Search found 52 matches
- Sat Mar 14, 2020 5:58 pm
- Forum: Ideal Gases
- Topic: 5% Rule
- Replies: 6
- Views: 598
Re: 5% Rule
The five percent rule is used in ICE tables. If the x value you get is 5% or less than the initial then you can ignore it. I believe that if the K is 10^-3 or less you can usually make this assumption.
- Sat Mar 14, 2020 5:55 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: What was your favorite chem topic?
- Replies: 137
- Views: 11371
Re: What was your favorite chem topic?
I think it'd have to be equilibrium. For some reason ICE tables are so satisfying to me.
- Sat Mar 14, 2020 5:55 pm
- Forum: Student Social/Study Group
- Topic: Final Jitters
- Replies: 457
- Views: 374501
Re: Final Jitters
I just like to practice a lot. At the end of the day it's just one test one quarter out of one year here. At the end of the day, everything will work out fine. You've done your best.
I hope this helps. Good luck!
I hope this helps. Good luck!
- Sat Mar 14, 2020 5:53 pm
- Forum: Administrative Questions and Class Announcements
- Topic: final exam - question
- Replies: 6
- Views: 694
Re: final exam - question
I think he just sent out an email about the logistics. It'll be submitted on ccle.
- Sat Mar 14, 2020 5:51 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Saying Thank You to Dr. Lavelle
- Replies: 490
- Views: 567230
Re: Saying Thank You to Dr. Lavelle
Dr. Lavelle,
All of your extra resources and extra hours helped me so much!
Stay safe, and thank you for the quarter :)
All of your extra resources and extra hours helped me so much!
Stay safe, and thank you for the quarter :)
- Mon Mar 09, 2020 1:00 am
- Forum: General Rate Laws
- Topic: Difference between each order of reaction
- Replies: 3
- Views: 333
Re: Difference between each order of reaction
It's based on the concentration not the amount. I'm also unsure why the overall reaction number the sum of all individual order reactions though in multiple reactions.
- Mon Mar 09, 2020 12:56 am
- Forum: Student Social/Study Group
- Topic: Final Exam Review
- Replies: 4
- Views: 477
Final Exam Review
Does anyone know if there's a final exam review held by the UAs like the pizzaroll review and does anyone know when and where that will be?
- Mon Mar 09, 2020 12:54 am
- Forum: Second Order Reactions
- Topic: [A] v. Time
- Replies: 27
- Views: 1225
Re: [A] v. Time
It's linear for second order. Does anyone know when it wouldn't be linear?
- Mon Mar 09, 2020 12:53 am
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: gibbs free energy
- Replies: 15
- Views: 870
Re: gibbs free energy
It's the energy associated with a thermodynamic reaction that is available to do work.
- Mon Mar 09, 2020 12:52 am
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Ecell
- Replies: 5
- Views: 369
Re: Ecell
Ecello or Ecell naught is just in standard conditions.
- Sun Mar 01, 2020 10:48 pm
- Forum: Balancing Redox Reactions
- Topic: Acidic vs. Basic Solutions
- Replies: 8
- Views: 667
Re: Acidic vs. Basic Solutions
I think it's almost the same but in acidic reactions H+ is used to balance equations and in basic reactions OH- is used to balance equations.
- Sun Mar 01, 2020 10:43 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: when to use K or Q
- Replies: 18
- Views: 1117
Re: when to use K or Q
Use Q when the reaction is not at equilibrium.
- Sun Mar 01, 2020 10:41 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Cathode/Right & Anode/Left
- Replies: 7
- Views: 1073
Re: Cathode/Right & Anode/Left
You can remember that the cathode is always reduction and the anode is always oxidation with this trick: "red cat" and "an ox" if that's helpful.
- Sun Mar 01, 2020 10:37 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: N value
- Replies: 7
- Views: 487
Re: N value
You just half to make sure that the number of electrons cancel out in both of the half reactions. But to answer your question yes it would be 2.
- Sun Mar 01, 2020 10:36 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: Kinetics in Test 2?
- Replies: 13
- Views: 828
Re: Kinetics in Test 2?
So is test two only on the second page of outline 4 and all of outline 5?
- Fri Feb 21, 2020 1:26 pm
- Forum: General Science Questions
- Topic: What are Workshops?
- Replies: 10
- Views: 894
Re: What are Workshops?
I go to both workshops and step ups and it's kind of the same. You just work through practice problems in both. In some workshops though worksheets are given out which are really helpful.
