Search found 58 matches
- Sun Mar 17, 2019 9:16 am
- Forum: Zero Order Reactions
- Topic: Zero order reaction
- Replies: 8
- Views: 970
Re: Zero order reaction
It is zero order if its concentration has no effect on the rate.
- Sun Mar 17, 2019 9:13 am
- Forum: General Rate Laws
- Topic: Slow elementary step
- Replies: 2
- Views: 518
Re: Slow elementary step
The rate cannot be any faster than its slowest step, therefore, it determines the rate.
- Sun Mar 17, 2019 9:11 am
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Arrhenius eq
- Replies: 3
- Views: 661
Re: Arrhenius eq
In class, Dr. Lavelle had said to assume A=1 unless otherwise stated.
- Sun Mar 17, 2019 9:10 am
- Forum: General Rate Laws
- Topic: mmol units
- Replies: 2
- Views: 582
Re: mmol units
I think you'd only need to convert so you can have the same units across. One of the problems has mmol and mol so units for mmol were converted to mol. But the other problem had only mmol units, so no conversion was necessary. The units of the initial rate and initial concentrations should match up.
- Sat Mar 16, 2019 12:08 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Test Location 14B W19
- Replies: 3
- Views: 646
Re: Test Location 14B W19
Here you go...
- Sat Mar 16, 2019 11:59 am
- Forum: Administrative Questions and Class Announcements
- Topic: LYNDON'S PORK RAMEN REVIEW
- Replies: 37
- Views: 7384
Re: LYNDON'S PORK RAMEN REVIEW
Thank You Lyndon!
- Fri Mar 15, 2019 8:33 pm
- Forum: Student Social/Study Group
- Topic: Studying for the Final
- Replies: 25
- Views: 2706
Re: Studying for the Final
That along with the making sure to know everything mentioned in the outlines.
- Sat Mar 09, 2019 11:09 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Microscopic reversibility
- Replies: 4
- Views: 455
Re: Microscopic reversibility
Microscopic reversibility assumes that the reaction has the same pathway for forward and reverse directions.
- Sat Mar 09, 2019 10:21 pm
- Forum: Second Order Reactions
- Topic: Final
- Replies: 32
- Views: 2283
Re: Final
As everyone said, it is cumulative, and the best preparation is to look at the outlines for each optic covered and make sure you understand all of the bullet points listed. Dr. Labels suggests practicing textbook homework problems is the best preparation.
- Sat Mar 09, 2019 10:16 pm
- Forum: Second Order Reactions
- Topic: rate constant k
- Replies: 3
- Views: 404
Re: rate constant k
You can think about it as a rate not proceeding negatively. It can be slow, or you can have a reverse rate, but a “negative” rate is not possible.
- Wed Feb 27, 2019 6:24 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Galvanic Cell Inert Component
- Replies: 1
- Views: 229
Re: Galvanic Cell Inert Component
An inert electrode is used when there is a gas/ion electrode reaction or when both oxidized and reduced species are in the same solution, meaning there's no conducting solid.
- Mon Feb 25, 2019 5:37 pm
- Forum: General Science Questions
- Topic: Test #2
- Replies: 2
- Views: 609
Re: Test #2
This is from the website :)
- Sun Feb 24, 2019 12:00 am
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3004661
- Sat Feb 23, 2019 11:51 pm
- Forum: Calculating Work of Expansion
- Topic: Equations for work
- Replies: 7
- Views: 863
Re: Equations for work
Adding to that, for the third equation, when pressure is changing, you'd use w=-nRT ln (p1/p2).
- Sat Feb 23, 2019 11:44 pm
- Forum: Van't Hoff Equation
- Topic: Galvanic/Voltaic Cell
- Replies: 2
- Views: 281
Re: Galvanic/Voltaic Cell
From what I've read, they're used interchangeably.
- Fri Feb 15, 2019 1:46 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Gibbs free energy
- Replies: 5
- Views: 480
Re: Gibbs free energy
If the value is negative, then it's spontaneous and favors product formation and if the value is positive, then it's non spontaneous and does not favor formation of products.
- Fri Feb 15, 2019 1:43 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: work and Gibbs Free Energy
- Replies: 2
- Views: 276
Re: work and Gibbs Free Energy
If Gibbs free energy is negative, that means the process is spontaneous and releases energy. Free energy is described as the energy that is available to do work.
