CHEMISTRY COMMUNITY

Natalie Yakobian

Thanks!

Natalie Yakobian

HI,
I am a little lost on question 5A on where the arrows go for step C -> D. Can someone please explain or show me a picture or their work?
Thank you so much!

Natalie Yakobian

Thanks! However, what if the Trans has both substituents in equatorial position?

Natalie Yakobian

For cyclohexanes in chair postion is Trans always more stable than cis?

Thanks!

Natalie Yakobian

For cyclohexanes in chair postion is Trans always more stable than cis?

Thanks!

Natalie Yakobian

Hi I was wondering in the organic textbook there are more functional groups than we went over in class. Will we be responsible for knowing those as well?

Thanks!

Natalie Yakobian

The Magic of Chem. with Professor Laurence Lavelle (Dr. Wizard L. L.).mp4 [ 24.72 MiB | Viewed 21825 times ]

By:
Dahriel Aron
Natalie Yakobian
Erin Min

Alternate Viewing option through youtube:
https://www.youtube.com/watch?v=W9iU_kyAkCI

Natalie Yakobian

Hi!
Does anyone know some good tricks for identifying how many and what structural isomers we should draw?

Thanks

Natalie Yakobian

Can someone please explain the difference between (E)-1,1-Bromochloropropene and (Z)-1,1,Bromochloropropene . Why are the not both E because the propriety groups are on the same side.

Thanks so much!

Natalie Yakobian

Hi I was wondering if anyone understood what the question from Self Test 1.5B was asking for. It asks us to identify 2-methyl-1,3-butadiene but I don't see any possible structure for that in Limonene. Each molecule seems to only have 1 single bond. What am I doing wrong?

Thanks so much!

Natalie Yakobian

It can also be included before the ene part of the name.

So for 3,6-dimethyl-3-octone where 3 is the the number of the carbon the double bond starts at you can also write it as 3,6-dimethyloct-3-ene.

Natalie Yakobian

Hi
I was wondering for electrophilic aromatic substitution why is the slow step in equilibrium? \

Thanks!

Natalie Yakobian

Hi,
I was wondering from 4.31 in the second step we use intermediates in the rate law. Why is this ok?
Thanks so much.

Natalie Yakobian

Hi I was wondering for the time of rates does time need to be in minutes or can it be in seconds?

Thank you!

Natalie Yakobian

Hi,
I'm confused as to the difference between finding the rate of reaction using the formula 1/a[A]/deltaT or by finding it through rate law formulas like first, second, zero order.

Can someone please explain this?

Thank you!

Natalie Yakobian

Hi, I am confused with question 5B on the 2013 midterm. It asks us to put the following substances in increasing order of standard molar entropy CHF3, CF4, CH3F, CH2F2 I have to conflicting thoughts on this problem. I understand that heavier molecules have higher molar entropy so CF4 would have the ...

Natalie Yakobian

Hi, I was wondering when your balancing chemical equations for Delta Gr are there any rules like there are for Gf, or delta Hf, where you must have only one mol of product so reactant coefficients may need to be in fraction form? For example in one of the past midterms (2012 question 6A) the reactan...

Natalie Yakobian

What is the importance of saying that it is the maximum amount of potential or work being done?

Natalie Yakobian

Hi, For the past quiz numbr 9: A sample of 1 mol of gas initially at 1 atm and 298 K is heated at constant pressure to 350 K then the gas is compressed isothermally to its initial volume and finally it is cooled to 298 K at constant volume. I understand why Delta G and Delta S of system are 0 becaus...

Natalie Yakobian

Hi I am having trouble with HW 9.25 "If SO2F2 adopts a positionally disordered arrangement in its crystal form, what might its residual molar entropy be?" How do we determine the possible number of positions? Also whenever it says molar entropy do we always use avogadro's number? Thanks so...

Natalie Yakobian

HI I was wondering, In the book for changing temperature the only formula given to calculate it was deltaS = Cln(T2/T1) , But in the solution manual for question number 9.13 they use the formula DeltaS =nRln(T2/T1). Wouldn't we instead use Cv = 3/2R and then plug that into the first equation? Thank ...

Natalie Yakobian

When is change in internal energy 0? Is it it only when it says that it's isothermal?

Thank You

Natalie Yakobian

Hi
I was wondering if someone could explain Irreversible vs Reversible processes?

Thanks!

Natalie Yakobian

Hi,
I noticed in the book and on one of the homework questions (8.77) they mention Kekule structures but this is not in our course reader. Will we need to know this for the quiz and exam? Also would someone mind explaining to me what exactly they are?

Thank you!

