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
You should leave it and round off your final answer.
- 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
- Topic: Embarrassing question about BF3
- Replies: 1
- Views: 424
Re: Embarrassing question about BF3
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
- Topic: About photons.... [ENDORSED]
- Replies: 3
- Views: 502
Re: About photons.... [ENDORSED]
Dr. Lavelle mentioned that light is made of photon energy, meaning photons consist of energy. The amount of energy a photon has is determined by frequency. The higher the frequency, the higher the energy. Each photon need to have enough energy to interact with one metal atom to eject one electron. H...