- Fri Feb 15, 2019 1:37 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Microstate
- Replies: 7
- Views: 785
Re: Microstate
When there are more microstates, there is increased entropy. This is because there is greater positional/residual vibration between molecules and that lends to greater disorder.
- Fri Feb 08, 2019 2:32 am
- Forum: Administrative Questions and Class Announcements
- Topic: Midterm Review Sessions
- Replies: 1
- Views: 353
Re: Midterm Review Sessions
The TA or LA will usually post a practice worksheet on here for us to do before the review session, so that way they can just go through the solutions and answer any questions. But sometimes no worksheets are given and it's more note dependent based on the review session you attend.
- Fri Feb 01, 2019 10:09 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Different Kinds of Symptoms
- Replies: 6
- Views: 1222
Re: Different Kinds of Symptoms
Insulation only helps identify isolated systems. If there is no insulation you'd still have to determine whether the system was open or closed.
- Fri Feb 01, 2019 10:01 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Enthalpies
- Replies: 5
- Views: 483
Re: Enthalpies
Yes, an increase of enthalpy means that the system was supplied with energy/heat. ^
- Fri Feb 01, 2019 9:58 pm
- Forum: Phase Changes & Related Calculations
- Topic: Chemical potential energy
- Replies: 4
- Views: 319
Re: Chemical potential energy
Yes, you should get the same answer if you do the long method. ^
- Sat Jan 26, 2019 11:54 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Enthalpy Units
- Replies: 7
- Views: 718
Re: Enthalpy Units
The standard enthalpy of formation is the enthalpy change when 1 mole of a substance is formed from its element(s). Note that all the substances should be in standard state.
- Wed Jan 23, 2019 11:30 am
- Forum: Ideal Gases
- Topic: atm vs. bar?
- Replies: 25
- Views: 2820
Re: atm vs. bar?
Regarding pressure, they're both just units measurements. But if you wanted to figure out concentration you would need to use atm. For example, if you're given partial pressure but the units are in bar and you want to use PV=nRT to find concentration (with volume given), you'd need to convert to atm...
- Tue Jan 22, 2019 4:19 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Homework for Week 3
- Replies: 5
- Views: 471
- Sun Jan 20, 2019 11:04 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: The Conjugate Seesaw
- Replies: 13
- Views: 935
Re: The Conjugate Seesaw
MadelineHlobik wrote:Does Kw=Ka*Kb and Kw=[H3O][OH]
Yes, so since Kw = 10^-14, [H30+] has to be 10^-7 and [OH-] has to be 10^-7 as well.
- Sun Jan 20, 2019 10:59 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Pressure Notation
- Replies: 5
- Views: 454
Re: Pressure Notation
Kp should not have any units because it is an activity. ^
- Sun Jan 20, 2019 10:56 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Q VS. K
- Replies: 13
- Views: 1594
Re: Q VS. K
K is basically the Q, but at equilibrium.
- Fri Jan 11, 2019 11:18 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Concentration of P using the Quadratic Formula
- Replies: 3
- Views: 151
Re: Concentration of P using the Quadratic Formula
Also keep in mind to discard the negative answer (of the two) you get because the concentration must always be a positive value.
- Fri Jan 11, 2019 11:12 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Changing Pressure
- Replies: 6
- Views: 526
Re: Changing Pressure
Adding an inert gas wouldn't affect the equilibrium because the concentrations of the reactant and product would remain the same, meaning there would be no change in the equation.
- Fri Jan 11, 2019 11:07 pm
- Forum: Ideal Gases
- Topic: Notation [ENDORSED]
- Replies: 5
- Views: 542
Re: Notation [ENDORSED]
Yes, my TA usually uses parenthesis or nothing at all when doing a problem with partial pressure. With concentration, brackets are always used.
- Sun Dec 09, 2018 6:43 am
- Forum: Biological Examples
- Topic: Cisplatin
- Replies: 7
- Views: 1266
Re: Cisplatin
904837647 wrote:Will cisplatin be apart of what we need to know on the final?
The syllabus says "Discuss well-known examples of coordination compounds used as chemotherapy drugs." so it would be a good idea to know it.
- Sun Dec 09, 2018 6:40 am
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Ligand order
- Replies: 1
- Views: 231
Re: Ligand order
They are namedin alphabetical order (ignoring Greek prefixes). Ex: for pentaammine, you would look at the A in ammine rather than the P in penta.
