Search found 25 matches

by Ann Zhang_1M
Fri Mar 17, 2017 11:25 pm
Forum: *Cycloalkanes
Topic: Carbon Number
Replies: 1
Views: 306

Carbon Number

When naming cycloalkanes with substituents, how do we number the carbon atoms?? After we start with the functional group occupying the #1 carbon or numbering the carbon atoms by following the alphabetical order, do we count the the rest of the atoms clock-wisely or anti-clockwisely? or do we need to...
by Ann Zhang_1M
Mon Mar 13, 2017 8:56 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7348
Views: 884830

Re: Post All Chemistry Jokes Here

A chemistry professor couldn't resist interjecting a little philosophy into a class lecture. He interrupted his discussion on balancing chemical equations, saying, "Remember, if you're not part of the solution, you're part of the precipitate!
by Ann Zhang_1M
Fri Mar 03, 2017 12:46 pm
Forum: *Electrophilic Addition
Topic: nucleophile and electrophile reactions
Replies: 6
Views: 878

nucleophile and electrophile reactions

When we are writing the formulas for nucleophile and electrophile reactions, do we need to use arrows to indicate the movement of electrons?
by Ann Zhang_1M
Mon Feb 27, 2017 8:47 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7348
Views: 884830

Re: Post All Chemistry Jokes Here

Why do chemists like nitrates so much?
They're cheaper than day rates
by Ann Zhang_1M
Mon Feb 27, 2017 8:45 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell potential
Replies: 4
Views: 531

Cell potential

when we calculate the standard cell potential of a redox reaction, how do we know if we should add two values or subtract. I am so confused.
by Ann Zhang_1M
Mon Feb 20, 2017 5:03 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7348
Views: 884830

Re: Post All Chemistry Jokes Here

The optimist sees the glass half full. The pessimist sees the glass half empty. The chemist sees the glass completely full, half with liquid and half with air.
by Ann Zhang_1M
Mon Feb 20, 2017 5:00 pm
Forum: Administrative Questions and Class Announcements
Topic: Quiz 2 Winter 2017
Replies: 160
Views: 14827

Re: Quiz 2 Winter 2017

how many questions are included in quiz2?
by Ann Zhang_1M
Sun Feb 05, 2017 11:42 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7348
Views: 884830

Re: Post All Chemistry Jokes Here

Don't trust atoms, they make up everything.
by Ann Zhang_1M
Sun Feb 05, 2017 11:39 pm
Forum: Phase Changes & Related Calculations
Topic: Random question
Replies: 3
Views: 481

Re: Random question

It depends on the substances that are involved in the reaction(number of bonds, bond enthalpies, etc.) or phase change.
by Ann Zhang_1M
Thu Jan 19, 2017 1:21 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: HW 8.73 (Bond Enthalpies
Replies: 5
Views: 681

Re: HW 8.73 (Bond Enthalpies

use the sum of bond enthalpies of all products minus the sum of bond enthalpies of all reactants.
and do not forget to multiply each bond with their moles
by Ann Zhang_1M
Fri Jan 13, 2017 12:41 am
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7348
Views: 884830

Re: Post All Chemistry Jokes Here

IF A KING FARTS, WILL IT BE A NOBLE GAS?
by Ann Zhang_1M
Fri Dec 02, 2016 1:11 am
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7348
Views: 884830

Re: Post All Chemistry Jokes Here

H2O is water and H2O2 is hydrogen peroxide. What is H2O4?
Drinking.
by Ann Zhang_1M
Wed Nov 23, 2016 10:09 am
Forum: Conjugate Acids & Bases
Topic: NH4+ and NH3
Replies: 3
Views: 3485

Re: NH4+ and NH3

In a neutralization reaction, an acid gives away one of its protons (ie H+ ion) to a base and forms its conjugate base, whereas the base accepts the proton and becomes its conjugate acid.
by Ann Zhang_1M
Wed Nov 23, 2016 10:07 am
Forum: Conjugate Acids & Bases
Topic: Determining Weak or Strong Bases/Acids
Replies: 4
Views: 655

