Search found 62 matches
- Fri Mar 11, 2016 12:49 am
- Forum: Administrative Questions and Class Announcements
- Topic: Class Tomorrow?
- Replies: 1
- Views: 675
Re: Class Tomorrow?
Nope no class tommorow! Dr.Lavelle is still going to have a review session from like 4:30- 6:00 in CS50!
- Wed Mar 09, 2016 11:46 pm
- Forum: *Ketones
- Topic: the prefix un
- Replies: 1
- Views: 1273
Re: the prefix un
the prefix just indicates 1,I think since decane is 10 meaning that undecane stands for an Alkane that has 11 carbons.
- Wed Mar 09, 2016 11:41 pm
- Forum: *Ethers
- Topic: Priority in naming ethers
- Replies: 2
- Views: 568
Re: Priority in naming ethers
I think that ethers may not be given as much priority as the other functional groups simply because they are a part of the substituents name.
- Wed Mar 09, 2016 11:35 pm
- Forum: *Cyclohexanes (Chair, Boat, Geometric Isomers)
- Topic: cis and tran
- Replies: 1
- Views: 349
Re: cis and tran
Yes the chair conformation is the most stable structure a cyclohexane can be no matter if it's a cis or trans structure.
- Wed Mar 02, 2016 7:34 pm
- Forum: *Electrophilic Addition
- Topic: Intermediates
- Replies: 1
- Views: 403
Re: Intermediates
I believe its asking for the molecules involved in the intermediate step.
- Wed Mar 02, 2016 7:31 pm
- Forum: *Electrophilic Addition
- Topic: quiz 3 prep 1 #9 bromomethane+hydroxide
- Replies: 1
- Views: 398
Re: quiz 3 prep 1 #9 bromomethane+hydroxide
I think because its bimolecular, and OH- is a nucleophile, so when the reaction occurs, the other nucleophile that is present, the bromine is kicked out and its there in its place hence SN2
http://static.wikidoc.org/f/f9/BromoethaneSN2reaction-small.png
http://static.wikidoc.org/f/f9/BromoethaneSN2reaction-small.png
Re: ambident
An ambident nucleophile has an atom on it that has lone pairs which it means its a source of electrons. This atom lets the nucleophile act as the source of electrons through it. Thus it is called an ambident nucleophile.
- Wed Feb 24, 2016 8:52 pm
- Forum: *Cycloalkanes
- Topic: naming compounds
- Replies: 1
- Views: 559
Re: naming compounds
They capitalized the B because its the first one in the name of the compound. Think of it like a sentence, you always capitalize the first letter. Likewise in the name you capitalize the first letter of the "sentence" (AKA compound). Notice you don't capitalize prefixes. IF the compound wa...
- Wed Feb 24, 2016 8:46 pm
- Forum: *Alkanes
- Topic: Course reader questions
- Replies: 1
- Views: 375
Re: Course reader questions
I think pentyl is the IUPAC name while amyl is like a common name that you can use whenever. "Alpha" order just stands for alphabetical order.
- Fri Feb 19, 2016 12:07 am
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: Favorable Reactions
- Replies: 2
- Views: 2789
Re: Favorable Reactions
Do you mean kinetically favorable? if so yes there is a difference between thermodynamically favorable and kinetically favorable. Kinetically favorable means that the there is a large difference for activation energy so more products than reactants. Thermodynamically favorable means that there is a ...
- Thu Feb 18, 2016 11:59 pm
- Forum: *Organic Reaction Mechanisms in General
- Topic: CourseReader Example: chloromethane to carbonyl
- Replies: 1
- Views: 366
Re: CourseReader Example: chloromethane to carbonyl
I think those might be two different reactions.
- Thu Feb 18, 2016 10:35 am
- Forum: First Order Reactions
- Topic: Half Life
- Replies: 1
- Views: 436
Re: Half Life
The concentration is independent because if you write out the integral law of of a first order reaction and you figure out the half life equation. You can see that the [A] knot will cancel and your left with ln (1/2)= -kt. Then solving for t gives .693/k. Since the Concentrations canceled out we see...