- Sun Dec 09, 2018 6:31 am
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: Polarizability vs. Polarizing Power
- Replies: 2
- Views: 492
Re: Polarizability vs. Polarizing Power
Polarizability is how easy it is to pull the electron cloud of a molecule, whereas polarizing power is how good an atom is at pulling on bonding electrons. They are inversely related.
- Sun Dec 09, 2018 6:24 am
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: polarizability
- Replies: 1
- Views: 383
Re: polarizability
That's correct.
- Sun Dec 09, 2018 6:22 am
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: polarizing power
- Replies: 3
- Views: 688
Re: polarizing power
Polarizability is how easy it is to pull the electron cloud of a molecule, whereas polarizing power is how good an atom is at pulling on bonding electrons. They are inversely related.
- Sun Dec 09, 2018 6:19 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Polarity
- Replies: 2
- Views: 319
Re: Polarity
No, if there's multiple lone pairs, their magnitude/direction can cancel out leaving you with a non polar molecule.
- Sun Dec 09, 2018 6:17 am
- Forum: Naming
- Topic: ethylenediamine [ENDORSED]
- Replies: 4
- Views: 665
Re: ethylenediamine [ENDORSED]
That's right, because it already has "di" in its name.
- Sat Dec 08, 2018 4:12 pm
- Forum: Administrative Questions and Class Announcements
- Topic: FINAL PRACTICE - Lyndon's Churro Review Session [ENDORSED]
- Replies: 118
- Views: 20821
Re: FINAL PRACTICE - Lyndon's Churro Review Session [ENDORSED]
These practice problems and review sessions are so helpful. Thank you Lyndon!
- Sat Dec 08, 2018 4:10 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: Calculating pH and the pOH
- Replies: 2
- Views: 317
Re: Calculating pH and the pOH
You would first find the pH by calculating pH=-log[H3O+] and then subtract your answer from 14 to get the POH.
- Sat Dec 08, 2018 4:07 pm
- Forum: Naming
- Topic: adding "ion" at the end of a name
- Replies: 4
- Views: 412
Re: adding "ion" at the end of a name
Lyndon had mentioned in his review session that it's good practice to do so, just to be safe. However I don't think you'd be docked points if you didn't add it.
- Sat Dec 08, 2018 4:05 pm
- Forum: General Science Questions
- Topic: FINAL
- Replies: 3
- Views: 565
Re: FINAL
Dr. Lavelle had sent out this link in an email explaining that this is a topic we'll cover in 14B.
viewtopic.php?f=60&t=38752
viewtopic.php?f=60&t=38752
- Sat Dec 08, 2018 4:02 pm
- Forum: Student Social/Study Group
- Topic: Structure of the final
- Replies: 4
- Views: 830
Re: Structure of the final
Lavelle had said in class that it would be similar to the structure of the midterm, so I'm guessing about 8 questions with multiple parts to them and maybe a couple multiple choice questions.
- Tue Nov 27, 2018 10:05 am
- Forum: Hybridization
- Topic: Number
- Replies: 2
- Views: 206
Re: Number
Hybridization is based on regions of electron density. Therefore lone pairs would be included.
- Sun Nov 25, 2018 11:56 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Sigma and Pi Bonds
- Replies: 3
- Views: 311
Re: Sigma and Pi Bonds
Sigma bonds allow for free rotation of atoms. With pi bonds the whole molecule has to rotate, and single atoms cannot rotate freely.
- Sun Nov 25, 2018 11:49 pm
- Forum: Electronegativity
- Topic: Electronegativity Values
- Replies: 4
- Views: 715
Re: Electronegativity Values
The electronegativity values will be given to us in a problem. Otherwise, just follow the electronegativity trend for the periodic table to gauge if the values are lesser or greater than a value given.
- Sun Nov 25, 2018 11:45 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: VSEPR
- Replies: 9
- Views: 669
Re: VSEPR
The stronger the bond, the greater the repulsion strength. For example, a triple bond has greater repulsion strength than a double than a single bond.
- Sun Nov 18, 2018 11:23 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Dipole moments
- Replies: 8
- Views: 3298
Re: Dipole moments
It's also helpful to consider dipole moments similar to vectors. We would take into account magnitude and direction when cancelling out/ adding up vectors, and the same idea applies to dipole moments.