Re: Determining Weak or Strong Bases/Acids

To determine whether an acid or a base is strong or weak, you need to know whether it ionizes completely.
Here's a list of strong acids and bases from http://www.austincc.edu/chemlab/strongacidbase
by Ann Zhang_1M
Thu Nov 17, 2016 1:40 pm
Forum: Amphoteric Compounds
Topic: How to tell something is amphoteric?
Replies: 4
Views: 1664

Re: How to tell something is amphoteric?

you can check if the compound can form H3O+ or OH- when it react with others.
If the compound can produce both when reacting with different reactants, it is amphoteric.
by Ann Zhang_1M
Thu Nov 17, 2016 1:37 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Kp
Replies: 6
Views: 764

Re: Kp

Kp actually means K, which can be regarded equivalently to Kc.
Pure substances like solids and liquid are not included in the calculation of equilibrium constant, no matter if it's Kp or Kc.
by Ann Zhang_1M
Tue Nov 15, 2016 12:46 am
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Tetrahedral complex and square-planar complex [ENDORSED]
Replies: 1
Views: 276

Tetrahedral complex and square-planar complex [ENDORSED]

how do you distinguish between tetrahedral complex and square-planar complex?
by Ann Zhang_1M
Sat Nov 12, 2016 1:03 am
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7348
Views: 884830

Re: Post All Chemistry Jokes Here

Did you know that oxygen went for a second date with potassium?
How did it go?
It went OK2!
by Ann Zhang_1M
Sat Nov 12, 2016 12:52 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Physical equilibrium and chemical equilibrium [ENDORSED]
Replies: 1
Views: 429

Physical equilibrium and chemical equilibrium [ENDORSED]

For Chem 14A, do we need to know about physical equilibrium?
Like the equilibrium between vapor and liquid in a closed container?
by Ann Zhang_1M
Sun Nov 06, 2016 11:11 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Shapes
Replies: 6
Views: 533

Re: Shapes

Yes, we do need to consider the lone pairs since the lone pairs repel other electrons and they can make the bond angle change. For example, if there are 2 molecules that both have 5 electron density regions, but 1 has only one lone pair in the central atom and another one has two, the molecular shap...
by Ann Zhang_1M
Sun Nov 06, 2016 11:06 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Expanded Valence Shell Electrons
Replies: 2
Views: 339

Expanded Valence Shell Electrons

For those elements that can accommodate more than 8 electrons, is it neseccary that P has 10 valence electrons, S has 12 electrons and Cl has 14 electrons?? Can P has more than 10, like 12??
by Ann Zhang_1M
Sat Oct 29, 2016 1:16 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7348
Views: 884830

Re: Post All Chemistry Jokes Here

Q: What is the name of 007's Eskimo cousin?
A: Polar Bond.
by Ann Zhang_1M
Sat Oct 29, 2016 1:13 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Do we need to know exact bond angles?
Replies: 3
Views: 417

Re: Do we need to know exact bond angles?

I don't think we need to know the exact values of bond angles. But we should be able to compare two bond angles when different molecular structures are given...
by Ann Zhang_1M
Sun Oct 23, 2016 2:45 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7348
Views: 884830

Re: Post All Chemistry Jokes Here

Q: What do you call a clown who's in jail?
A: A silicon.
by Ann Zhang_1M
Sun Oct 23, 2016 2:40 pm
Forum: Sigma & Pi Bonds
Topic: Quiz 2 Preparation [ENDORSED]
Replies: 8
Views: 2859

Re: Quiz 2 Preparation [ENDORSED]

I think we only need to review chapter 2 and 3 for Quiz 2 since the class announcement says the quiz will cover chapter2 and3. So we don't have to worry about the stuff of pi bond and sigma bond.

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