Search found 26 matches

by Theresa Dinh 3F
Sun Mar 19, 2017 7:02 pm
Forum: Second Order Reactions
Topic: Pre- equilibrium approach [ENDORSED]
Replies: 3
Views: 444

Re: Pre- equilibrium approach [ENDORSED]

Usually when there's an intermediate involved, you have to use the pre equilibrium approach.
by Theresa Dinh 3F
Sun Mar 12, 2017 10:43 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Winter 2016 final 4B
Replies: 4
Views: 535

Re: Winter 2016 final 4B

O is a catalyst so it's not actually involved in the reaction
by Theresa Dinh 3F
Fri Mar 03, 2017 5:08 pm
Forum: *Alkanes
Topic: Naming Organic Compounds (substituents)
Replies: 1
Views: 319

Re: Naming Organic Compounds (substituents)

usually when naming organic compounds, you want to put the substituent as close to 1 as possible when naming. that's probably why
by Theresa Dinh 3F
Mon Feb 27, 2017 1:24 am
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: k, temperature, and activation energy
Replies: 2
Views: 305

Re: k, temperature, and activation energy

At higher temperatures, molecules are moving a lot faster because there is more energy in the environment (temperature is the measure of heat, which is energy in the environment). Because of this, they are more likely to be able to collide at the required energy level
by Theresa Dinh 3F
Mon Feb 20, 2017 9:30 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: Diamond and graphite
Replies: 8
Views: 632

Re: Diamond and graphite

Calculating by kinetics (by k and stuff) provides an answer that is mostly stable for diamond, but the thermodynamic equations (gibbs free energy) show that it is unstable.
by Theresa Dinh 3F
Mon Feb 20, 2017 9:29 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: # of elementary steps?
Replies: 2
Views: 332

Re: # of elementary steps?

They should give you the steps, otherwise any number of steps could technically occur.
by Theresa Dinh 3F
Fri Feb 10, 2017 4:45 pm
Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
Topic: Question 3 from Quiz 1
Replies: 1
Views: 275

Re: Question 3 from Quiz 1

They are not perfect crystals, which is the problem. Thus they cannot be exactly S=0. You have to figure out the entropy using the equation S = K ln W W is the number of different configurations that a molecule can have. Since SF6 has only one configuration, but SF5CL can have many different configu...
by Theresa Dinh 3F
Sat Feb 04, 2017 11:36 am
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Calculating Heat [ENDORSED]
Replies: 2
Views: 316

Re: Calculating Heat [ENDORSED]

It sounds like it's referring to calculating the energy it takes to convert between states of matter.
by Theresa Dinh 3F
Mon Jan 30, 2017 11:55 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Molecules and Disorder
Replies: 1
Views: 227

Re: Molecules and Disorder

Polarity should not have anything to do with disorder, because it is less to do with energy and more to do with attraction
by Theresa Dinh 3F
Tue Jan 24, 2017 12:57 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Ch 8 Exercise 77
Replies: 3
Views: 414

Re: Ch 8 Exercise 77

According to an online source ( http://web.chem.ucla.edu/~harding/IGOC/K/kekule_structure.html ) it is a Lewis structure in which bonded electron pairs in covalent bonds are shown as lines and avoids showing lone pairs. Resonance just makes the kekule structure show two different versions of benzene...
by Theresa Dinh 3F
Tue Jan 24, 2017 12:50 pm
Forum: Calculating Work of Expansion
Topic: Combustion Reaction - Writing and Balancing
Replies: 2
Views: 329

Re: Combustion Reaction - Writing and Balancing

H2O is normally a liquid. Especially since the combustion reaction appears to be just two liquids reacting with each other, which means that most likely they are not heating up enough to react. O2 liquid is usually found in only extremely cold temperatures. You can double the equation if needed, but...
by Theresa Dinh 3F
Thu Jan 12, 2017 2:10 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: standard reaction enthalpy
Replies: 2
Views: 218

Re: standard reaction enthalpy

I am pretty sure we will be given standard reaction enthalpies if it is needed. Otherwise, it'll be something we need to figure out from the problem provided, so it wouldn't be provided at that point.
by Theresa Dinh 3F
Sat Dec 03, 2016 7:41 pm
Forum: *Titrations & Titration Calculations
Topic: 2007 Final Q5
Replies: 2
Views: 580

Re: 2007 Final Q5

Don't we get a list of weak and strong acids? Also, you can derive the formula from the name. Methyl = CH3, Amine = NH2
by Theresa Dinh 3F
Sat Dec 03, 2016 7:39 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Ice Table Variables
Replies: 1
Views: 279