- Fri Feb 21, 2020 1:24 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Voltage and Current
- Replies: 2
- Views: 165
Re: Voltage and Current
Current is the rate of flow of electric charge. Voltage is the potential difference in charge of two points in an electric field. So essentially the relationship between voltage and current is that voltage causes current in a sense.
- Fri Feb 21, 2020 1:18 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Ph
- Replies: 8
- Views: 374
Re: Ph
I've always been told in peer learning sessions that a given pH is the pH when the system is at equilibrium.
- Fri Feb 21, 2020 1:16 pm
- Forum: Balancing Redox Reactions
- Topic: Redox Proton Transfer
- Replies: 3
- Views: 208
Re: Redox Proton Transfer
Wouldn't the element change if a proton was lost?
- Fri Feb 21, 2020 1:13 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Voltage of 0
- Replies: 3
- Views: 247
Re: Voltage of 0
When the galvanic cell has a voltage of zero the current stops meaning the system is in equilibrium.
- Mon Feb 17, 2020 4:47 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Open Systems
- Replies: 15
- Views: 893
Re: Open Systems
I think most equations can. Most of the time though an open system is to be considered at constant pressure though.
- Mon Feb 17, 2020 4:46 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Cv vs Cp
- Replies: 17
- Views: 990
Re: Cv vs Cp
Cv is used when there's constant volume and Cp is used when there's constant pressure.
- Tue Feb 11, 2020 2:17 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: how to find a heat capacity when not given
- Replies: 3
- Views: 188
Re: how to find a heat capacity when not given
Usually there's information you can use to get there and then use q=nC(deltaT). A lot of the TA's and UA's also warn that you can usually use PV=nRT to get values you need that don't have yet.
- Tue Feb 11, 2020 2:14 pm
- Forum: Student Social/Study Group
- Topic: set up of the midterm
- Replies: 4
- Views: 321
Re: set up of the midterm
I haven't had a class with Lavelle but I think it might be kinda like the tests. Like there are questions with like different parts under it which are worth different points. I was told to look over the Pizza Roll review to get a good representation, but of course that review doesn't have every last...
- Tue Feb 11, 2020 2:11 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Constant R
- Replies: 15
- Views: 1081
Re: Constant R
You just have to pay attention to the units of each. Just make sure your calculations cancel out units so you end up with the units you want when you've finished all of your calculations.
- Tue Feb 11, 2020 12:13 am
- Forum: Phase Changes & Related Calculations
- Topic: Work (w)
- Replies: 8
- Views: 375
Re: Work (w)
Work is dependent on the path taken. If you're on a football field and you push a sled to the 50 yard line, then you go back to the 30 yard line you do more work than someone who just pushes a sled to the 30 yard line, even though you end up in the same spot.
- Tue Feb 11, 2020 12:09 am
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: delta U = q + w
- Replies: 6
- Views: 414
Re: delta U = q + w
I think all of it is in terms of the system. So if the system is doing work than work is positive.
- Tue Feb 11, 2020 12:05 am
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Go=0
- Replies: 7
- Views: 413
Re: Go=0
Gibb's free energy is at zero when the reaction is at equilibrium.
- Mon Feb 10, 2020 11:58 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Midterm grading
- Replies: 8
- Views: 450
Re: Midterm grading
I think they have assigned problems that they each have to grade.
- Mon Feb 10, 2020 11:58 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: isothermal
- Replies: 2
- Views: 93
Re: isothermal
Yes, which means that q=-w or -w=q
- Mon Feb 10, 2020 1:27 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: State Function
- Replies: 7
- Views: 481
Re: State Function
Since it is a state function it is not path dependent. This is why we can use Hess's law, because the pathway doesn't matter just the end results.
- Mon Feb 10, 2020 1:25 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: q rev
- Replies: 9
- Views: 344
Re: q rev
the subscript rev just signifies that the reaction is reversible.
- Mon Feb 10, 2020 1:22 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Spontaneous vs Favorable
- Replies: 8
- Views: 467
Re: Spontaneous vs Favorable
A favorable reaction is when energy is released, while a spontaneous reaction is when Gibbs free energy is negative.
- Mon Feb 10, 2020 1:21 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Stability and Bond Enthalpy
- Replies: 3
- Views: 202
Re: Stability and Bond Enthalpy
The bond enthalpy is the amount of energy needed to break the bond. So the tiger the bond enthalpy the more energy needed meaning more stable.
- Mon Feb 10, 2020 1:20 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: q=CΔT
- Replies: 5
- Views: 333
Re: q=CΔT
Yes you wouldn't need to include mass of moles if they're asking for the heat energy of the calorimeter or the heat capacity of the calorimeter.
