Search found 25 matches

by Jana Sandhu 3J
Tue Mar 08, 2016 10:38 pm
Forum: *Cyclohexanes (Chair, Boat, Geometric Isomers)
Topic: cis conformation
Replies: 2
Views: 387

Re: cis conformation

Page 115 in the course reader answers this if you're asking about a chair conformation!
by Jana Sandhu 3J
Tue Mar 08, 2016 10:26 pm
Forum: *Cyclohexanes (Chair, Boat, Geometric Isomers)
Topic: Boat Conformation Hydrogens
Replies: 1
Views: 294

Re: Boat Conformation Hydrogens

I believe it's referring to the bottom four hydrogens but I'm not sure
by Jana Sandhu 3J
Mon Feb 29, 2016 11:51 pm
Forum: *Organic Reaction Mechanisms in General
Topic: 4.25 charge difference?
Replies: 1
Views: 282

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...
by Jana Sandhu 3J
Sun Feb 21, 2016 9:07 pm
Forum: Zero Order Reactions
Topic: Zero order
Replies: 5
Views: 799

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.
by Jana Sandhu 3J
Thu Feb 18, 2016 10:38 am
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Pre-equilibrium vs steady-state
Replies: 2
Views: 866

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.
by Jana Sandhu 3J
Sun Feb 14, 2016 8:58 pm
Forum: General Rate Laws
Topic: Units for reaction rates
Replies: 1
Views: 298

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.
by Jana Sandhu 3J
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: 291

Notation of cell diagrams

How do we know when to use a comma versus the vertical line in a cell diagram?
by Jana Sandhu 3J
Sat Feb 06, 2016 2:02 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: anode and cathode
Replies: 1
Views: 215

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 ...
by Jana Sandhu 3J
Tue Feb 02, 2016 12:37 am
Forum: Balancing Redox Reactions
Topic: example 14.1
Replies: 1
Views: 310

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...
by Jana Sandhu 3J
Sun Jan 31, 2016 5:43 pm
Forum: Balancing Redox Reactions
Topic: Coulomb
Replies: 4
Views: 657

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
by Jana Sandhu 3J
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: 677

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.
by Jana Sandhu 3J
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: 413

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.
by Jana Sandhu 3J
Sun Jan 17, 2016 11:40 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Homework 8.31
Replies: 4
Views: 563

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?
by Jana Sandhu 3J
Mon Jan 11, 2016 11:07 am
Forum: Phase Changes & Related Calculations
Topic: Phase Changes- Melting/Boiling
Replies: 4
Views: 601

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.
by Jana Sandhu 3J
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: 325

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 ...
by Jana Sandhu 3J
Mon Nov 30, 2015 4:47 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 8046
Views: 1412593

Re: Chemistry Jokes

A neutron walks into a bar.
Before leaving, he asks the bartender, "How much?"
The bartender responds, "No charge."
by Jana Sandhu 3J
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: 629

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 ...
by Jana Sandhu 3J
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: 484

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...
by Jana Sandhu 3J
Thu Nov 12, 2015 10:00 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Relationship between K and Q
Replies: 3
Views: 508

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 ...
by Jana Sandhu 3J
Thu Nov 05, 2015 4:50 pm
Forum: Hybridization
Topic: Unpaired electrons
Replies: 2
Views: 380

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.
by Jana Sandhu 3J
Thu Oct 29, 2015 10:27 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: formal charge
Replies: 3
Views: 486

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...
by Jana Sandhu 3J
Fri Oct 23, 2015 1:09 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Polar Bonds
Replies: 2
Views: 425

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...
by Jana Sandhu 3J
Fri Oct 16, 2015 11:13 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Resonance Structures and VSEPR
Replies: 1
Views: 345

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).
by Jana Sandhu 3J
Thu Oct 08, 2015 3:35 pm
Forum: Properties of Light
Topic: Wavelength Problem
Replies: 1
Views: 403

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...
by Jana Sandhu 3J
Thu Oct 01, 2015 8:59 pm
Forum: Significant Figures
Topic: Basic Rules for Sig Figs
Replies: 3
Views: 603

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...

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