Search found 26 matches

by Alli Foreman 2H
Sat Mar 12, 2016 12:03 am
Forum: *Organic Reaction Mechanisms in General
Topic: Drawing and labeling reaction profile
Replies: 3
Views: 656

Re: Drawing and labeling reaction profile

\Delta G\neq ^{\circ} is always positive. It is the difference between the \Delta G of the reactants and the \Delta G of the intermediates. \Delta G intermediates is always above \Delta G reactants (think of the graph, it's always a hill shape). So \Delta G of the intermediates - \Delta G of the re...
by Alli Foreman 2H
Fri Mar 11, 2016 11:02 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: winter 2011 midterm, question 2B
Replies: 1
Views: 317

Re: winter 2011 midterm, question 2B

Each of the containers has the same number of moles of atoms. Since container A is a monoatomic gas, it has 1 mole of atoms running around and hitting each other. Container B is made up of diatomic molecules. This means that there are the same number of total atoms (1 mol), but since they are bound ...
by Alli Foreman 2H
Fri Mar 11, 2016 10:56 pm
Forum: *Alcohols
Topic: 2013 Final 5B, page 206
Replies: 2
Views: 485

Re: 2013 Final 5B, page 206

The term (Z) is used because of the difference in atomic numbers on each side of the double bond. In this case, I has a larger atomic number than C (53>6). On the other side of the double bond, C has a larger atomic number than H (6>1). Now you compare the two components with the largest atomic numb...
by Alli Foreman 2H
Fri Mar 11, 2016 10:51 pm
Forum: *Amines
Topic: Primary, secondary, tertiary
Replies: 2
Views: 863

Re: Primary, secondary, tertiary

If the question is asking you to name what type of functional group then yes. In the 2013 final exam #5A, points were taken off if you just said "amine" instead of "secondary amine"
by Alli Foreman 2H
Fri Mar 11, 2016 10:48 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: 2013 question 3
Replies: 2
Views: 428

Re: 2013 question 3

pH=-log[H+] So if you're given the pH you divide by -1 (so that the negative is on the opposite side) and then you raise both sides to 10. This cancels out the log and leaves you with a value of [H+] In this case, 2=-log[H+] so you would say -2=log[H+]. Then 10^(-2)=10^(log[H+]). This leaves you wit...
by Alli Foreman 2H
Tue Mar 01, 2016 4:29 pm
Forum: *Nucleophiles
Topic: Identifying
Replies: 2
Views: 466

Re: Identifying

F would be an electrophile because it is seeking another electron to complete its outer shell. As it is in the second column from the right on the periodic table, it has 7 electrons in its outer shell. Remember that atoms always want to have a full outer shell.
by Alli Foreman 2H
Tue Mar 01, 2016 4:27 pm
Forum: *Complex Reaction Coordinate Diagrams
Topic: Reaction Profile Delta G
Replies: 4
Views: 1165

Re: Reaction Profile Delta G

Does that mean that the graph on the top of page 157 in the orange book is incorrect?
by Alli Foreman 2H
Thu Feb 25, 2016 10:19 pm
Forum: *Organic Reaction Mechanisms in General
Topic: Drawing and labeling reaction profile
Replies: 3
Views: 656

Re: Drawing and labeling reaction profile

\Delta G_{r} is equal to \Delta G_{products} - \Delta G_{reactants}. If the graph's final point is below the initial point, then that means that \Delta G_{products} < \Delta G_{reactants} and therefore \Delta G_{r} will be negative. If the graph's final point is above the initial point, then that m...
by Alli Foreman 2H
Wed Feb 17, 2016 12:05 am
Forum: General Rate Laws
Topic: Units for K
Replies: 1
Views: 376

Re: Units for K

In each case, rate=k*[A]^n. As you said, the units for rate is always moles/(L*sec). The difference between first, second, and zero order reactions is the value of the n. In a first order reaction, n=1. This means that the units for molarity are only to the first power. So if rate=k*[A] that means t...
by Alli Foreman 2H
Wed Feb 10, 2016 11:26 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Potential Increase/Decrease
Replies: 2
Views: 368

Re: Cell Potential Increase/Decrease

Voltage won't be affected by the size of the electrode since it depends on the chemistry of the electrodes, rather than the size.
by Alli Foreman 2H
Sat Feb 06, 2016 12:37 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Monatomic vs Diatomic
Replies: 1
Views: 407

Re: Monatomic vs Diatomic

If you have H2 you only have one molecule. However, if you have 2H you have two molecules (while still having the same number of H atoms). 2H has greater entropy because it has more molecules and therefore greater disorder.
by Alli Foreman 2H
Sun Jan 31, 2016 11:34 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Half Reactions
Replies: 1
Views: 265

Re: Half Reactions

You reverse whichever E will make the final EMF positive because that's what makes a reaction spontaneous (which is always favored).
by Alli Foreman 2H
Sun Jan 24, 2016 11:18 am
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Homework Problem 9.19
Replies: 1
Views: 376

Re: Homework Problem 9.19

The problem is asking for us to find the entropy of vaporization of water at 85 degrees Celsius. However, we know that water will not vaporize until it reaches 100 degrees Celsius. So we have to first heat it up to 100 degrees, then carry out the phase change, and then cool the product back to 85 de...
by Alli Foreman 2H
Sat Jan 16, 2016 1:22 pm
Forum: Calculating Work of Expansion
Topic: Reversible expansion
Replies: 3
Views: 953