Natalie Yakobian

Hi I am very confused with question 8.49 Oxygen dif uoride is a colorless, very poisonous gas that reacts rapidly with water vapor to produce O2, HF, and heat. What is the change in internal energy for the reaction of 1.00 mol OF2? I know that deltaU = DeltaH - deltanxRxT, and that delta n is 1 base...

Natalie Yakobian

Hi,
For Gas molecules at

Constant Pressure the Heat Capacity can be found by the formula (5/2)R

Constant Volume the Heat Capacity can be found by the formula (3/2)R

We use this to get the Cm in this problem so then we can find q = nxCmxdeltaT

Hope this helps

Natalie Yakobian

Hi, I was wondering how to solve homework question 8.25. "A constant-volume calorimeter was calibrated by carrying out a reaction known to release 3.50 kJ of heat in 0.200 L of solution in the calorimeter (q= -3.50 kJ), resulting in a temperature rise of 7.32 C. In a subsequent experiment, 100....

Natalie Yakobian

Hi, I was wondering if you have a really large negative change in interal energy and a smaller negative change in internal energy which one would be considered greater? It seems to me that the negative sign just tells us whether energy is used or gained so the negative sign doesn't matter in terms o...

Natalie Yakobian

Why is the percentage deprotonation of benzoic acid in a benzoic acid solution decreased when hydrochloric acid?

Wouldn't the H30+ interact with the conjugate base of benzoic acid?

Thank you!

Natalie Yakobian

HI,
I was wondering how do you know that it should be thought of as a titration problem?

Natalie Yakobian

Hello,
How do you tell if something is a congugagte base/acid?

For example CH3NH3Cl. How would I know that this is the conjugate acid of CH3NH2?
Would I just imagine the Cl dissociating and then realize that CH3NH2?

Thanks!!

Natalie Yakobian

Hi,
I was wondering when calculating pOH and pH do we consider sig figs?

It seems from the book questions that they don't.

Thanks so much!

Natalie Yakobian

HI,
If you are given a reaction and asked if it is a acid/base reaction do you have to take into account whether or not the chemical compounds are soluble? Should we memorize solubility rules?

For example question 12.9 asks us to write the net ionic equations.

Natalie Yakobian

Hi I was wondering do we count the number of sig in K?

For example in problem 11.117 K has two sig figs but the final answer has 3. Why is this?

Natalie Yakobian

Hi, When were dealing with a Equilibrium Constant problem where all products and reactants are gas do we have to first convert to partial pressure and then solve it, or are we allowed to convert to molarity to solve it? For example in the book Example 11.8 we are given grams of gas and a volume. The...

Natalie Yakobian

The following flasks show the dissociation of a diatomic molecule, X2, over time. (a) Which flask represents the point in time at which the reaction has reached equilibrium?(b) What percentage of the X2 molecules have decomposed at equilibrium? (c) Assuming that the initial pressure of X2 was 0.10 ...

Natalie Yakobian

Why would the lone pair of electrons not make everything <90 ?
Thanks so much!

Natalie Yakobian

Hello,
I was wondering if the bond angle square pyramidal is 180, 90 or if it is slightly less than 180, 90.

Thanks so much!

Natalie Yakobian

For C2H4 a Carbon Carbon double bond why is the sigma bond (C2sp^3,C2sp^3) and the Pi bond (C2P, C2P)?

Natalie Yakobian

Thank you! Is this always the case with a central atom? If its in the middle does and has a double bond with one molecule and a single bond with another does it take on the value of a double bond?

Natalie Yakobian

bellow are ball and stick models of two molecules, in each case, indicate where there must be, may be, or cannot be one or more lone pairs of electrons on the central atom The picture is of a trigonal planar molecule with 120 degrees between it and then a linear molecule with 180 degrees But if the...

Natalie Yakobian

Use the information in Fig. 3.21 to estimate the bond length of (a) the CO bond in CO2; (b) the CO and CN bonds in urea, OC(NH2)2; (c) the OCl bond in HClO; (d) the NCl bond in NOCl. Hi, There was a similar question on this about how to solve these. However the post said that the answer to b would ...

Natalie Yakobian

Hi,
I was wondering if someone could please explain the concept of a partial double bond?
Thanks so much.

Natalie Yakobian

Hi I'm a little unclear on what Zeff is. Can someone please explain it to me?

Thanks

Natalie Yakobian

In the ultraviolet spectrum of atomic hydrogen, a line is observed at 102.6 nm. Determine the values of n for the initial and final energy levels of the electron during the emission of energy that leads to this spectral line. For this question I was able to find the two energy level by trail and er...

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