## Search found 26 matches

Sun Mar 19, 2017 7:02 pm
Forum: Second Order Reactions
Topic: Pre- equilibrium approach [ENDORSED]
Replies: 3
Views: 571

### Re: Pre- equilibrium approach[ENDORSED]

Usually when there's an intermediate involved, you have to use the pre equilibrium approach.
Sun Mar 12, 2017 10:43 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Winter 2016 final 4B
Replies: 4
Views: 631

### Re: Winter 2016 final 4B

O is a catalyst so it's not actually involved in the reaction
Fri Mar 03, 2017 5:08 pm
Forum: *Alkanes
Topic: Naming Organic Compounds (substituents)
Replies: 1
Views: 378

### 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
Mon Feb 27, 2017 1:24 am
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: k, temperature, and activation energy
Replies: 2
Views: 393

### 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
Mon Feb 20, 2017 9:30 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: Diamond and graphite
Replies: 8
Views: 1842

### 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.
Mon Feb 20, 2017 9:29 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: # of elementary steps?
Replies: 2
Views: 408

### Re: # of elementary steps?

They should give you the steps, otherwise any number of steps could technically occur.
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: 336

### 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...
Sat Feb 04, 2017 11:36 am
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Calculating Heat [ENDORSED]
Replies: 2
Views: 395

### Re: Calculating Heat[ENDORSED]

It sounds like it's referring to calculating the energy it takes to convert between states of matter.
Mon Jan 30, 2017 11:55 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Molecules and Disorder
Replies: 1
Views: 283

### 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
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: 553

### 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...
Tue Jan 24, 2017 12:50 pm
Forum: Calculating Work of Expansion
Topic: Combustion Reaction - Writing and Balancing
Replies: 2
Views: 401

### 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...
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: 286

### 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.
Sat Dec 03, 2016 7:41 pm
Forum: *Titrations & Titration Calculations
Topic: 2007 Final Q5
Replies: 2
Views: 693

### 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
Sat Dec 03, 2016 7:39 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Ice Table Variables
Replies: 1
Views: 334

### Re: Ice Table Variables

Actually, it's when x is less than 5% of the initial amount, after you calculate it. Not Ka.
Mon Nov 28, 2016 1:14 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Fall 2014 Final Exam #6A
Replies: 1
Views: 367

### 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.
Sun Nov 27, 2016 4:55 pm
Forum: Bronsted Acids & Bases
Topic: Strong and Weak Acids
Replies: 1
Views: 349

### 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.
Sun Nov 20, 2016 11:48 pm
Forum: Ideal Gases
Topic: Partial Pressure
Replies: 4
Views: 671

### 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.
Sun Nov 06, 2016 10:08 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Transition Metal Cations and H2O
Replies: 1
Views: 445

### 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...
Thu Oct 27, 2016 7:35 pm
Forum: Dipole Moments
Topic: Charge distribution in molecules
Replies: 1
Views: 334

### 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...
Fri Oct 21, 2016 4:56 pm
Forum: Electronegativity
Topic: Dipole moment
Replies: 2
Views: 470

### 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...
Fri Oct 21, 2016 4:47 pm
Forum: Lewis Structures
Topic: Lewis structure of H3PO4
Replies: 1
Views: 369

### 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)
Mon Oct 10, 2016 1:33 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 8040
Views: 1411436

### Re: Post All Chemistry Jokes Here

Gold walks into a bar. The bartender shouts "Ay you! Get out of here!"
Thu Oct 06, 2016 3:02 pm
Forum: Administrative Questions and Class Announcements
Topic: Midterm Date
Replies: 3
Views: 514

### Re: Midterm Date

Thank you!
Wed Oct 05, 2016 3:35 pm
Forum: Administrative Questions and Class Announcements
Topic: Midterm Date
Replies: 3
Views: 514

### Midterm Date

Is the midterm on Nov. 2nd at 4PM for those taking LS30A? just wanted to make sure. Thanks in advance!
Tue Sep 27, 2016 12:04 am
Forum: Properties of Light
Topic: Photons
Replies: 4
Views: 566

### 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).
Mon Sep 26, 2016 11:59 pm
Forum: Student Social/Study Group
Topic: Rieber Hall 14A Study Group (Fall 2016)
Replies: 49
Views: 7207

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

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