Search found 25 matches
- Tue Mar 08, 2016 10:38 pm
- Forum: *Cyclohexanes (Chair, Boat, Geometric Isomers)
- Topic: cis conformation
- Replies: 2
- Views: 588
Re: cis conformation
Page 115 in the course reader answers this if you're asking about a chair conformation!
- Tue Mar 08, 2016 10:26 pm
- Forum: *Cyclohexanes (Chair, Boat, Geometric Isomers)
- Topic: Boat Conformation Hydrogens
- Replies: 1
- Views: 432
Re: Boat Conformation Hydrogens
I believe it's referring to the bottom four hydrogens but I'm not sure
- Mon Feb 29, 2016 11:51 pm
- Forum: *Organic Reaction Mechanisms in General
- Topic: 4.25 charge difference?
- Replies: 1
- Views: 385
4.25 charge difference?
On question 4.25, one of the species involved is Br2. The solution shows that there is an electronegativity difference between the two bromine molecules, saying one is more negative and the other more positive. Why is this so considering it is the same element bonded to itself? Shouldn't there be no...
- Sun Feb 21, 2016 9:07 pm
- Forum: Zero Order Reactions
- Topic: Zero order
- Replies: 5
- Views: 1228
Re: Zero order
The rate law for a zero order reaction is rate=k. Can also be written as rate=k[A]^0 to more plainly see that it is zero. From this you can tell that the concentration of the reactant will have no affect on the rate of the reaction, as it is solely dependent on the rate constant k.
- Thu Feb 18, 2016 10:38 am
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Pre-equilibrium vs steady-state
- Replies: 2
- Views: 1165
Re: Pre-equilibrium vs steady-state
In lecture Dr. Lavelle said to just use the pre-equilibrium method rather than the steady-state one. He purposely only assigned textbook problems that use pre-equilibrium instead of steady-state.
- Sun Feb 14, 2016 8:58 pm
- Forum: General Rate Laws
- Topic: Units for reaction rates
- Replies: 1
- Views: 415
Re: Units for reaction rates
Judging from past expectations from Dr. Lavelle, I would assume it doesn't matter unless the answer corresponds to sig figs and has accurate units. As in look at sig figs first and adjust units accordingly.
- Sat Feb 06, 2016 2:05 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Notation of cell diagrams
- Replies: 1
- Views: 414
Notation of cell diagrams
How do we know when to use a comma versus the vertical line in a cell diagram?
- Sat Feb 06, 2016 2:02 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: anode and cathode
- Replies: 1
- Views: 363
Re: anode and cathode
The values stated in the table are reduction potentials, so if you have two different pairs of species and are trying to decide which pair undergoes reduction and which undergoes oxidation, the one with the higher reduction potential is the one more likely to be reduced. Therefore the other species ...
- Tue Feb 02, 2016 12:37 am
- Forum: Balancing Redox Reactions
- Topic: example 14.1
- Replies: 1
- Views: 445
Re: example 14.1
The molecule is C2H2O4. We know H is almost always +1, and O is almost always -2. The overall charge of the compound is 0. For hydrogen, 2x1 is +2, and for oxygen, 4x(-2) is -8. Adding these together gives -6. So we know that the total charge of the carbons must be +6 for the molecule's charge to eq...
- Sun Jan 31, 2016 5:43 pm
- Forum: Balancing Redox Reactions
- Topic: Coulomb
- Replies: 4
- Views: 932
Re: Coulomb
I don't think it's written anywhere in the course reader, but Dr. Lavelle said one coulomb is equivalent to the charge of 10^18 electrons
- Sun Jan 24, 2016 4:29 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Homework Question 8.49 - Why can you not use a mole ratio?
- Replies: 4
- Views: 1002
Re: Homework Question 8.49 - Why can you not use a mole rati
Whenever temperature is not given in a situation where it is needed for calculations, always assume it is 298K (25 degrees Celcius) because that is part of standard conditions.
- Sun Jan 24, 2016 4:24 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Hess's Law
- Replies: 3
- Views: 581
Re: Hess's Law
Remember when you multiply all the coefficients by a common number, that common number doesn't necessarily have to be or yield whole numbers. They could result in improper fractions as well.
- Sun Jan 17, 2016 11:40 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Homework 8.31
- Replies: 4
- Views: 770
Re: Homework 8.31
The solutions manual includes 20.8 J*mol^-1*C^-1 in the calculation for this solution; where does this value come from?