- Fri Feb 12, 2016 6:38 pm
- Forum: General Rate Laws
- Topic: Unique rate
- Replies: 1
- Views: 402
Re: Unique rate
I think it was, that all the the reactants and products have different reaction rates. What rate you get depends on what you chose. I found this formula that can that gets the average Unique rate:
rate of reaction = (−1/a)(Δ[A]/Δt)=(−1/b)(Δ[B]/Δt)=(1/c)(Δ[C]/Δt)=(1/d)(Δ[D]/Δt)
rate of reaction = (−1/a)(Δ[A]/Δt)=(−1/b)(Δ[B]/Δt)=(1/c)(Δ[C]/Δt)=(1/d)(Δ[D]/Δt)
- Wed Feb 10, 2016 11:06 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: Kinetics
- Replies: 2
- Views: 612
Re: Kinetics
The reaction rate will depend on the only on the smallest reactant. The other two reactants will be in excess so they just remain constants in essence.
- Wed Feb 10, 2016 10:51 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Cell Potential Increase/Decrease
- Replies: 2
- Views: 395
Cell Potential Increase/Decrease
Is the cell potential effected by the size of the anode/cathode electrode? If so why?
- Wed Feb 03, 2016 3:58 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Energy Created by Molecule Movement
- Replies: 1
- Views: 372
Re: Energy Created by Molecule Movement
Yes they do. The energy levels of atoms will give them the ability to vibrate and rotate. This disorder in movement is what gives it it's entropy.
- Wed Feb 03, 2016 3:50 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Most strongly reducing/oxidizing
- Replies: 1
- Views: 364
Re: Most strongly reducing/oxidizing
The more negative the potential is the more electron donating power they have. That means those elements are strong reducing agents because they have the ability to reduce other compounds since they don't want the electrons themselves. They have potential to let the negative charge go. The elements ...
- Wed Jan 27, 2016 9:23 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Class Diagram
- Replies: 1
- Views: 319
Re: Class Diagram
I think its just a convention to put the anode to the left and the cathode to the right since the electrons always from the anode to the cathode. It seems more logical.
- Wed Jan 27, 2016 9:15 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Delta V
- Replies: 2
- Views: 1268
Re: Delta V
In an isolated system nothing can exchange with the surroundings. If nothing can interact then nothing in the system will change. Therefore, the delta V in an isolated system=0 because volume doesn't go up or down its constant.
- Wed Jan 20, 2016 8:49 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: What is "d"?
- Replies: 2
- Views: 421
Re: What is "d"?
I think its supposed to represent changes but the infinitesimal (smaller) changes. On page 36 of the course reader, the equation for the isothermal process for changing temperature to determine entropy has ds , and professor Lavelle said in class that the d was supposed to represent small changes fo...
- Wed Jan 20, 2016 8:39 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Enthalpy and Entropy
- Replies: 3
- Views: 590
Re: Enthalpy and Entropy
Enthalpy is the change in heat, the release and absorption. Entropy is the disorder in a system.
It's relationship can be seen in the equation delta G= delta H- T Delta S. This equation represents the change in free energy.
It's relationship can be seen in the equation delta G= delta H- T Delta S. This equation represents the change in free energy.
- Wed Jan 20, 2016 7:56 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: calculating change in entropy
- Replies: 1
- Views: 255
Re: calculating change in entropy
The value of q should be negative if the equation is delta S for a system because the system will be loosing energy since the heat will flow into the surroundings. Meaning the entropy for the system is negative. The surroundings should have a positive entropy. (For an exothermic process at a constan...
- Fri Jan 15, 2016 7:59 pm
- Forum: Calculating Work of Expansion
- Topic: Integrals
- Replies: 2
- Views: 513
Re: Integrals
To calculate the integral you must take the antiderivative {For example, anti derivative of x is (x^2)/2} of the variables on the inside and pull out the constants if you can. Then plug in the values of the bounds you are given.
However, an easier form of the equation for expansion is w=-P delta V
However, an easier form of the equation for expansion is w=-P delta V
- Wed Jan 13, 2016 8:55 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Thermodynamics vs thermochemistry
- Replies: 1
- Views: 381
Re: Thermodynamics vs thermochemistry
According to the course reader, thermochemistry is "the study of heat released or absorbed in chemical reactions and physical changes"
While thermodynamics is more about the relationship of heat, work, etc.
While thermodynamics is more about the relationship of heat, work, etc.
