Search found 62 matches

by 905373636
Sat Mar 14, 2020 10:09 pm
Forum: Van't Hoff Equation
Topic: ln
Replies: 9
Views: 53

Re: ln

In the same way, raising logx to 10 will cancel the log because standard log is base 10 (log10x). Ln is loge(x).
by 905373636
Sat Mar 14, 2020 10:06 pm
Forum: Experimental Details
Topic: Data
Replies: 5
Views: 23

Re: Data

it doesnt matter which order you do, as long as you can isolate an exponent x or y to get the respective rxn order. The numbers of one of the reactants in both trials should cancel out. So, as long as the variable placements are consistent it doesn't matter, right? Or is the placement not a factor ...
by 905373636
Sat Mar 14, 2020 10:05 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: A
Replies: 2
Views: 29

A

For the Arrhenius Equation, why is A approximately = 1 in most cases in this class?
by 905373636
Sat Mar 14, 2020 10:03 pm
Forum: Balancing Redox Reactions
Topic: flipping equations
Replies: 7
Views: 64

Re: flipping equations

This is all based on the equation that Ecell = Eright - Eleft and as Eleft is the oxidation cell, you 'flip' the oxidation cell.
by 905373636
Sat Mar 14, 2020 10:02 pm
Forum: Administrative Questions and Class Announcements
Topic: Final Exam Time
Replies: 13
Views: 108

Re: Final Exam Time

Even if CCLE crashes (again oof), though, the test saves every 2 minutes so we'll be good!
by 905373636
Sat Mar 14, 2020 10:01 pm
Forum: General Rate Laws
Topic: Factors Affecting k
Replies: 16
Views: 80

Re: Factors Affecting k

Vinita Saxena 2I wrote:Yes, it can change if the temperature changes, that is the only way it can change


Isn't the addition of a catalyst also a way to change it?
by 905373636
Tue Mar 10, 2020 6:00 pm
Forum: Administrative Questions and Class Announcements
Topic: Email Announcement
Replies: 8
Views: 192

Email Announcement

What does Gene Block’s announcement mean for our final in this class as gatherings of more than 100 people?
by 905373636
Mon Mar 09, 2020 1:16 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: k constants
Replies: 1
Views: 15

Re: k constants

And also then why does k = 2k2?
by 905373636
Mon Mar 09, 2020 1:15 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: k constants
Replies: 1
Views: 15

k constants

Why is 2k1k2 / k’1 equal to k (of observed rate law)? Why do these agree with one another?
by 905373636
Wed Mar 04, 2020 1:54 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Figuring out n
Replies: 15
Views: 83

Re: Figuring out n

n is the mols of electrons transferred! Make sure not to find a common multiple, then, for example if for a reduction 2 electrons are transferred whereas for an oxidation 3 electrons are transferred -> common multiple 6 when balancing equations and 6 electrons are transferred; (n=6).
by 905373636
Wed Mar 04, 2020 1:52 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: calculating K2?
Replies: 3
Views: 56

Re: calculating K2?

You find K2 by using the Vant Hoff equation you wrote down: ln K2/K1=-ΔH°/R [1/T2-1/T1] After finding K2, square root it to find the H3O+ concentration. Use the concentration to find the pH. This pH is the neutral pH at 10 degrees C. Compare that number with 7 to see if a pH of 7 is acidic or basic...
by 905373636
Wed Mar 04, 2020 1:48 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: When to use Platinum as an electrode
Replies: 4
Views: 31

Re: When to use Platinum as an electrode

If your reaction involves conductive metals like Ag and Cu, though, you do not need to involve Pt as a conductor for your cell diagram.
by 905373636
Wed Mar 04, 2020 1:46 pm
Forum: Van't Hoff Equation
Topic: Converting K back to Kc
Replies: 5
Views: 59

Re: Converting K back to Kc

What's the equation needed to convert K back to Kc? I assumed you would just rearrange the Kc to K equation, but I wanted to ask just to be sure. aren't those the same Not according to the book :( Look at the very last part of section 5J.3, it talks about converting K to Kc when using Van't Hoff eq...
by 905373636
Wed Mar 04, 2020 1:44 pm
Forum: First Order Reactions
Topic: Graph
Replies: 9
Views: 69

