Search found 21 matches

by Andrew Afyouni
Thu Mar 10, 2016 11:20 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Practice Final 2011, Q1C
Replies: 2
Views: 311

Re: Practice Final 2011, Q1C

greater molar mass, greater heat capacity. Ethane has a molecular formula of CH3CH3 as opposed to ethene's CH2CH2 due to the presence of a double bond. Basically, the more "stuff" there is in a molecule, the more heat capacity that molecule has
by Andrew Afyouni
Mon Mar 07, 2016 11:11 pm
Forum: *Cyclohexanes (Chair, Boat, Geometric Isomers)
Topic: Cis and Trans Isomers?
Replies: 3
Views: 398

Re: Cis and Trans Isomers?

So actually you don't always need a double bond in order to have cis- or trans- conformations of organic molecules. While the molecules that demonstrated cis- and trans- conformations did contain double bonds which contributed to these differences in molecular conformation, cis- and trans- isomers c...
by Andrew Afyouni
Mon Feb 29, 2016 9:44 am
Forum: *Haloalkenes
Topic: (E)-3-Chloro-4-fluoro-7-methyloct-3-en-5-yne
Replies: 3
Views: 742

(E)-3-Chloro-4-fluoro-7-methyloct-3-en-5-yne

Can someone justify their logic in naming (E)-3-Chloro-4-fluoro-7-methyloct-3-en-5-yne? (I have attached a picture to this post from p. 50 of the organic chemistry orange book) My question stems from why the double bond is given the lower carbon # rather than the triple bond...It was my impression t...
by Andrew Afyouni
Fri Feb 26, 2016 12:02 pm
Forum: *Constitutional and Geometric Isomers (cis, Z and trans, E)
Topic: (E)-1,1-bromochloropropene
Replies: 1
Views: 324

(E)-1,1-bromochloropropene

Would 1-bromo-1-chloro-1-propene be another acceptable way of expressing 1,1-bromochloropropene?
by Andrew Afyouni
Wed Feb 24, 2016 1:09 am
Forum: *Alkanes
Topic: IUPAC
Replies: 3
Views: 374

Re: IUPAC

Adding on to the previous post, a good summary of naming organic compounds:

1. You want your substituents (R groups) in alphabetical order
2. You want to achieve the lowest numbers in describing the chemical structure of the organic compound
by Andrew Afyouni
Tue Feb 16, 2016 10:51 am
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Quiz 2 Prep Winter 2014 Q12
Replies: 1
Views: 243

Re: Quiz 2 Prep Winter 2014 Q12

In this problem, do not round off your answer after finding the slope of the linear plot, k. You would keep the answer as 1.3125 and when you go to solve for half life, you would get 0.762 sec
by Andrew Afyouni
Fri Feb 12, 2016 8:41 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Midterm Question of cell potential
Replies: 3
Views: 402

Re: Midterm Question of cell potential

the mass of the electrode is essentially the product or reactant precipitating out of the reaction...in other words, the species precipitating out is in the solid state and does not participate in the reaction quotient, Q. Thus, the mass of the electrode does not affect the electrical potential (E) ...
by Andrew Afyouni
Mon Feb 01, 2016 1:48 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: delta G and Wmax
Replies: 1
Views: 719

delta G and Wmax

In Friday's lecture, Dr. Lavelle mentioned briefly that delta G is equal to Wmax under conditions of constant temperature and pressure. Could someone mention why this is? I know it is based off the concepts mentioned in thermochemistry but I would appreciate a brief refresher. Thanks in advance!
by Andrew Afyouni
Fri Jan 29, 2016 8:00 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Quiz 1 Preparation Question (Gibbs Free Energy?)
Replies: 2
Views: 587

Re: Quiz 1 Preparation Question (Gibbs Free Energy?)

Energy is required to separate intermolecular forces holding bonds together...these bonds include hydrogen bonds, dipole dipole interactions, and London dispersion forces. Adding energy to the system is required to facilitate the breaking of these interactions and thus the heat at constant pressure ...
by Andrew Afyouni
Fri Jan 22, 2016 1:07 am
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Internal Energy and Temperature
Replies: 1
Views: 204

Internal Energy and Temperature

In Wednesday's lecture, Dr. Lavelle mentioned that the change in internal energy is equal to 0 when the change in temperature is 0. Could someone please explain why this is? Thank you!
by Andrew Afyouni
Fri Jan 15, 2016 4:57 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Kelvin and degrees celcius
Replies: 4
Views: 447