- Wed Jan 13, 2016 8:48 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Work
- Replies: 4
- Views: 771
Re: Work
There is a negative sign because whenever a system does work it loses energy because its pushing against the pressure. Having a positive sign means its gaining energy which doesn't make sense.
- Wed Jan 13, 2016 8:31 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: When can we assume standard state?
- Replies: 1
- Views: 262
Re: When can we assume standard state?
I think if it's not specified then we should just assume its 25C.
- Wed Jan 13, 2016 8:27 pm
- Forum: Calculating Work of Expansion
- Topic: Reversible and Irreversible
- Replies: 3
- Views: 622
Re: Reversible and Irreversible
I think we also have to know that Irreversible processes are sudden and big changes.
- Thu Jan 07, 2016 8:37 pm
- Forum: Phase Changes & Related Calculations
- Topic: Enthalpy
- Replies: 4
- Views: 695
Re: Enthalpy
Enthalpy is considered a state function because the value isn't determined by the path to the state. It's figured out by the state that it's in at the present.
- Thu Jan 07, 2016 7:38 pm
- Forum: Phase Changes & Related Calculations
- Topic: q subscript p
- Replies: 2
- Views: 1568
Re: q subscript p
q subscript p, p is for constant pressure. q subscript be is then heat being released and absorbed at constant pressure.
- Wed Jan 06, 2016 7:06 pm
- Forum: Phase Changes & Related Calculations
- Topic: Course Reader Help
- Replies: 2
- Views: 441
Re: Course Reader Help
Those three values are supposed to indicate the 3 bonds that were formed to make that molecule from the reaction of CH2CH2 + HBR. The negative sign on those values is because bonds were formed and that releases heat.
- Wed Jan 06, 2016 5:45 pm
- Forum: Phase Changes & Related Calculations
- Topic: Phase Changes
- Replies: 2
- Views: 433
Re: Phase Changes
http://crescentok.com/staff/jaskew/isr/chemistry/heatcurve.gif"onclick="window.open(this.href);return false; If you take a look at the picture you will be able to see that water has to have a lot of heat added and the temperature has to be high for a phase change to occur to steam. The line leading ...
- Wed Jan 06, 2016 5:28 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Enthalpies for State Changes
- Replies: 3
- Views: 516
Re: Enthalpies for State Changes
One equation where you can see them acting together is that of the enthalpy of sublimation where
the delta H of Fusion and delta H vaporization added together can give you the delta H of sublimation.
the delta H of Fusion and delta H vaporization added together can give you the delta H of sublimation.
- Thu Dec 03, 2015 9:59 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: quantum numbers: m [ENDORSED]
- Replies: 3
- Views: 878
Re: quantum numbers: m [ENDORSED]
The l value depends on which orbital gets filled last or the higher energy orbital the outer valence electrons occupy. Technically for Fe, the d orbital gets filled last even though it's placed before 4s^2 because its a higher energy orbital thus giving it the l number of 2 (s=0, l=1, d=2, f=3). m t...
- Thu Dec 03, 2015 8:58 pm
- Forum: *Making Buffers & Calculating Buffer pH (Henderson-Hasselbalch Equation)
- Topic: Weak Acids/Bases
- Replies: 2
- Views: 438
Re: Weak Acids/Bases
Also wouldn't a strong acid and strong cause too big of a change resulting in a very high or low pH which is dangerous for the body?
- Thu Dec 03, 2015 8:56 pm
- Forum: *Making Buffers & Calculating Buffer pH (Henderson-Hasselbalch Equation)
- Topic: Question 13.3-how to solve for hydronium concentration
- Replies: 1
- Views: 407
Re: Question 13.3-how to solve for hydronium concentration
I think both are valid. As long as you are getting the right answer and using correct reasoning it shouldn't matter. However, to be safe I would use the ICE box.
- Thu Dec 03, 2015 8:51 pm
- Forum: Lewis Acids & Bases
- Topic: Trends on the Periodic Table with Acids
- Replies: 2
- Views: 594
Re: Trends on the Periodic Table with Acids
Fluorine is very electronegative so it won't easily give up its electrons which is what a strong acid would do easily. The disassociation energy trend is that that it decreases going to the left and up which can tell you if a certain acid is stronger than another. The lower the disassociation energy...
