## Search found 20 matches

Mon Dec 04, 2017 5:06 pm
Forum: Administrative Questions and Class Announcements
Topic: Will there be a practice final? [ENDORSED]
Replies: 2
Views: 395

### Will there be a practice final?[ENDORSED]

For our midterm, there was a practice exam, so I am wondering if there will be one for the final as well?
Mon Dec 04, 2017 5:04 pm
Forum: Administrative Questions and Class Announcements
Topic: What is a passing grade? [ENDORSED]
Replies: 4
Views: 521

### Re: What is a passing grade?[ENDORSED]

From the syllabus, it states that the class does not use a curve, and that your grade is calculated out of the total 500 points. I may be misinterpreting it though!
Tue Nov 28, 2017 1:57 pm
Forum: Ideal Gases
Topic: Partial pressures
Replies: 4
Views: 488

### Re: Partial pressures

Solve for P using P= (n/v)(R)(T). They already give us the concentrations, which is mol.L, or n/v. Substitute the different concentrations into the equation and you get the respective pressures for each gas.
Tue Nov 28, 2017 1:44 pm
Forum: Ideal Gases
Topic: Test 4
Replies: 2
Views: 211

### Re: Test 4

At least be familiar with the ideal gas law. That formula proves very useful when calculating pressure or concentration.
Tue Nov 21, 2017 12:23 pm
Forum: Biological Examples
Topic: Cobalt
Replies: 4
Views: 345

### Re: Cobalt

Interesting sidenote: Cobalt (along with a few other elements) is also useful for producing and regulating enzymes!
Tue Nov 21, 2017 12:10 pm
Forum: Biological Examples
Topic: [Fe(NCS)(OH2)5]2+ name
Replies: 6
Views: 539

### Re: [Fe(NCS)(OH2)5]2+ name

Peter Dis1G wrote:Wait, do we need to know the names?

Knowing how to formulate the names of coordination compounds given its formula is important (and also I'm sure it's going to be on the quiz!)
Wed Nov 15, 2017 6:31 pm
Forum: Hybridization
Topic: Benzene Hybridization [ENDORSED]
Replies: 4
Views: 979

### Re: Benzene Hybridization[ENDORSED]

As you can see in this photo, there are 12 sigma bonds, not 18.

Tue Nov 14, 2017 6:20 pm
Forum: Hybridization
Topic: Purpose of hybridization [ENDORSED]
Replies: 5
Views: 2440

### Purpose of hybridization[ENDORSED]

What is the purpose of hybridization, and how is it different than using the VSEPR model?
Mon Nov 06, 2017 5:00 pm
Forum: Ionic & Covalent Bonds
Topic: Study Habits [ENDORSED]
Replies: 8
Views: 699

### Re: Study Habits[ENDORSED]

For me, I thoroughly read the chapter and review any concepts that I have trouble with. I then do several homework problems to ensure that I know the concept and knowledge. If there are online modules, I try to do those as well. Also, browsing chem community regularly throughout the week helps retai...
Mon Nov 06, 2017 4:11 pm
Forum: Resonance Structures
Topic: Determining Resonance Structures
Replies: 3
Views: 413

### Re: Determining Resonance Structures

I don't think there's a set way of finding the exact number of resonance structures... it's more like you keep doing them until you run out of combinations and find the most stable one.
Tue Oct 31, 2017 12:23 pm
Forum: Lewis Structures
Topic: 3.39 Format in Answer Sheet
Replies: 3
Views: 306

### Re: 3.39 Format in Answer Sheet

For 3.39 those Lewis structures are drawn based off of their ions because they are ionic compounds. You don't do this for all ions since compounds can also be covalent.
Tue Oct 31, 2017 11:51 am
Forum: Lewis Structures
Topic: Lewis Structures
Replies: 10
Views: 589

### Re: Lewis Structures

504909047 wrote:When asked for resonance, do you need every single possibility or just a few options?

I think that 2-3 possibilities is a good amount since the resonance examples we've done in class all had 2-3.
Tue Oct 24, 2017 1:01 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: 2.43 d) Tungsten [ENDORSED]
Replies: 1
Views: 180

### 2.43 d) Tungsten[ENDORSED]

Tungsten is in the same group as Cr, so why is the electron configuration [Xe] 4f^14 5d^4 6s^2 instead of [Xe] 4f^14 5d^5 6s^1 ?
Mon Oct 23, 2017 6:40 pm
Forum: Trends in The Periodic Table
Topic: d5 and d10 e- exception
Replies: 4
Views: 905

### Re: d5 and d10 e- exception

Yes, I believe so because in the HW, silver is in the same group as copper and its electron configuration is [Kr]4d^10 5s^1 instead of [Kr]4d^9 5s^2 due to certain elements being more stable with full orbitals rather than partially full orbitals. However, there are more exceptions/complications that...
Tue Oct 17, 2017 8:32 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Question about energy levels [ENDORSED]
Replies: 8
Views: 581

Is there a limit to the energy level an electron can reach? I know that n=1 is the lowest level for an atom, but does it cap around a specific higher energy level?
Mon Oct 16, 2017 11:52 pm
Forum: Einstein Equation
Topic: What is the eV unit? [ENDORSED]
Replies: 6
Views: 3184

### Re: What is the eV unit?[ENDORSED]

Courtney Cheney 3E wrote:Is it necessary to memorize the conversion $1eV=1.602 \times 10^{-19}$J?

Yes, I recommend that you memorize it since some problems in the book are in keV and eV. But that conversion you listed is given on the test anyway.
Thu Oct 12, 2017 10:05 pm
Forum: Einstein Equation
Topic: question 27
Replies: 2
Views: 307

### Re: question 27

Alternatively, you could also divide to cancel out units:

64 J / [(4.7 x 10^-19) J.photon^-1] = 1.4 x 10^20 photons.

Notice how the joules cancel out!
Tue Oct 10, 2017 11:20 pm
Forum: Properties of Light
Topic: HW 1.37
Replies: 1
Views: 175

### HW 1.37

Protons and neutrons have nearly the same mass. How different are their wavelengths? Calculate the wavelength of each particle when traveling at 2.75 x 10^5 m/s in a particle accelerator and report the difference as a percentage of the wavelength of the neutron.

Can someone help?
Tue Oct 03, 2017 6:15 pm
Forum: Balancing Chemical Reactions
Topic: Problem F.13
Replies: 2
Views: 293

### Re: Problem F.13

First you have to find the moles of P and Cl: Phosphorus: 4.14g/30.97g.mol = 0.134 mol P For chlorine, since the total amount of product is 27.8 g, you have to subtract 4.14 from 27.8 to find the amount of chlorine in the reactants: 27.8 - 4.14g / 35.45g.mol = 0.667 mol Cl Next, just find the empiri...
Tue Oct 03, 2017 5:37 pm
Forum: Balancing Chemical Reactions
Topic: Help on HW question H1
Replies: 5
Views: 334

### Help on HW question H1

Hey all, so the question says: It appears that balancing the chemical equation Cu + SO2 --> CuO + S would be simple if we could just add another O atom to the product side: Cu + SO2 --> CuO + S + O. a) Why is that balancing procedure not allowed? b) Balance the equation correctly. So I know how to a...