Re: Graph

If you write [A] vs. time for a 1st order run, though, it'll show exponential decay so make sure to have it in ln form!
by 905373636
Mon Mar 02, 2020 12:43 am
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: 6N.17
Replies: 1
Views: 32

6N.17

Why is there work done in this system, and how do we find Ecell? I keep calculating it to be 0V as the cathode and anode are reducing/oxidizing the same reaction in reverse to one another (?)
by 905373636
Sun Mar 01, 2020 11:40 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: n in Equation
Replies: 6
Views: 44

n in Equation

I'm a bit confused as to how to find n in reactions and I'm a bit confused too with what it represents.

For example,
for the reaction Mn + Ti2+ <--> Mn2+ + Ti n=2, but I'm not sure as to why.

Could someone help explain?
by 905373636
Fri Feb 28, 2020 12:29 pm
Forum: General Rate Laws
Topic: Reaction Rates
Replies: 5
Views: 48

Reaction Rates

Why are all reaction rates 'positive' if the [reactants] decreases in exchange to an increase in [products] (for a forward reaction, in example)?
by 905373636
Fri Feb 28, 2020 12:23 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Heat Death
Replies: 2
Views: 76

Heat Death

What does the eventual heat death of the universe say about its entropy and enthalpy relationship? Is all of the energy in the universe in its potential energy form?
by 905373636
Fri Feb 28, 2020 12:21 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: Diamond Reaction
Replies: 4
Views: 66

Re: Diamond Reaction

Lavelle said that the reaction from diamond to graphite was spontaneous but had a very high activation energy and would occur very slowly. Does this mean that over time, say a few trillions years, the diamond is slowly collecting enough energy to overcome the energy barrier? Or would the reaction e...
by 905373636
Fri Feb 28, 2020 12:19 pm
Forum: Biological Examples
Topic: ATP example
Replies: 6
Views: 602

Re: ATP example

MariahClark 2F wrote:Wouldn’t the reaction be exergonic since it’s giving off energy and not requiring it?


In ATP's case, yes, but not all hydrolytic reactions are exergonic -- when it requires more energy than it gives off.
by 905373636
Fri Feb 28, 2020 12:17 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Galvanic Cells
Replies: 10
Views: 49

Re: Galvanic Cells

Yes, when a battery is dead, the system has reached equilibrium -- though I'm wondering now if it's possible to 'revive' a battery or replace its galvanic cells concentration gradient?
by 905373636
Fri Feb 21, 2020 1:37 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Spontaneity
Replies: 7
Views: 75

Spontaneity

Do higher cell potentials within a cell indicate anything about the rate of the reaction or just the spontaneity?
by 905373636
Fri Feb 21, 2020 1:14 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Electrode
Replies: 4
Views: 31

Electrode

When Platinum is an electrode, as it is carrying electrons, on an atomic level is it getting reduced and oxidized continuously as electrons are passed from atom to arom
by 905373636
Fri Feb 21, 2020 12:28 pm
Forum: Balancing Redox Reactions
Topic: Oxidation number of Ozone
Replies: 10
Views: 64

Re: Oxidation number of Ozone

If you look at the lewis structure of ozone, it does have individual oxygen formal charges but the overall formal charge is 0 and there is resonance; the oxidation number of the whole molecule of ozone (not of the individual oxygen atoms that compose it) is thus 0.
by 905373636
Fri Feb 21, 2020 12:25 pm
Forum: Balancing Redox Reactions
Topic: Redox Proton Transfer
Replies: 3
Views: 27

Redox Proton Transfer

Will we ever examine proton transfer in redox reactions and how that is linked to electron transfer, as that bit has confused me in bio classes?
by 905373636
Fri Feb 21, 2020 12:24 pm
Forum: Balancing Redox Reactions
Topic: Oxidation numbers
Replies: 6
Views: 43

Re: Oxidation numbers

Kate Swertfager wrote:Are all diatomic molecules neutral charge?


