Search found 35 matches

by Melody P 2B
Thu Mar 14, 2019 5:39 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Concentration Cells
Replies: 1
Views: 50

Re: Concentration Cells

Concentration cells contain the same components but at differing concentrations. So, the anode and cathode are the same in terms of what they are, but not their concentrations. For example, in class Lavelle used 0.1 M of Ag+ and 1 M of Ag+
by Melody P 2B
Mon Mar 11, 2019 3:00 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Determining the Magnitude of K
Replies: 3
Views: 58

Re: Determining the Magnitude of K

In lector today (3/11) Dr. Llavelle briefly spoke about what determines the magnitude of K, can someone clarify what he meant by this? It was toward the end of the lecture so I wasn't able to write everything down. Thank you. Are you referring to capital K(equilibrium)? or lowercase k (rate constan...
by Melody P 2B
Mon Mar 11, 2019 2:51 pm
Forum: First Order Reactions
Topic: Half-life Clarification
Replies: 5
Views: 98

Re: Half-life Clarification

Yes, because the half life equations are derived from the integrated rate laws. And the integrated rate laws differ in terms of reaction order.
slide1-l.jpg


This should help!
by Melody P 2B
Thu Mar 07, 2019 4:15 pm
Forum: Zero Order Reactions
Topic: Concentration independent of the rate
Replies: 4
Views: 72

Concentration independent of the rate

When the concentration of a reactant is independent of the rate does that mean it's zero order? And how would we be able to tell given a table of initial rates/concentrations?
by Melody P 2B
Wed Mar 06, 2019 6:50 pm
Forum: Zero Order Reactions
Topic: Slope = -k
Replies: 3
Views: 70

Re: Slope = -k

This kind of helps answer your question.

Differential-and-Integrated-Rate-Laws1.pdf
(508.57 KiB) Downloaded 12 times
by Melody P 2B
Wed Mar 06, 2019 6:46 pm
Forum: General Rate Laws
Topic: rate laws
Replies: 3
Views: 58

Re: rate laws

I think the difference is just that the Differential Rate Law uses derivatives, but we want to make the analysis easier/"better" so to get rid of the derivatives we integrate. So, the Differential Rate Law expresses the rate of the reaction as a function of change in concentration over tim...
by Melody P 2B
Fri Mar 01, 2019 10:26 am
Forum: Balancing Redox Reactions
Topic: Strength of reducing agent
Replies: 10
Views: 228

Re: Strength of reducing agent

Chase Yonamine 1J wrote:The smallest (more negative) Reduction potential is a stronger reducing agent


Why is that?
by Melody P 2B
Fri Mar 01, 2019 10:25 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Does anyone know if test 2 will be curved?
Replies: 15
Views: 310

Re: Does anyone know if test 2 will be curved?

Most likely not, since the first test wasn't. I would not expect test 2 to be curved. :(
by Melody P 2B
Thu Feb 28, 2019 4:54 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Pt inert electrode
Replies: 9
Views: 205

Re: Pt inert electrode

Would you add Pt(s) to both sides?
by Melody P 2B
Mon Feb 25, 2019 6:38 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Difference in values
Replies: 2
Views: 47

Re: Difference in values

E cell refers to electrode potential of a cell.

Eo cell refers to standard electrode potential where electrode potential is measured at 1 atmosphere pressure, 1 molar solution at 25° C.(aka standard conditions)
by Melody P 2B
Sun Feb 24, 2019 11:20 pm
Forum: Balancing Redox Reactions
Topic: Test #2
Replies: 9
Views: 192

Re: Test #2

Lavelle mentioned in lecture on Friday that Test 2 would cover Gibbs Free Energy up until what the lecture covered Friday.
by Melody P 2B
Thu Feb 21, 2019 7:46 pm
Forum: Balancing Redox Reactions
Topic: 6K.1 7th Edition
Replies: 1
Views: 43

6K.1 7th Edition

H+ + Cr2O72-+C2H5OH ----> Cr3+ + H2O

The oxidized reaction is C2H5OH ---> C2H4O

The solutions manual says C is oxidized from 2- to 1- but when I do the math I get from 2- to 1+ , what am I doing wrong?
by Melody P 2B
Thu Feb 21, 2019 6:18 pm
Forum: Balancing Redox Reactions
Topic: Oxidation States
Replies: 10
Views: 151

Re: Oxidation States

This may be of some help!!! It can also be found on the course website
Balancing_Redox_Reactions_Acidic_Conditions.pdf
(101.57 KiB) Downloaded 18 times
by Melody P 2B
Mon Feb 11, 2019 9:23 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Irreversible Expansions and Work
Replies: 2
Views: 71

Re: Irreversible Expansions and Work

Also, take a look at these two diagrams uploaded on the class website!!
Reversible_Expansion.pdf
(62.74 KiB) Downloaded 12 times
Irreversible_Expansion.pdf
(38.14 KiB) Downloaded 13 times
by Melody P 2B
Mon Feb 11, 2019 9:18 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Irreversible Expansions and Work
Replies: 2
Views: 71

Re: Irreversible Expansions and Work

You've got it backwards, reversible expansion does more work. And will always do more work, this is because they tend to push against more external pressure and are slow processes. Reversible processes are also ideal situations where no energy is wasted. Irreversible expansion is spontaneous/ occurs...
by Melody P 2B
Mon Feb 11, 2019 9:01 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: When to use C=5/2R or C=3/2R
Replies: 7
Views: 1667

Re: When to use C=5/2R or C=3/2R

404982241 wrote:use the 5/2 when pressure is constant.
use 3/2 when volume is constant.