Re: Reversible expansion

You get more work out of a process when it is done slowly because less heat is lost to the surroundings. Since a reversible process is done infinitely slowly, you lose the least possible amount of work. Therefore a reversible process does the maximum work.
by Alli Foreman 2H
Sun Jan 10, 2016 1:31 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Bond Enthalpies
Replies: 1
Views: 295

Re: Bond Enthalpies

You can determine the number of bonds in the reaction by drawing out the Lewis structures of each of the reactants and products and then counting up the total number of bonds. Remember to account for formal charge when choosing the most likely bond formation.
by Alli Foreman 2H
Wed Dec 02, 2015 4:27 pm
Forum: Lewis Acids & Bases
Topic: Lewis vs. Bronsted acids/bases
Replies: 5
Views: 3530

Re: Lewis vs. Bronsted acids/bases

The difference between these two definitions has to do with the particle being transferred. Lewis acids are electron acceptors while Bronsted acids are proton donators. Lewis bases are electron donators while Bronsted bases are proton acceptors. In a reaction with a Bronsted acid, the acid would los...
by Alli Foreman 2H
Wed Nov 25, 2015 12:00 am
Forum: Identifying Acidic & Basic Salts
Topic: Why does KBR have a neutral pH?
Replies: 3
Views: 7190

Re: Why does KBR have a neutral pH?

Breaking down KBr would give you K+ and Br-. K+ is weak. Br- is the conjugate base of HBr. Since HBr is a strong acid, Br- would be a weak base. Since both products are weak, there will be no real effect on pH, therefore you can say it's neutral.
by Alli Foreman 2H
Thu Nov 19, 2015 4:26 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: Strong Acid or Weak Acid?
Replies: 2
Views: 459

Re: Strong Acid or Weak Acid?

A strong acid is one that completely ionizes in a solution. When hydrogen chloride gas dissolves in water, the hydrogen chloride molecule gives a proton (in the form of a hydrogen ion) to a water molecule. This creates H3O+ as well as Cl-. One mole of HCl should yield one mole of H3O+ and one mole o...
by Alli Foreman 2H
Fri Nov 13, 2015 3:30 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Equilibrium shifting to the right or left
Replies: 1
Views: 563

Re: Equilibrium shifting to the right or left

K is a ratio of concentration of products to concentration of reactants. Note that it's not a ratio of the actual amount of products to reactants. So when K is very small (smaller than 10^-3) that means there is a high concentration of reactants (since they are in the denominator of the K equation)....
by Alli Foreman 2H
Mon Nov 02, 2015 8:59 pm
Forum: Hybridization
Topic: Hybridization Involving Tryptophan
Replies: 1
Views: 994

Re: Hybridization Involving Tryptophan

This structure is drawn differently from those we usually do in that it doesn't show all the hydrogen atoms or all the lone pairs. The problem states this (it's usually done just to save space/time). In this case, N is bonded to two hydrogen atoms, one carbon atom, and then it also has a lone pair t...
by Alli Foreman 2H
Thu Oct 29, 2015 11:01 pm
Forum: Dipole Moments
Topic: Polarity
Replies: 2
Views: 551

Re: Polarity

It's also important to note that the symmetry of a molecule must take into account the lone pairs (if there are any) on the central atom. If there is one lone pair on the top and none on the bottom then the molecule is not symmetrical and therefore polar. Same goes for if there are two lone pairs on...
by Alli Foreman 2H
Fri Oct 23, 2015 11:48 am
Forum: Lewis Structures
Topic: Ch.4 23a), b)
Replies: 1
Views: 291

Re: Ch.4 23a), b)

The answer key does only show single bond Lewis Structures for this question, however at the bottom it notes: "Other acceptable Lewis structures are possible (those with double bonds between the central atom and oxygen, which are more stable structures due to the lowering of formal charge) but ...
by Alli Foreman 2H
Tue Oct 13, 2015 9:23 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Shells & Orbitals
Replies: 3
Views: 633

Re: Shells & Orbitals

Shells and orbitals are not the same. When talking about the notation of an element:
n refers to the shell; n = 1, 2, 3, 4, ...
l refers to the subshell; l = n-1 so 0, 1, 2, 3, ...
ml refers to the orbital; ml = -l through +l
ms refers to the spin state; ms = -1/2 or +1/2
by Alli Foreman 2H
Wed Oct 07, 2015 4:05 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Infrared Spectroscopy
Replies: 1
Views: 388

Re: Infrared Spectroscopy

Since c= \lambda \nu you can say that \lambda = c/\nu . However, since you have cm^{-1} you simply take the reciprocal of the equation: 1/\lambda = \nu /c Once you have the equation set up, you can plug in the wavelength you are given. You will need to convert it from centimeters to meters. Then you...
by Alli Foreman 2H
Wed Sep 30, 2015 11:18 pm
Forum: Photoelectric Effect
Topic: Photoelectric Effect Process
Replies: 3
Views: 487

Re: Photoelectric Effect Process

A photon is just a packet of energy, it does not have a mass or an electric charge (very different from a proton, although the two sound similar). When the photon's energy matches that of the difference between energy levels, the energy is transferred to the electron. Since a photon is simply energy...

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