Diatomic molecules of the same atom (homonuclear) should all be neutral charge.
by 905373636
Fri Feb 21, 2020 12:22 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Favorability [ENDORSED]
Replies: 1
Views: 53

Favorability [ENDORSED]

If you have three galvanic cells all linked individually with the other two, will the two with the most favorable change in Voltage react together or would there be a system mixed reaction(s)?
by 905373636
Fri Feb 21, 2020 12:19 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Voltage and Current
Replies: 2
Views: 18

Voltage and Current

How are Voltage and Current related? Will we ever see an ammeter included in diagrams in this class -- will we relate amperes and volts in an equation?
by 905373636
Sun Feb 16, 2020 11:53 am
Forum: Van't Hoff Equation
Topic: concept help
Replies: 4
Views: 48

Re: concept help

Van't Hoff relates a reaction's equilibrium constant Keq with temperature, standard enthalpy, and standard entropy -- so it'd be useful in modeling how the equilibrium constant changes due to T, S, and H changes I assume in a more definite way. [url]https://en.wikipedia.org/wiki/Van_%27t_Hoff_equati...
by 905373636
Sun Feb 16, 2020 11:46 am
Forum: Balancing Redox Reactions
Topic: skeletal equations
Replies: 3
Views: 34

Re: skeletal equations

I think it just has to do with the ways to write an equation: C is usually put at the center as it is a central atom within this compound, but the more electropositive atom is usually put at the right (C) and the more electronegative at the left (O). Those conditions conflict here, so both ways of w...
by 905373636
Sun Feb 16, 2020 11:43 am
Forum: Balancing Redox Reactions
Topic: oxidation vs reduction
Replies: 19
Views: 132

Re: oxidation vs reduction

Veronica Lu 2H wrote:Leo goes Ger [censored]
Losing electrons = oxidation
Gaining electrons= reduction


Similarly, OIL RIG helps me:

Oxidation is Loss

Reduction is Gain
by 905373636
Sun Feb 16, 2020 11:42 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Midterm Curve
Replies: 45
Views: 377

Re: Midterm Curve

Going off what happened in 14A and in his syllabus, he does not curve the midterm but a 50% in the class is a C, so in that way he does curve the final grade to help those that are close to failing. Does this mean all other grades are curved too? Like how low does an A or an A- go? Or does it not a...
by 905373636
Sun Feb 16, 2020 11:41 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Gibbs Free energy concept
Replies: 16
Views: 110

Re: Gibbs Free energy concept

The Gibbs free energy can predict the spontaneity of a reaction at different circumstances / environmental conditions. In this way, it can predict at what temperature -- for example -- a reaction becomes spontaneous if all other factors are constant.
by 905373636
Fri Feb 07, 2020 12:25 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Midterm Equations
Replies: 4
Views: 40

Midterm Equations

Should we familiarize ourselves but not memorize the equations in thermodynamics for the midterm? Or should we focus on memorizing some of them too -- ones that won't be provided on an equation sheet?
by 905373636
Fri Feb 07, 2020 12:24 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Entropy
Replies: 4
Views: 27

Re: Entropy

The more material there is capable of increasing disorder, the higher the entropy potential exists.
by 905373636
Fri Feb 07, 2020 12:22 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: state occupation of phases
Replies: 7
Views: 34

Re: state occupation of phases

Gas molecules are higher energy and occupy the entirety of the volume of a container as they 'bounce' off of one another and off of the container; it has a lot to do with the decreased density and the increased speed of the particles when they're in their gaseous phase.
by 905373636
Fri Feb 07, 2020 12:18 pm
Forum: Calculating Work of Expansion
Topic: Difference in Wirr and Wrev
Replies: 4
Views: 28

Re: Difference in Wirr and Wrev

Wrev is an ideal situation with constant Temperature; Wirr is the more realistic and non-constant Temperature scenario and thus it does less work.
by 905373636
Mon Feb 03, 2020 1:42 pm
Forum: Calculating Work of Expansion
Topic: Degeneracy and Volume
Replies: 6
Views: 48

Degeneracy and Volume

Is W2/W1 always equal to V2/V1?
by 905373636
Fri Jan 31, 2020 1:30 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Open vs. Closed Internal Energies
Replies: 3
Views: 34

Open vs. Closed Internal Energies

Today, we talked about in class that in an open system with an exothermique rxn there is expansion work being done.