Re: Ice Table Variables

Actually, it's when x is less than 5% of the initial amount, after you calculate it. Not Ka.
by Theresa Dinh 3F
Mon Nov 28, 2016 1:14 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Fall 2014 Final Exam #6A
Replies: 1
Views: 282

Re: Fall 2014 Final Exam #6A

They basically just simplified the problem and substituted in the Kc value. The Equation is merely a simplified way of writing out the complicated fractions.
by Theresa Dinh 3F
Sun Nov 27, 2016 4:55 pm
Forum: Bronsted Acids & Bases
Topic: Strong and Weak Acids
Replies: 1
Views: 289

Re: Strong and Weak Acids

No, it is not considered to be in equilibrium. The rate of change for the forward reaction must equal the rate of change for the opposite reaction in order to be considered at equilibrium.
by Theresa Dinh 3F
Sun Nov 20, 2016 11:48 pm
Forum: Ideal Gases
Topic: Partial Pressure
Replies: 4
Views: 589

Re: Partial Pressure

I believe sometimes when a reaction occurs, the changes in the amount of reactants and products can sometimes balance out to make an overall no change in pressure.
by Theresa Dinh 3F
Sun Nov 06, 2016 10:08 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Transition Metal Cations and H2O
Replies: 1
Views: 363

Re: Transition Metal Cations and H2O

I read somewhere that it's because despite H2O having two pairs, the H2O prefers not to share the second pair of electrons, so technically that would make the H2O provide the same amount of electrons as the other elements. Don't quote me exactly on this however. I have also read that a ligand's stre...
by Theresa Dinh 3F
Thu Oct 27, 2016 7:35 pm
Forum: Dipole Moments
Topic: Charge distribution in molecules
Replies: 1
Views: 267

Re: Charge distribution in molecules

Which parts specifically do you need explaining in this section? In short, this section basically talks about how each element has its own level of strength when pulling in electrons. Just like how each person can lift a certain weight, each element has its own pull on electrons. Because of this, el...
by Theresa Dinh 3F
Fri Oct 21, 2016 4:56 pm
Forum: Electronegativity
Topic: Dipole moment
Replies: 2
Views: 380

Re: Dipole moment

There are different degrees of polarity, and this arises mostly due to the electronegativity of elements (how strong they pull on the electrons). Oxygen is known for having high electronegativity, which means it pulls it very strongly while H is known for being weaker, which is also why water is a p...
by Theresa Dinh 3F
Fri Oct 21, 2016 4:47 pm
Forum: Lewis Structures
Topic: Lewis structure of H3PO4
Replies: 1
Views: 253

Re: Lewis structure of H3PO4

It's probably more accurate to draw it the second way, just because that's how the molecule works normally, and the first method is more for two molecular ions rather than a single element and a molecule (eg (nh3)3PO4)
by Theresa Dinh 3F
Mon Oct 10, 2016 1:33 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7582
Views: 1015282

Re: Post All Chemistry Jokes Here

Gold walks into a bar. The bartender shouts "Ay you! Get out of here!"
by Theresa Dinh 3F
Thu Oct 06, 2016 3:02 pm
Forum: Administrative Questions and Class Announcements
Topic: Midterm Date
Replies: 3
Views: 384

Re: Midterm Date

Thank you!
by Theresa Dinh 3F
Wed Oct 05, 2016 3:35 pm
Forum: Administrative Questions and Class Announcements
Topic: Midterm Date
Replies: 3
Views: 384

Midterm Date

Is the midterm on Nov. 2nd at 4PM for those taking LS30A? just wanted to make sure. Thanks in advance!
by Theresa Dinh 3F
Tue Sep 27, 2016 12:04 am
Forum: Properties of Light
Topic: Photons
Replies: 4
Views: 448

Re: Photons

I believe that it is because the higher the frequency the stronger it is. For example a radio wave, which has a low frequency rate, is weaker than a gamma ray, which has a high frequency (due to shorter wavelength).
by Theresa Dinh 3F
Mon Sep 26, 2016 11:59 pm
Forum: Student Social/Study Group
Topic: Rieber Hall 14A Study Group (Fall 2016)
Replies: 49
Views: 4405

Re: Rieber Hall 14A Study Group (Fall 2016)

I'm from Rieber Vista, and this sounds pretty cool. Where would the meeting place be?

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