right combin...

MayaKhalil_1L

Potassium nitrate dissolves readily in water, and its enthalpy of solution is +34.9kJ/mol. a.) Does the enthalpy of solution favor the dissolving process? The solutions manual says the change in entropy for the surroundings must be a negative number. They then conclude that because spontaneous proce...

MayaKhalil_1L

So first you want to find the standard enthalpy of the reaction, so you would want to manipulate the equations so that there is one mole of N2O5. So divide the second equation by a factor of 2 so that there is only one mole of N2O5 in the products and now you have 2NO + O2-> 2NO2 deltaH=-114.1kJ 2NO...

MayaKhalil_1L

Click on your username in the top right hand corner and choose user control panel :)

MayaKhalil_1L

In a closed system, matter cannot be exchanged between the system and the surroundings but energy can. A good example is a light bulb, physically nothing can go in or leave the bulb, but electricity goes in to power it and it gives off light and heat. In an isolated system, nothing can be transferre...

MayaKhalil_1L

Dr. Lavelle said he would go into more detail regarding the note in parentheses late on, so hopefully it will make more sense when he does!

MayaKhalil_1L

I believe the SSM goes about the problem as is a and b are independent of each other when solving.

MayaKhalil_1L

I'm not completely sure, but I think those are just typos and are actually 2 and 1 respectively.

MayaKhalil_1L

The oxidation number is essentially the charge of the metal. So first you would need to calculate the charges of the other ligands in the complex and those charges plus the charges of the metal should add up to the total charge of the complex. For example, take [Fe(CN)5]2-, The charge of CN is 1-, a...

MayaKhalil_1L

Anytime the charge of the complex is negative, -ate is added to the end of the name. Since sodium has a +1 charge, whatever is in the bracket must add up to a -1 charge in order for the entire complex(including the cation) to be neutral. Therefore, what's in the bracket has a negative charge which i...

MayaKhalil_1L

The coordination number is essentially how many bonds the metal in the complex makes. If there is a chelate, then the number of bond corresponds with what kind of polydentate it is. For example, en is a bidentate because it had two nitrogen atoms that each have a lone pair that bond to the metal. An...

MayaKhalil_1L

I'm pretty sure that's a typo and the "22" should actually be "2"

MayaKhalil_1L

You need to calculate the number of moles of A that is used based off of the moles of A and vice versa. It's difficult to picture without numbers but essentially all you do is calculate the moles in terms of the variables. So the questions says 1 mole of each variable is used: 1mol A x 1 mol B/2 mol...

MayaKhalil_1L

Hybridization allows atomic valence orbitals to be combined. Essentially, it is it necessary for bonding because it decreases the number of paired electrons and increases the number of lone electrons needed to form bonds. For example, take CH4 Normally, C had two, paired electrons in its 2s orbital ...

MayaKhalil_1L

Each atom in the molecule structure should have an octet( excluding the hydrogens). However, the carbons reach their octet by bonding with hydrogen atoms in the molecule, while the rest of the atoms need lone pairs to reach an octet. Both the oxygens, each having only two bonds, need 2 sets of lone ...

MayaKhalil_1L

"Noting that the bond angle of sp^3 hybridized atom is 109.5 degrees and that of an sp^2 hybridized atom is 120 degrees, do you expect the bond angle between two hybrid orbitals to increase or decrease as the s-character of the hybrids in increased?" What do they mean by "s-character ...

MayaKhalil_1L

This is where hybridization comes in. Normally, C only has two unpaired electrons because its 2s orbital is full and its 2p orbital has two unpaired parallel electrons. However, a hybrid of these two orbitals forms 2sp^3 which combines the 2s and 2p orbitals and allows for each of the four electrons...

MayaKhalil_1L

Do you mean number 57? n5=7 because the Balmer series begins at n=2, and since they already gave us four lines, the next line in the series is the fifth. Therefore 2+5= 7. I know its confusing because if you actually count the numbers given it seems like the next line should be n=6, but you need to ...

MayaKhalil_1L

First you want to start off by finding how many mols of potassium ions are in each compound. So for K2S you would multiply: .500g x (1 mol/110.261 g) x (2 mols k+/1 mol K2S)= 9.07 x10^3 The number of moles of K+ is essentially just how many potassium atoms are in the compound. Do the same thing for ...

CHEMISTRY COMMUNITY

Search found 34 matches

Re: Question 5 on the 2013 final

Re: Mechanism Arrow Placement [ENDORSED]

Re: Switching Chem 14C discussion

Practice Problems- Naming

Re: Mechanism Arrow Placement [ENDORSED]

Re: Ambidentate nucleophiles

Re: catalysts

Homework 15.85

Homework 15.79

Re: Calculating Mass remaining after a certain time

Re: Midterm 2016, Question 2

Re: Practice Midterm Winter 2013: Q5B

Re: homework question 14.11

Re: Cell Potentials [ENDORSED]

Re: Spontaneity

Re: Problem 14.5 in the homework

HW 9.85

Re: 8.65

Re: Username

Re: CLOSED vs ISOLATED

Re: ΔH = ΔU Page 20 Confusion

Re: Textbook Q11.93b

Re: Homework problem 4.61

Re: Oxidation Number

Re: Fall Quiz 3 2014

Re: Coordination number

Re: Chapter 4 (Question 61)

Re: Fall 2015 Midterm Q1A

Re: Hybridization

Re: Fall 2015 Practice Midterm

Chapter 4- Question 43

Re: Question About Methane Structure and Carbon Bonding

Re: HW 1.55

Re: Question G21 [ENDORSED]