If it was a closed system, is there no expansion work? Though pressure isn’t constant?
by 905373636
Fri Jan 31, 2020 1:00 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Reversible vs Irreversible formula
Replies: 4
Views: 74

Re: Reversible vs Irreversible formula

If the problem indicates that the system is under a constant pressure, then you would use the w=-P∆V equation to calculate the work done. If the problem instead indicates that the reaction is an isothermic expansion where pressure is not constant, then you would use the equation for a reversible re...
by 905373636
Fri Jan 31, 2020 12:58 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Test 1 #5
Replies: 7
Views: 80

Re: Test 1 #5

You're given pKb so you can find Kb. However, in the reaction given you need Ka because HF is an acid. Solve for Ka by using Ka*Kb=Kw, K =1*10^-14. Ka is now your equilibrium constant.Then use the given initial concentration of hydrogen fluoride, 0.12M, and complete an ice table using the Ka consta...
by 905373636
Fri Jan 31, 2020 12:44 pm
Forum: Administrative Questions and Class Announcements
Topic: Midterm
Replies: 8
Views: 70

Re: Midterm

Will it focus more on the new content than what we’ve already learned for Test 1 or just even distribution?
by 905373636
Fri Jan 31, 2020 12:43 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Ideal Gas QUestions
Replies: 8
Views: 48

Re: Ideal Gas QUestions

504999222 wrote:If the pressure goes up, would that mean the volume would go down?


Can’t pressure go up with T going up from PV=nRT with no effect on volume?
by 905373636
Fri Jan 31, 2020 12:42 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Closed vs isolated systems
Replies: 24
Views: 116

Re: Closed vs isolated systems

A bomb calorimeter would be an isolated system; a closed system would be the ‘cup’ with the external pressure image.
by 905373636
Sun Jan 26, 2020 11:49 am
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: 4B.3
Replies: 1
Views: 14

4B.3

This problem involves 982 J = 492 J + w so I calculated the answer to be 490J, but the back of the textbook says its 90 x 10^2 J. Could someone please explain if that's correct?
by 905373636
Fri Jan 24, 2020 12:33 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Ka and Kb
Replies: 10
Views: 78

Re: Ka and Kb

Bryan Chen 1H wrote:No, strong acids and bases also have Ka and Kb i think, it is just very large (and they also dissociate completely) so there's no real need to use it in problems


What, hypothetically, would be a situation that we use strong acids'/bases' Ka and/or Kb?
by 905373636
Fri Jan 24, 2020 12:30 pm
Forum: Phase Changes & Related Calculations
Topic: Steam vs. Boiling Water
Replies: 10
Views: 73

Re: Steam vs. Boiling Water

Basically, this is because steam has undergone a phase change from liquid to water vapor (vaporization). Vaporization requires a lot of energy. When steam touches your skin, it will release a lot of energy as it cools to form liquid water. Water, while at the same energy, does not have the same lat...
by 905373636
Fri Jan 24, 2020 12:27 pm
Forum: Phase Changes & Related Calculations
Topic: Phase Transition Temp.
Replies: 6
Views: 50

Phase Transition Temp.

Can someone reiterate how temperature remains constant during a phase transition? Does it then suddenly just spike/fall after the transition is complete? A bit confused just by the process of it all. How is the steam causing burns example applicable?
by 905373636
Fri Jan 24, 2020 12:25 pm
Forum: Ionic & Covalent Bonds
Topic: Carbon
Replies: 3
Views: 65

Re: Carbon

The only atoms I can think of capable of making quad bonds are certain transition metals -- 1 s bond, 2 p bonds, and 1 d bond.
by 905373636
Fri Jan 24, 2020 12:23 pm
Forum: Ideal Gases
Topic: Kc vs Kp
Replies: 43
Views: 307

Re: Kc vs Kp

The difference here just has to do with units used, though Kp will include all gases yes.
by 905373636
Sat Jan 18, 2020 11:31 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Difference between K and Q?
Replies: 11
Views: 56

Re: Difference between K and Q?