a great example is problem 8.31 in the 6th edition


Would these only be used when working with an ideal gas?
by Melody P 2B
Mon Feb 11, 2019 8:58 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Midterm [ENDORSED]
Replies: 49
Views: 1374

Re: Midterm [ENDORSED]

I've never had Lavelle before and I was wondering whether the questions on midterms/finals are mostly math based/problem solving or are there conceptual questions asked as well? They're mostly math based/problem solving but there are still conceptual questions, they're just worth less points./A lot...
by Melody P 2B
Fri Feb 08, 2019 6:52 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: Lecture notes 2/8/19
Replies: 3
Views: 94

Lecture notes 2/8/19

I missed lecture because I had a midterm at the time, would anyone be open to sharing their notes? Please and thanks. :)
by Melody P 2B
Thu Feb 07, 2019 8:14 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: q= -w
Replies: 8
Views: 151

q= -w

What exactly is meant by q=-w or -q=w ?
by Melody P 2B
Tue Feb 05, 2019 3:29 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Midterm [ENDORSED]
Replies: 49
Views: 1374

Re: Midterm [ENDORSED]

I've never had Lavelle before and I was wondering whether the questions on midterms/finals are mostly math based/problem solving or are there conceptual questions asked as well?
by Melody P 2B
Tue Feb 05, 2019 3:25 pm
Forum: Calculating Work of Expansion
Topic: Difference between L.atm and Joules
Replies: 2
Views: 79

Re: Difference between L.atm and Joules

Yes, you'll always have to multiply the answer in by 101.33 J to convert into J because as previously mentioned work is typically expressed in Joules. Also, my TA was uncertain as to whether this conversion will be on our equations sheet so that's something to keep in mind.
by Melody P 2B
Sun Feb 03, 2019 2:43 pm
Forum: Calculating Work of Expansion
Topic: Finding W Equations
Replies: 1
Views: 72

Re: Finding W Equations

Hi! So the reason we ended up back with w= -P\Delta V is because we were working with the DEFINITE integral which is basically V FINAL -V INITIAL which is just \Delta V Keep in mind though that this is only when pressure is constant. The derivative/integral was used for the reversible reaction examp...
by Melody P 2B
Wed Jan 30, 2019 6:16 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Thermo Test/Midterm
Replies: 9
Views: 191

Re: Thermo Test/Midterm

Most likely not, my TA also included drawing the lewis structures to account for bonds as one of the steps when calculating using bond enthalpies.
by Melody P 2B
Tue Jan 29, 2019 3:50 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: enthalpy
Replies: 4
Views: 67

Re: enthalpy

If you're a more visual person picture the image Lavelle presented in class of a mountain. There was a blue line and a red line, both lines started and ended in the same place. However, the path each line took was different! But because enthalpy is a state property that path doesn't matter because b...
by Melody P 2B
Wed Jan 23, 2019 5:17 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: ICE boxes
Replies: 5
Views: 90

Re: ICE boxes

Yes! They can be, ICE tables help organize what you are given to solve equilibrium problems.
by Melody P 2B
Tue Jan 22, 2019 3:22 pm
Forum: Administrative Questions and Class Announcements
Topic: Homework for Week 3
Replies: 5
Views: 150

Re: Homework for Week 3

Week 3 HW should just be problems concerning Acids and Bases.
by Melody P 2B
Tue Jan 22, 2019 3:17 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Ka and Kb
Replies: 2
Views: 51

Re: Ka and Kb

I'm certain that the Ka and Kb values will be given, we may be given pKa or pKb, but that works just as well because if we know the pKa or pKb value you can just take the antilog to find the Ka or Kb value.
by Melody P 2B
Fri Jan 18, 2019 7:07 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Test 1
Replies: 6
Views: 153

Re: Test 1

Will topics not discussed in lecture, but discussed in the reading be on the test?
by Melody P 2B
Fri Jan 18, 2019 7:04 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Weak Acid & Salt
Replies: 4
Views: 71

Weak Acid & Salt

I just want to make sure I understand something, for the example we did in class today: Calculate the pH of solution with 0.100 M HNO2 and 0.15 M KNO2, Ka= 4.3x10^-4 The chemical equation is: HNO2(aq) + H2O (l) (eq. arrows) NO2- + H3O+ because in the chemical equation (NO2+) + (K-) + (HNO2) (eq. arr...
by Melody P 2B
Thu Jan 17, 2019 1:54 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Test 1
Replies: 6
Views: 153

Test 1

How many questions should we expect on the first test Week 3?
by Melody P 2B
Mon Jan 14, 2019 5:56 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Acids and Bases
Replies: 7
Views: 127

Re: Acids and Bases

Then is there no way to determine whether an acid or base is strong by just looking at the compound itself? It's just memorization?
by Melody P 2B
Sun Jan 13, 2019 4:30 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Result of Only Adding One of the Reactants
Replies: 4
Views: 50

Re: Result of Only Adding One of the Reactants

Then, if you were to remove some reactant would the reaction shift left? Towards the reactants to compensate for the loss?
by Melody P 2B
Thu Jan 10, 2019 4:11 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Explaining Q<K and Q>K [ENDORSED]
Replies: 7
Views: 163

Re: Explaining Q<K and Q>K [ENDORSED]

So, when Q<K it just means the reaction isn't at equilibrium, but before it right? Because there are more reactants than products, so in order to reach K the reaction will proceed forward. And when Q>K the reaction isn't at equilibrium, but after it? Because there are more products in the product/re...
by Melody P 2B
Tue Jan 08, 2019 4:01 pm
Forum: Ideal Gases
Topic: Memorization
Replies: 12
Views: 361

Re: Memorization

I have a follow up question regarding memorization, I did not take 14A with Lavelle but my previous prof made us memorize some more obscure compounds. Could the same be said of Lavelle?

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