- Wed Nov 25, 2015 11:13 pm
- Forum: Significant Figures
- Topic: Sig Fig in Equilibrium
- Replies: 2
- Views: 624
Re: Sig Fig in Equilibrium
You can use the values that are given to you like the partial pressure of something or the number of mols of something to figure out how many sig figs you need in your answer along with keeping in mind like Jonathan said to use the least number of sig figs provided.
- Wed Nov 25, 2015 10:52 pm
- Forum: Properties & Structures of Inorganic & Organic Acids
- Topic: HF Acid
- Replies: 3
- Views: 610
Re: HF Acid
I believe it is a weak acid because HF bond is very strong because it has a short bond length. The short bond length is hard to break which makes it hard for it to give up the H+.
- Wed Nov 25, 2015 10:27 pm
- Forum: Ideal Gases
- Topic: When to use atm or bar
- Replies: 2
- Views: 621
Re: When to use atm or bar
I think the sig figs are given by the initial concentration value of H20 which is has 3 sig figs because the zeroes are trailing the 1 in the decimal making them significant.
- Wed Nov 25, 2015 10:09 pm
- Forum: Conjugate Acids & Bases
- Topic: Memorizing types of acids/bases
- Replies: 3
- Views: 831
Re: Memorizing types of acids/bases
Most likely if it is not listed in the course reader then it you probably do not need to know it. The ones in the course reader are the most common ones and important ones that are seen. So don't worry about knowing other acids and bases.
- Fri Nov 20, 2015 8:16 pm
- Forum: Conjugate Acids & Bases
- Topic: Conjugate Acids and Bases
- Replies: 2
- Views: 411
Conjugate Acids and Bases
I don't understand why the conjugate of a strong acid has to be a weak base and visa versa...Why is it like that?
- Fri Nov 20, 2015 7:55 pm
- Forum: Naming
- Topic: -ate ending
- Replies: 2
- Views: 522
Re: -ate ending
If you only look at [CoF6] That has a negative charge hence the adding of at to the end of cobalt because that part is negative. The Potassium is on the outside which is why its not taken into account when deciding if the compound is to have an -ate ending or not.
- Fri Nov 20, 2015 7:52 pm
- Forum: Naming
- Topic: Naming order for formula
- Replies: 1
- Views: 354
Re: Naming order for formula
If you have a ligand that has the same element denoted by itself and in a compound then the one that is denoted by itself comes first. I think the element by itself takes priority over the alphabetical rule.
- Fri Nov 20, 2015 7:41 pm
- Forum: Properties & Structures of Inorganic & Organic Acids
- Topic: Clarification on Acid/Base concepts
- Replies: 2
- Views: 480
Re: Clarification on Acid/Base concepts
Every Bronsted base will be a Lewis base however if you try to apply it the other way it is not always the case.
- Wed Nov 11, 2015 10:41 pm
- Forum: Ideal Gases
- Topic: Homogeneous vs heterogeneous
- Replies: 3
- Views: 782
Re: Homogeneous vs heterogeneous
So if for all the compounds in a reaction it says (g). That means there is only one type of phase meaning its homogenous because the prefix homo- means the same. If in a reaction there is a compound that has the phase (l) and another that has phase (aq) that means that it is heterogenous because the...
- Wed Nov 11, 2015 10:27 pm
- Forum: Naming
- Topic: Naming order
- Replies: 3
- Views: 616
Re: Naming order
Yes that is the way they are supposed to be. The rule is that you put them in alphabetical order. (NH3) is known by the name Amine and H2O is aqua so NH3 would go before H2O according to alphabetical order. Same with NH3 and SO4. NH3 is amine and SO4 is sulfate. A comes before S which means that NH3...
- Wed Nov 11, 2015 10:20 pm
- Forum: Naming
- Topic: names for anionic ligands
- Replies: 2
- Views: 600
Re: names for anionic ligands
I think that we can use both on the quiz it doesn't seem to matter. However normally in class we seem to use the ones that are just under Name*. It doesn't mean that its wrong to use the new IUPAC Name Convention.
- Fri Nov 06, 2015 10:13 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: AX2E3 Shape
- Replies: 7
- Views: 2481
Re: AX2E3 Shape
If you draw them out and place the lone electrons around the central atom you can easily see that AX2E3 , the lone electron pairs distort the shape so that it is linear. Whereas on AX2E2 You can see that the two lone electron pairs distort it so that it is a bent shape. The number of lone electron p...
