Search found 23 matches

Wed Mar 15, 2017 3:09 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Winter 2014 Q3
Replies: 4
Views: 562

Re: Winter 2014 Q3

The voltage values would probably be given either on that page of the exam or on a separate sheet of reduction reactions and their respective voltage values.
Sat Mar 11, 2017 1:08 pm
Forum: *Alkynes
Topic: Alkyne Naming
Replies: 1
Views: 1282

Re: Alkyne Naming

We should know that alkynes indicate a carbon triple bond, but (like you said) we should probably focus more on alkanes and alkenes.
Sun Mar 05, 2017 11:26 pm
Forum: Resonance in Organic Compounds
Topic: Prefixes in Alphabetization
Replies: 2
Views: 900

Re: Prefixes in Alphabetization

When alphabetizing, we would take iso- and neo- into account, but not sec- or tert-.
Sun Feb 26, 2017 11:10 am
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Activation Energy
Replies: 3
Views: 583

Re: Activation Energy

The activation energy of an endothermic reaction is greater than that of an exothermic reaction, but you can't determine if a reaction is endothermic or exothermic by looking at the activation energy.
Sun Feb 19, 2017 8:56 pm
Forum: General Rate Laws
Topic: Homework 15.85
Replies: 2
Views: 419

Re: Homework 15.85

You can look on page 70 in the course reader for that.
Sat Feb 11, 2017 11:19 am
Forum: General Science Questions
Topic: Sig Figs: Rounding Off
Replies: 2
Views: 509

Re: Sig Figs: Rounding Off

Fri Feb 03, 2017 9:27 am
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Equation
Replies: 1
Views: 280

Re: Equation

The final volume is V2. I think you got it confused with pressure. For pressure, deltaS=nRln(P1/P2).
Mon Jan 23, 2017 6:46 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Question 8.9
Replies: 1
Views: 301

Re: Question 8.9

First you solve for work (w=-Pextdelta V) to get -1.48 L atm, which you convert to -0.150 kJ. Then you use delta U=q+w. In this case, it would be 5.50 kJ (which is given to us in this problem) + (-0.150 kJ) = 5.35 kJ. Hope this helps!
Tue Jan 17, 2017 2:26 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: relationship between delta H and q [ENDORSED]
Replies: 4
Views: 1952

Re: relationship between delta H and q[ENDORSED]

Delta H is considered a specific type of q. Delta H=qp.
Sat Jan 14, 2017 10:34 pm
Forum: Administrative Questions and Class Announcements
Topic: Workbook quizzes
Replies: 2
Views: 473

Re: Workbook quizzes

Dr. Lavelle said in an earlier post that the reason why we're not turning in workbook quizzes to replace a quiz grade is that there are ~1200 students taking Chem 14B this quarter, so that would be way too many quizzes for his TAs to grade.
Thu Dec 01, 2016 10:59 am
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Heteronuclear Diatomic Molecules
Replies: 2
Views: 449

Re: Heteronuclear Diatomic Molecules

Would we need to know how to draw MO diagrams for heteronuclear diatomic molecules that are not in the same period (i.e. NaF)?
Wed Nov 30, 2016 8:31 pm
Forum: *Titrations & Titration Calculations
Topic: ICE
Replies: 5
Views: 688

Re: ICE

If the k value is equal to 10^-5, would we keep the x in the denominator and use the quadratic equation?
Sun Nov 27, 2016 11:10 pm
Forum: Lewis Acids & Bases
Replies: 1
Views: 424

Boron can break the octet rule. So you could add a lone pair to BF3 (which, by the way, doesn't even follow the octet rule anyway), which is why BF3 is a Lewis acid.
Tue Nov 22, 2016 3:54 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: 11.73 b
Replies: 1
Views: 379

Re: 11.73 b

You would disregard the C(s) because it's a solid. So there's 1 mole on the reactant side and 2 moles on the product side, which is why the reactant side is favored.
Sat Nov 19, 2016 8:10 pm
Forum: Naming
Topic: Polydentates
Replies: 4
Views: 656

Re: Polydentates

I'm pretty sure we will need to know all of the ligands on that one page in the course reader.
Sun Nov 13, 2016 7:48 pm
Forum: Naming
Topic: Quick way to determine oxidation number?
Replies: 1
Views: 1579

Re: Quick way to determine oxidation number?

You look at the formal charges. For example, in [Cr(edta)]-1 the oxidation number for chromium is +3 because the formal charge of edta is -4 and the overall charge is -1, so +3-4=-1.
Sat Nov 05, 2016 12:46 am
Forum: Hybridization
Topic: Regions of Electron Density & Naming Hybrid Orbitals
Replies: 3
Views: 420

Re: Regions of Electron Density & Naming Hybrid Orbitals

When determining hybridization, we look at the Lewis structure and count lone pairs (and bonding pairs) as regions of electron density. And we do, whenever necessary, include lone pairs when we draw Lewis structures, meaning it is not considered atypical for a Lewis structure to have lone pairs.
Thu Oct 27, 2016 11:58 am
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge for Indivual Elements in Compound
Replies: 2
Views: 723

Re: Formal Charge for Indivual Elements in Compound

If there's an extra electron, it's a -1 charge. For example, if there are 6 electrons around N, there would be a -1 because N only has 5 valence electrons. If an electron is missing, it's a +1 charge. Going back to the N example, if N is surrounded by 4 electrons, it would have a +1 charge because a...
Fri Oct 21, 2016 11:18 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Placing elements in Lewis diagram
Replies: 1
Views: 273

Re: Placing elements in Lewis diagram

Normally you wouldn't place an element on top of the central element unless there's already elements on the left and right sides. So for example, for CO the O would be on the right side of C, and for CO2 the oxygens would be on the left and right sides, and for CO3 the oxygens would be on the left a...
Sun Oct 16, 2016 10:03 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: 3d and 4s orbitals
Replies: 2
Views: 842

Re: 3d and 4s orbitals

4s orbitals are lower in energy when there are no electrons in 3d orbitals, which is why 4s gets filled in first (according to the Aufbau principle). When 3d orbitals start filling up with electrons, they become lower in energy, and 4s orbitals become higher in energy. This is why 3d comes before 4s...
Thu Oct 06, 2016 4:12 pm
Forum: Photoelectric Effect
Topic: Module Questions
Replies: 1
Views: 334

Re: Module Questions

The energy required to release an electron is the threshold energy. When the energy of a photon is equal to the threshold energy, an electron will initially be released and will drift towards the electron detector due to the electrostatic attraction between the slightly positively charged detector a...
Thu Oct 06, 2016 3:29 pm
Forum: General Science Questions
Topic: Sig Figs
Replies: 1
Views: 638

Re: Sig Figs

If you look in the course reader, pages 35-36 tell us everything we need to know about sig figs. Also, I've noticed that sometimes our solution manual doesn't give us consistent sig fig values, but those are errors.
Fri Sep 30, 2016 2:40 pm
Forum: Photoelectric Effect