Search found 20 matches

by Shani Chung 2C
Sat Mar 12, 2016 9:36 am
Forum: Interesting Applications: Rechargeable Batteries (Cell Phones, Notebooks, Cars), Fuel Cells (Space Shuttle), Photovoltaic Cells (Solar Panels), Electrolysis, Rust
Topic: Electrolysis
Replies: 2
Views: 788

Re: Electrolysis

Electrolysis is when an electrical current is used to drive a nonspontaneous redox reaction (E cell is negative). Oxidation still occurs at the anode, reduction at the cathode and the electrons flow from the anode to the cathode. The main difference is that the anode is positively charged and the ca...
by Shani Chung 2C
Mon Mar 07, 2016 9:04 am
Forum: Administrative Questions and Class Announcements
Topic: Video Competition
Replies: 66
Views: 25304

Re: Video Competition

Here's my video uploaded to here! Sorry about that!
Shani Chung- Lecture 2
by Shani Chung 2C
Fri Mar 04, 2016 8:36 pm
Forum: Administrative Questions and Class Announcements
Topic: Video Competition
Replies: 66
Views: 25304

Re: Video Competition

Here's my video explaining the quadratic formula!

Shani Chung- Lecture 2

https://www.youtube.com/watch?v=OL5zzFGxPoE&feature=youtu.be
by Shani Chung 2C
Fri Feb 26, 2016 11:07 am
Forum: *Electrophiles
Topic: Structure of Ethyloxonium
Replies: 1
Views: 326

Structure of Ethyloxonium

The structure of ethyloxonium is on page 156 in the organic chemistry textbook. Can someone explain to me why the oxygen of that molecule is positive?
by Shani Chung 2C
Sat Feb 20, 2016 11:51 am
Forum: *Electrophiles
Topic: Friedal-Crafts alkylation
Replies: 3
Views: 555

Re: Friedal-Crafts alkylation

I think it's because there is a difference in electronegativity between the Cl and C so the Cl can pull on the electrons of the C-Cl bond. There isn't much difference in electronegativity between C and H
by Shani Chung 2C
Mon Feb 08, 2016 5:03 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Inert Electrodes- 14.13 Part B and 14.23 Part A
Replies: 1
Views: 367

Inert Electrodes- 14.13 Part B and 14.23 Part A

I understand that inert electrodes are used when the solid form of an aqueous solution is not available. However, in problem 14.13 Part B, there is the solid version of I - which is I 2 (s), but in the answers platinum was used as an inert electrode. Also in problem 14.23 part A, the Hg(l) and Hg 2 ...
by Shani Chung 2C
Fri Feb 05, 2016 11:58 pm
Forum: Balancing Redox Reactions
Topic: OIL RIG
Replies: 1
Views: 540

Re: OIL RIG

That's really helpful! Thanks! I also learned Red Cat, which reminds you that reduction takes place at the cathode!
by Shani Chung 2C
Fri Jan 29, 2016 4:33 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Redox in Gold Ring example
Replies: 1
Views: 424

Re: Redox in Gold Ring example

The reason why the oxidation equation has an negative value is because the equation has already been flipped. If you are using the equation reduction- oxidation, you use the values you get from the standard reduction potentials and you don't manipulate any of the equations. The reason why the gold r...
by Shani Chung 2C
Fri Jan 22, 2016 10:38 am
Forum: Calculating Work of Expansion
Topic: Types of Systems
Replies: 3
Views: 672

Re: Types of Systems

I think for both irreversible and reversible systems are closed systems since they both just deal with the transfer of energy
by Shani Chung 2C
Fri Jan 15, 2016 11:34 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Reversible and Irreversible Process
Replies: 2
Views: 403

Re: Reversible and Irreversible Process

Yeah it really depends on the conditions that the problem gives you. If the system is at equilibrium then it will be reversible. Otherwise it will be irreversible.
by Shani Chung 2C
Fri Jan 08, 2016 11:37 am
Forum: Phase Changes & Related Calculations
Topic: Standard Enthalpy
Replies: 2
Views: 458