- Wed Nov 04, 2015 10:21 pm
- Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
- Topic: lone pairs in molecular orbitals
- Replies: 3
- Views: 474
Re: lone pairs in molecular orbitals
I'm pretty sure you have to put it in whichever one comes first in order for it to be right. When you writing the configuration it will be right but on the diagram if you put it in the Pi*2py orbital it would be wrong. Since that isn't the one that would get filled first if you went in order.
- Wed Nov 04, 2015 10:17 pm
- Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
- Topic: Drawing MO Energy Diagrams
- Replies: 3
- Views: 540
Re: Drawing MO Energy Diagrams
It is based off of electronegativity. The more electro negative atom will be pulled "down" while the other atom that is less electronegative gets pushed up.
- Wed Nov 04, 2015 10:13 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Dissociation Energy
- Replies: 2
- Views: 567
Re: Dissociation Energy
I am not sure what the specific equation is but it generally trends on the periodic table by increasing at you go up and to the right of the periodic table.
- Wed Nov 04, 2015 10:07 pm
- Forum: Naming
- Topic: Ligand names
- Replies: 2
- Views: 335
Re: Ligand names
Yes we do have to know all of them.
- Fri Oct 30, 2015 3:38 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Lone Pair Repulsion in Bent Molecules
- Replies: 5
- Views: 1233
Re: Lone Pair Repulsion in Bent Molecules
Emma it would result in a linear shape. Polarity I think would depend on which atoms are attached to the molecule. If the other two attached are the same then it would be non polar. Most likely if it is linear the atom will be non polar.
- Thu Oct 29, 2015 11:01 am
- Forum: Resonance Structures
- Topic: How to determine which element is the "central" element
- Replies: 3
- Views: 3857
Re: How to determine which element is the "central" element
An easy way to pick a central atom is to think how many open spaces it has. For example if you were to pick the central atom for CO2. C has four open spaces because there it needs 4 more electrons to fill its shell. O has 2 open spaces so it only needs two more electrons to fill its shell. Since C h...
- Thu Oct 22, 2015 1:05 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Sigma bonds and Pi Bonds
- Replies: 8
- Views: 1174
Re: Sigma bonds and Pi Bonds
Can you have more than one sigma bond?
- Wed Oct 21, 2015 9:35 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Sigma bonds and Pi Bonds
- Replies: 8
- Views: 1174
Sigma bonds and Pi Bonds
How you determine whether a molecule has more than one sigma bond or pi bond? Or how many of each type to use? I don't understand this concept well...
- Wed Oct 21, 2015 9:02 pm
- Forum: Hybridization
- Topic: S-character
- Replies: 2
- Views: 522
Re: S-character
Which page is this on?
- Wed Oct 14, 2015 9:28 pm
- Forum: Octet Exceptions
- Topic: Hypervalent Compounds
- Replies: 1
- Views: 424
Hypervalent Compounds
Do hypervalent compounds have limitations? If so what are they? Is there a certain group of elements they can't form bonds with while having bonds with other elements?
- Wed Oct 07, 2015 11:55 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Hunds Rule
- Replies: 2
- Views: 384
Hunds Rule
I did not learn Hund's Rule in my chemistry class so I am still confused to as to what it is and how to use it effectively? Can someone give me an example of how to use it and what it is exactly?
- Wed Oct 07, 2015 11:39 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Using Orbital Chart for Electron Configurations
- Replies: 1
- Views: 333
Re: Using Orbital Chart for Electron Configurations
I think it is quite legitimate. I think it is just a method to remember what order to go in. I know that it was useful for me when I used it. Maybe it's different for this class but I'm sure we can still use it if it helps us and we are getting the right results.
- Thu Oct 01, 2015 3:51 pm
- Forum: Einstein Equation
- Topic: The value of Planck's Constant
- Replies: 3
- Views: 1370
The value of Planck's Constant
I don't understand how was the value of Planck's constant derived?
- Thu Oct 01, 2015 1:52 pm
- Forum: Significant Figures
- Topic: Exact numbers in the final answers
- Replies: 4
- Views: 870
Re: Exact numbers in the final answers
No, I should think not. I'm pretty sure we round up whatever answer we get. So if you got 40.07 it would be 40.1 which would be the same as the answer 40.13 if you didn't include the last number 3. I'm not sure but I think this is what we would do.