- Mon Feb 10, 2020 1:13 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: Using Cv and Cp
- Replies: 4
- Views: 257
Using Cv and Cp
When calculating entropy do we always use Cv for constant volume and Cp for constant pressure?
- Sun Feb 09, 2020 12:25 am
- 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: Going from delta S to delta H
- Replies: 2
- Views: 116
Going from delta S to delta H
What is the relationship from going from delta S to delta H? Like if you had delta S could you use it to calculate delta H as a state function?
- Sun Jan 26, 2020 9:21 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3642249
Re: Post All Chemistry Jokes Here
Are you made of copper and tellurium? Because you're CuTe.
- Sun Jan 26, 2020 9:16 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 5% Rule
- Replies: 9
- Views: 359
5% Rule
If I make the assumption because K is less than 10^-3, but the x value is less than 5% do I have to go back and use the quadratic formula to calculate x?
- Sun Jan 26, 2020 9:14 pm
- Forum: Student Social/Study Group
- Topic: Office Hours
- Replies: 5
- Views: 363
Re: Office Hours
I haven't. But the UA sessions can be very helpful!
- Sun Jan 26, 2020 9:11 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3642249
Re: Post All Chemistry Jokes Here
This is hard. All the funny chemistry jokes argon >:)
- Sun Jan 26, 2020 9:11 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3642249
Re: Post All Chemistry Jokes Here
Sb is antimony on the periodic table and how I remember it is Susan B Anthony >:)
- Sun Jan 19, 2020 10:19 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: ice table/quadratic
- Replies: 6
- Views: 291
Re: ice table/quadratic
If you get two positive values you should plug them both back in. If you subtract the value of x from the initial and get a negative value than use the other value of x.
- Sun Jan 19, 2020 10:13 pm
- Forum: Ideal Gases
- Topic: Using PV=nRT
- Replies: 7
- Views: 220
Re: Using PV=nRT
You would need to use this equation if you needed to convert mols to pressure.
- Sun Jan 19, 2020 10:10 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Effect of increasing pressure on reactions
- Replies: 6
- Views: 275
Effect of increasing pressure on reactions
Can someone explain to me what happens if you increase pressure on a reaction? Increasing pressure decreases volume so wouldn't products be favored? From my notes I have that increasing pressure doesn't favor products or reactants.
- Sun Jan 19, 2020 4:20 pm
- Forum: Calculating the pH of Salt Solutions
- Topic: Adding an Acid or Base in Water
- Replies: 3
- Views: 217
Adding an Acid or Base in Water
If someone were to add 1.0x10^-9 mol of HCL to water than why is it that the pH of the water doesn't change that much? Lavelle talked about this in lecture but I'm not sure I fully understand.
- Sun Jan 19, 2020 4:15 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Reaction Shifts Left or Right
- Replies: 15
- Views: 603
Re: Reaction Shifts Left or Right
In this reaction heat is on the product side of the reaction. So when you increase the temperature(increase heat) you increase the amount of product. The reaction will shift towards the reactants or shift left.
- Sun Jan 12, 2020 10:38 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Concentration
- Replies: 6
- Views: 248
Re: Concentration
The units aren't used because molarity isn't considered over an amount of time. K is a constant so time is not considered.
- Sun Jan 12, 2020 10:21 pm
- Forum: Ideal Gases
- Topic: Topics on Test 1
- Replies: 37
- Views: 1406
Re: Topics on Test 1
I heard it was going to be on objectives from outline one for sure, but I was told it may not be all of the objectives in outline 2 if all the material isn't covered in lecture.
- Sun Jan 12, 2020 9:51 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Values of K and Meaning
- Replies: 3
- Views: 199
Values of K and Meaning
If K>1 this means there are more products at equilibrium and if K<1 this means there are more reactants at equilibrium. But there is also the values discussed in lecture where if K>10^3 products are strongly favored and if K<10^-3 reactants are favored. What's the difference between there being more...
- Sun Jan 12, 2020 9:40 pm
- Forum: Student Social/Study Group
- Topic: Peer Learning Sessions in Young Hall
- Replies: 5
- Views: 348
Peer Learning Sessions in Young Hall
When do the Peer Learning Sessions in Young Hall start and will different material be presented in different days of the week?
- Sun Jan 12, 2020 9:35 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: 5% rule
- Replies: 12
- Views: 21785
Re: 5% rule
The five percent rule allows you to get out of using the quadratic formula when doing ice tables. Be sure to check if the x value you get is smaller than 5% of the initial value to get out of using the quadratic formula