Re: Standard Enthalpy

All substances must be in their standard states at 1 atm. If the standard state of the substance is a solution then it must have a concentration of 1 M. And if it's a pure substance or solvent then it must be a pure liquid or solid
by Shani Chung 2C
Mon Nov 30, 2015 10:22 pm
Forum: *Making Buffers & Calculating Buffer pH (Henderson-Hasselbalch Equation)
Topic: Use of Salt in Buffer Solution
Replies: 1
Views: 450

Use of Salt in Buffer Solution

If you're trying to create a buffer solution with a weak acid, for instance CH3COOH, you add a salt containing it's conjugate base, CH3COO-, in order to make [CH3COOH]= [CH3COO-]. However, doesn't CH3COO- prefer it's molecular form? So won't it react with water to form CH3COOH?
by Shani Chung 2C
Fri Nov 27, 2015 10:10 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Identity of strong and weak bases and acids
Replies: 1
Views: 784

Re: Identity of strong and weak bases and acids

I would just memorize all of the strong acids and bases and know that anything else would be weak. A list of them are in the course reader. The strong acids are HCl, HBr, HI (Hydrogen + the halogens- not including F), HNO3, H2SO4 and HClO4. The strong bases are the alkali metal hydroxides- LiOH, NaO...
by Shani Chung 2C
Fri Nov 20, 2015 5:14 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Units for Partial Pressure When Given Kp
Replies: 2
Views: 633

Units for Partial Pressure When Given Kp

When you're given Kp and the concentration of reactants and you're trying to figure the out the partial pressure of the products and reactants when at equilibrium, what units do you use? Bars or atm?
by Shani Chung 2C
Fri Nov 13, 2015 5:15 pm
Forum: Ideal Gases
Topic: Maxwell-Boltzmann Distribution
Replies: 1
Views: 481

Re: Maxwell-Boltzmann Distribution

Right, there are more molecules at a faster speed when the temperature is increased. I think these equations are just saying that as the temperature increases, the average kinetic energy of the gas increases.
by Shani Chung 2C
Wed Nov 04, 2015 8:25 am
Forum: Resonance Structures
Topic: Preferred Resonance Structure of SO2 and (PO4)3-
Replies: 1
Views: 1024

Preferred Resonance Structure of SO2 and (PO4)3-

For problem 5B in the 2012 midterm, SO2 is drawn with one double bonded oxygen and one single bonded oxygen. Wouldn't it make more sense for both of the oxygens to have double bonds so that their formal charges would be zero and the formal charge of S would also be zero? The same goes with (PO4)3-(P...
by Shani Chung 2C
Fri Oct 30, 2015 6:31 pm
Forum: Dipole Moments
Topic: Polarity of O3
Replies: 1
Views: 1243

Polarity of O3

The book says that O3 is polar. Can anyone explain to me why that is? I thought that in order to have a polar molecule, you would need bonds with a difference in electronegativity, but since it's a molecule consisting of only oxygen, there would be no difference. Thanks!
by Shani Chung 2C
Fri Oct 23, 2015 9:45 pm
Forum: Hybridization
Topic: Unhybridized p orbitals
Replies: 1
Views: 620

Re: Unhybridized p orbitals

I think that if there are less than four regions of electron density, then there'd be hybridized p orbitals. For example, in 2sp^2 only two p orbitals are used and there would be one unhybridized p orbital.
by Shani Chung 2C
Fri Oct 16, 2015 4:43 pm
Forum: Ionic & Covalent Bonds
Topic: More than Octect
Replies: 5
Views: 988

Re: More than Octect

I think it has something to do with the energy levels and how in an expanded octet, the two additional electrons cannot be from the 4th energy level. That would also explain why electrons in the n=2 energy level cannot have an expanded octet because electrons cannot be put in the 3s orbital and ther...
by Shani Chung 2C
Wed Oct 07, 2015 9:22 pm
Forum: Significant Figures
Topic: Sig Figs in Percentages
Replies: 1
Views: 12360

Sig Figs in Percentages

When your final answer is a percentage how many sig figs do you report? Do you use as many sig figs as the numbers that are given to you? Or do you report two places after the decimal like 54.56%? I've seen different textbooks do it different ways.

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