- Sun Nov 18, 2018 11:17 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: lone pair influence on shape
- Replies: 12
- Views: 4211
Re: lone pair influence on shape
Can someone explain the difference between bent and linear? A linear shape is when the bond angles are 180 degrees exactly. This could even take place in the presence of 2 or more lone pairs depending on the amount of regions of electron density. A bent shape, however occurs when the linear shape i...
- Sun Nov 18, 2018 11:06 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: lone pair influence on shape
- Replies: 12
- Views: 4211
Re: lone pair influence on shape
Also in discussion, my TA had said that paired electrons are more repulsed by lone pairs of electrons than they are by other bonded pairs of electrons. Which can also explain why they'd more readily move closer to another bonded pair in the presence of lone electrons.
- Sun Nov 18, 2018 11:01 pm
- Forum: *Liquid Structure (Viscosity, Surface Tension, Liquid Crystals, Ionic Liquids)
- Topic: Shape and Boiling Point
- Replies: 12
- Views: 3015
Re: Shape and Boiling Point
Does the distance between the bonds effect the boiling point? Would this cause the bond to be stronger or weaker? The longer the bond the weaker it is. For instance double bonds are shorter and stronger than single bonds and triple bonds are shorter and stronger than double and single bonds. Yes, a...
- Mon Nov 05, 2018 3:23 pm
- Forum: Administrative Questions and Class Announcements
- Topic: MIDTERM PRACTICE - Garlic Bread Review Session [ENDORSED]
- Replies: 121
- Views: 17184
Re: MIDTERM PRACTICE - Garlic Bread Review Session [ENDORSED]
Hilda Sauceda 3C wrote:Can anyone explain the reasoning for why 6d is true.
6d is true because the answer 10^-11 m is greater 10^-18. If it were less, then wavelength properties wouldn't be measurable.
- Tue Oct 09, 2018 12:26 am
- Forum: Significant Figures
- Topic: All students read this sig fig post [ENDORSED]
- Replies: 170
- Views: 33557
Re: All students read this sig fig post [ENDORSED]
Can someone help me with a quick review of zeros in sig figs? I always get confused as to which zeros count as significant and which ones do not. 1. All non zero numbers are significant. ex) 613 has 3 sig figs 2. Zeros located between non-zero digits are significant ex) 5004 has 4 sig figs 3. Trail...
- Tue Oct 09, 2018 12:11 am
- Forum: SI Units, Unit Conversions
- Topic: How does grading for discussion posts work?
- Replies: 80
- Views: 8163
Re: How does grading for discussion posts work?
I think that "in order for you to receive the 3 points for the discussion, you need to either post a question, answer a question or put a comment relevant to the question on a post, 3 times a week." that's what one of the TA's told me. Are the posts due by the time we have our discussion ...
- Tue Oct 09, 2018 12:08 am
- Forum: SI Units, Unit Conversions
- Topic: How does grading for discussion posts work?
- Replies: 80
- Views: 8163
Re: How does grading for discussion posts work?
Danny Elias Dis 1E wrote:If we were to post four times in one week, would the extra post roll over to next week's grading?
I don't think it would since the idea is to have 3 engagements weekly rather than finish them all in one week.
- Wed Oct 03, 2018 5:46 pm
- Forum: Limiting Reactant Calculations
- Topic: Percent yield
- Replies: 10
- Views: 940
Re: Percent yield
Actual yield should be given and if it is not then you cannot determine percent yield . The theoretical yield (what you'd calculate) is what would be produced in a perfect reaction with nothing lost (due to heat/ measuring errors/ etc.). The actual yield is usually an experimental value and therefor...
- Tue Oct 02, 2018 8:10 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Advice from a Medical Student [ENDORSED]
- Replies: 297
- Views: 382845
Re: Advice from a Medical Student [ENDORSED]
Thank you so much for this! I'm going into medicine too and hearing your insight made me feel so much better. :)
- Tue Oct 02, 2018 8:03 pm
- Forum: Limiting Reactant Calculations
- Topic: Percent yield
- Replies: 2
- Views: 283
Re: Percent yield
First take the 42.7 g of CaCO3 and convert to moles. 42.7g x (1 mol CaCO3 / 100g CaCO3 ) = 0.4273 mol CaCO3 Then take that and do mole to mole ratio and convert from mols CO2 to grams. .4273 mol CaCO3 x ( 1 mol CO2 / 1 mol CaCO3 ) x ( 44 g CO2 / 1 mol CO2 ) = 18.8 g CO2 Then take your answer and plu...