Re: Kelvin and degrees celcius

Going off Chem_Mod, Kelvin is often substituted for Celsius in order to derive certain equations and avoid unnecessary negative values. Since all values of Kelvin will be positive, using Kelvin as a standard of measurement avoids those negatives.
by Andrew Afyouni
Fri Jan 08, 2016 1:40 pm
Forum: Phase Changes & Related Calculations
Topic: Definition Enthalpy in relation to q
Replies: 1
Views: 479

Definition Enthalpy in relation to q

Professor Lavelle mentioned that enthalpy (q sub p) is a state function and thus not dependent on the pathway taken. However, simply stating that heat (q) is a state function would be incorrect. I am curious why constant pressure results in heat being labeled as enthalpy and not other conditions imp...
by Andrew Afyouni
Fri Dec 04, 2015 3:01 pm
Forum: Polyprotic Acids & Bases
Topic: finding pH
Replies: 2
Views: 463

Re: finding pH

Professor Lavelle,

Could you address how to use the equation pH= .5(pKa1 +pKa2) and when it is appropriate to use it?

Thanks
by Andrew Afyouni
Fri Nov 20, 2015 5:22 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Approximations with Weak Acids/Bases
Replies: 1
Views: 331

Approximations with Weak Acids/Bases

In lecture, Dr. Lavelle explained that if the concentration of [H30]+ or [OH-] falls below 5% of the initial amount of Weak Acid/Base, the approximation that there will be no significant change to the reactant of the reaction could be used. However, we are only informed if this is the case after we ...
by Andrew Afyouni
Fri Nov 13, 2015 2:05 pm
Forum: Naming
Topic: Finding the charge
Replies: 2
Views: 278

Re: Finding the charge

You know that both amines and aqua(water) ligands have a neutral charge. Therefore, the 3+ charge on the Chromium must come from another species outside the coordination complex. Sulfate Ions have a 2- charge and knowing that there are 2 coordination complexes for every 3 sulfate ions, you know that...
by Andrew Afyouni
Fri Nov 06, 2015 12:34 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: How important is the central atom? Hypothetical question
Replies: 2
Views: 378

Re: How important is the central atom? Hypothetical question

So here is something interesting to consider: The structure of chlorophyll and hemoglobin are identical except for their central atoms. If you place a magnesium atom in the center of the porphyrin ring (the name of the general structure), you end up getting a chlorophyll molecule. If you place an ir...
by Andrew Afyouni
Fri Oct 30, 2015 2:37 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Why are names of a few chemical species reversed in struct?
Replies: 1
Views: 222

Re: Why are names of a few chemical species reversed in stru

The reversed chemical species are to signify which two atoms are participating in bonding. For example, in a bond between Nickel and NH3, you want all the bonds to be between the N and the Ni atom in order to form a coordination complex. When drawing an octahedral arrangement, the structure should r...
by Andrew Afyouni
Thu Oct 22, 2015 9:32 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Dissociation Energies
Replies: 2
Views: 309

Re: Dissociation Energies

Dissociation energy refers to the amount of energy needed to break a bond into its subunit atoms. In order to separate these bonds, energy much be absorbed by the bond. Thus, a positive amount of energy is taken in (absorbed) by the bond which facilitates the breaking of the bond. Dissociation energ...
by Andrew Afyouni
Fri Oct 16, 2015 8:19 am
Forum: Lewis Structures
Topic: Drawing a Lewis Structure with a double/triple bond
Replies: 4
Views: 619

Re: Drawing a Lewis Structure with a double/triple bond

The student above me is absolutely right. The key to this example is not so much focusing on the Oxygen in the molecule but rather the Carbon. You could have 6 electrons around the oxygen, however, you would need to satisfy the octet around the carbon first. Since Carbon would only have three pairs ...
by Andrew Afyouni
Thu Oct 08, 2015 9:06 pm
Forum: Trends in The Periodic Table
Topic: Thorium, Cerium, Lanthanium, and Actinium
Replies: 1
Views: 299

Thorium, Cerium, Lanthanium, and Actinium

I was looking over the election configurations for elements that require electrons in the f orbitals and I stumbled upon 4 elements that had electron configurations I was not expecting. For Thorium, for example, I was expecting the e- configuration to be ([Rn] 4f1 7s2) when in reality it is ([Rn] 6d...
by Andrew Afyouni
Thu Oct 01, 2015 10:27 am
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Determining values of n given the wavelength
Replies: 2
Views: 807

Re: Determining values of n given the wavelength

So you are given a wavelength of 102.6 nm which will need to be converted to 102.6 x 10^-9 m. Using that wavelength, you can find the frequency of the radiation through the equation c=(wavelength)(frequency) where c is the speed of light. Now Dr. Lavelle is in favor of the original equation for Rydb...

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