K is a fixed value for the reaction, while Q varies if the reaction is/is not yet at equilibrium and we can compare the two values to determine if the reaction is at equilibrium or not.
by 905373636
Sat Jan 18, 2020 11:29 am
Forum: General Science Questions
Topic: Body Reactions
Replies: 1
Views: 26

Body Reactions

Since the acid-base equilibria we're exploring right now is dependent on Kw, at 25 degrees Celsius, how different are reactions with organic life such as the human body where regular temperatures are completely different (37 degrees C for human body).
by 905373636
Sat Jan 18, 2020 11:22 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Quick way
Replies: 7
Views: 54

Re: Quick way

The example Dr. Lavelle gave in class was if you added Helium to a reaction occurring within a sealed container. While the pressure of the reaction is increasing, it has no effect on the equilibrium because adding gas doesn't have any effect on the actual concentration of either the products or rea...
by 905373636
Sat Jan 18, 2020 11:19 am
Forum: Ideal Gases
Topic: Topics on Test 1
Replies: 37
Views: 268

Re: Topics on Test 1

At this point, everything we've done in lecture which seems to cover both outline 1 and 2.
by 905373636
Sat Jan 18, 2020 11:15 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Tips for Test
Replies: 23
Views: 176

Re: Tips for Test

The video modules are available on the class website too and those really helped me over winter break, so use those too to study and review!
by 905373636
Mon Jan 13, 2020 12:21 pm
Forum: General Science Questions
Topic: Salt Dissolving in Water
Replies: 3
Views: 31

Re: Salt Dissolving in Water

Tai Metzger 3K wrote:I hope I can help you resolve this haunting question. I believe that it is a physical reaction because no bonds are broken.


I thought, though, that salt dissolving in water meant that the ions bonds were broken -- making the solution homogeneous (?)
by 905373636
Thu Jan 09, 2020 4:14 pm
Forum: Administrative Questions and Class Announcements
Topic: Saying Thank You to Dr. Lavelle
Replies: 275
Views: 117607

Re: Saying Thank You to Dr. Lavelle

Dear Dr. Lavelle,

The quarter just started, but you've already introduced us to so many resources and have made access to help readily available. With all my other classes, this constant makes me so much less stressed.

Thank you so much!
by 905373636
Thu Jan 09, 2020 4:11 pm
Forum: General Science Questions
Topic: Salt Dissolving in Water
Replies: 3
Views: 31

Salt Dissolving in Water

This is a question that has haunted me for many years: Is salt (NaCl) dissolving in water a physical or chemical change? In water the ions are technically separated as the sheer [H2O] is powerful enough to separate them (the amount of ion-dipole interactions is more and stronger than the ionic bonds...
by 905373636
Thu Jan 09, 2020 4:05 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5.57
Replies: 1
Views: 25

5.57

For 5.57 of the Focus 5 Exercises, does anyone know how to complete the last part about finding the [NO]? We're given the initial [] of one reactant and the equilibrium [] of one product, but there's 2 reactants and 2 products and that's two unknowns.
by 905373636
Thu Jan 09, 2020 4:02 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5.39
Replies: 1
Views: 25

5.39

5.39 on the Focus 5 Exercises involves Table E.2, but I can't seem to find that table in my textbook. Does anyone else have this problem?
by 905373636
Thu Jan 09, 2020 3:59 pm
Forum: Ideal Gases
Topic: K value
Replies: 14
Views: 84

Re: K value

It's also important to remember that the significance of K is only considered strong when it is either >10^3 (strongly favor products) or <10^-3 (strongly favor reactants). Anything in between those two values still favors one side or the other (except for the rare circumstance at 1), but isn't cons...
by 905373636
Mon Jan 06, 2020 10:24 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5I.23
Replies: 1
Views: 34

5I.23

Has anyone solved 5I.23? It involves CO(g) + 3H2(g) -><- CH4(g) + H2O(g) and we know the initial [] of CO is 0.2 mol/L and H2 is 0.3 mol/L (the products are 0) and that [CH4] at equilibrium is 0.478, but we don't know anything about [H2O] at equilibrium. How do we solve for Kc with that unknown? I t...

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