- Mon Jan 11, 2016 11:07 am
- Forum: Phase Changes & Related Calculations
- Topic: Phase Changes- Melting/Boiling
- Replies: 4
- Views: 867
Re: Phase Changes- Melting/Boiling
Usually the constant controlled temperature of the system can be explained by the setup of the experiment, which is not always mentioned. For example, Dr. Lavelle mentioned an experiment that could occur underwater in water of a uniform temperature, or in a closed system such as a calorimeter.
- Tue Dec 01, 2015 8:13 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: Ka/Kb values not listed
- Replies: 1
- Views: 482
Ka/Kb values not listed
Hello, For problems 65 through 73 on the Chapter 12 homework, we are given initial concentrations (or information to find initial concentrations) of acids and bases and are asked to find their pH. However, their K values do not appear in tables 12.1 and 12.2. Do we need to look them up ourselves or ...
- Mon Nov 30, 2015 4:47 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3009136
Re: Chemistry Jokes
A neutron walks into a bar.
Before leaving, he asks the bartender, "How much?"
The bartender responds, "No charge."
Before leaving, he asks the bartender, "How much?"
The bartender responds, "No charge."
- Sun Nov 29, 2015 9:15 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Pressure aspect of Le Chatelier's Principle
- Replies: 2
- Views: 858
Re: Pressure aspect of Le Chatelier's Principle
Change in pressure is driven by a change in volume because from the ideal gas law, we can see that P=(nRT)/V. Thus, a change in volume always results in a change in pressure. The change in pressure will never simply be a change in pressure in itself because that would mean calculating the increased ...
- Fri Nov 20, 2015 5:05 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Adding Water
- Replies: 2
- Views: 704
Re: Adding Water
Hi! Adding water could reduce concentration because there would be the same amount of moles of a substance but in a larger volume of solution. However it all depends on the problem, and usually information will be given that would allow you to determine the new initial concentrations to put into the...
- Thu Nov 12, 2015 10:00 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Relationship between K and Q
- Replies: 3
- Views: 746
Re: Relationship between K and Q
You are correct about K and Q being calculated in the same way. From what I've been seeing, in questions involving Q, K is usually given and you are asked to find Q in order to determine whether or not the reaction is at equilibrium and in what way the reaction will occur to approach equilibrium. I ...
- Thu Nov 05, 2015 4:50 pm
- Forum: Hybridization
- Topic: Unpaired electrons
- Replies: 2
- Views: 527
Re: Unpaired electrons
I believe that even an unpaired electron would still count as a region of electron density, so it would be included in hybridization. But we're rarely asked anything about radicals so I wouldn't worry about it too much.
- Thu Oct 29, 2015 10:27 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: formal charge
- Replies: 3
- Views: 662
Re: formal charge
^The above scenario is something I've never heard of or encountered so I can't give a definite answer for that. However, if two different resonance structures both yield an overall formal charge of 0, the more stable one is one in which more individual atoms have a charge of 0, so if one structure y...
- Fri Oct 23, 2015 1:09 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Polar Bonds
- Replies: 2
- Views: 578
Re: Polar Bonds
^The above procedure determines if the molecule as a whole is polar or not. To answer your question about determining if an individual bond is polar, you have to look at the electronegativity of each element in the bond. If there is a difference in electronegativity, there is a "dipole moment&q...
- Fri Oct 16, 2015 11:13 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Resonance Structures and VSEPR
- Replies: 1
- Views: 513
Re: Resonance Structures and VSEPR
Resonance structure is reflected in VSEPR in that the double/triple bonds appear shorter than single bonds (shorter lines in the drawings).
- Thu Oct 08, 2015 3:35 pm
- Forum: Properties of Light
- Topic: Wavelength Problem
- Replies: 1
- Views: 592
Re: Wavelength Problem
So I see that this problem is from the 5th edition book, which doesn't really correspond much to the 6th edition as far as homework problems go. To solve this you would first use Rydberg's equation: Frequency= Z^2 * R(1/(n initial squared) - 1/(n final squared)) Once you determine the frequency from...
- Thu Oct 01, 2015 8:59 pm
- Forum: Significant Figures
- Topic: Basic Rules for Sig Figs
- Replies: 3
- Views: 793
Re: Basic Rules for Sig Figs
-Zeros that are only used to set a decimal point are NOT significant (e.g. 0.0005 has 1 sig fig, as does 2000) -Zeros in between two integers ARE significant (e.g. 6067 has 4 sig figs) -Zeros trailing after a decimal ARE significant (e.g. 6067.300 has 7 sig figs) -100 has 1 sig fig, but 100. has 3 s...