Search found 45 matches
- Fri Mar 16, 2018 9:00 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: 9.1
- Replies: 5
- Views: 892
Re: 9.1
There is a negative because of the fact that the heat is leaving your body and going into the surroundings.
- Fri Mar 16, 2018 8:58 pm
- Forum: *Nucleophiles
- Topic: Functional Groups
- Replies: 3
- Views: 1256
Re: Functional Groups
I think just being able to identify the different functional groups is all that is expected of us.
- Fri Mar 16, 2018 8:58 pm
- Forum: General Rate Laws
- Topic: Negative 1/a
- Replies: 8
- Views: 1056
Re: Negative 1/a
Concentration of reactants decreases.
- Fri Mar 09, 2018 4:30 pm
- Forum: General Rate Laws
- Topic: Rate Constant k
- Replies: 6
- Views: 774
Re: Rate Constant k
The rate constant is an experimentally determined value for a specific reaction at a specific temperature. It essentially tells you the instantaneous rate of change.
- Fri Mar 09, 2018 4:28 pm
- Forum: General Rate Laws
- Topic: Division in Rate Law
- Replies: 3
- Views: 941
Re: Division in Rate Law
The answer should be zero, since you would have a negative exponent in the denominator, and a positive exponent in the numerator, so when added together they should equal zero.
- Fri Mar 09, 2018 4:24 pm
- Forum: First Order Reactions
- Topic: k' in Pseudo-First-Order Rate Laws
- Replies: 4
- Views: 1509
Re: k' in Pseudo-First-Order Rate Laws
k' just means a different rate constant. This is because we are treating a second order reaction as if it's a first order reaction, so it must have a different rate constant.
- Fri Mar 02, 2018 7:14 pm
- Forum: First Order Reactions
- Topic: Pseudo First Order Reaction
- Replies: 5
- Views: 1808
Re: Pseudo First Order Reaction
All of the concentrations except for one, of the reactants are super high in a pseudo first order reaction. This is done in order to keep the reactants essentially constants.
- Fri Mar 02, 2018 7:13 pm
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: Quiz 3
- Replies: 6
- Views: 798
Re: Quiz 3
Yes.
- Fri Mar 02, 2018 7:12 pm
- Forum: General Rate Laws
- Topic: Determining Order [ENDORSED]
- Replies: 8
- Views: 994
Re: Determining Order [ENDORSED]
You have to to experiment by looking at how much the rate changes from your initial amount. If it changes by double it is a first order. If it quadruples it is second order. The important thing to note is that it has nothing to do with the coefficients of your chemical equation.
- Fri Feb 23, 2018 1:07 am
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Nernst Equation to find pH
- Replies: 6
- Views: 9986
Re: Nernst Equation to find pH
Find the concentration of H+ ions, and then take the negative log of that concentration.
- Fri Feb 23, 2018 1:06 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Inert Electrodes
- Replies: 4
- Views: 562
Re: Inert Electrodes
Draw the salt bridge to show that you have finished the oxidation portion of the reaction, and that you are moving onto the reduction portion.
- Fri Feb 23, 2018 1:05 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Cell diagram
- Replies: 4
- Views: 553
Re: Cell diagram
I prefer to go in the order of what is happening. So with oxidation I start off with some kind of solid and then move to the positive ion. With reduction I start with the positive ion and then move to the solid.
- Fri Feb 16, 2018 7:21 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Anode/ Cathode
- Replies: 6
- Views: 784
Re: Anode/ Cathode
I believe that the template usually has the anode on the left, but I don't think it physically needs this to work.
- Fri Feb 16, 2018 7:19 pm
- Forum: Balancing Redox Reactions
- Topic: Salt Bridges
- Replies: 14
- Views: 1262
Re: Salt Bridges
Salt bridges allow electron transfer between two solutions.
- Fri Feb 16, 2018 7:19 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Equilibrium
- Replies: 4
- Views: 436
Re: Equilibrium
I think that the current keeps going. But there is no change in current.
- Wed Feb 07, 2018 11:58 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Calculating Potential Difference between Electrodes
- Replies: 3
- Views: 433
Re: Calculating Potential Difference between Electrodes
No that makes sense, because you can't actually calculate anything when it's at zero.
- Wed Feb 07, 2018 11:57 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Half Reactions
- Replies: 6
- Views: 659
Re: Half Reactions
It shouldn't matter, because when you add them together you always end up with the original reaction.
- Wed Feb 07, 2018 11:54 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Will dissolving a salt in water affect the entropy of the water?
- Replies: 3
- Views: 1386
Re: Will dissolving a salt in water affect the entropy of the water?
Wait new thought, if you're taking a solid and adding it to water, then the entropy would increase, because you now you have an aqueous solution.
- Wed Feb 07, 2018 11:53 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Will dissolving a salt in water affect the entropy of the water?
- Replies: 3
- Views: 1386
Re: Will dissolving a salt in water affect the entropy of the water?
If you're adding particles wouldn't that increase the entropy?
- Fri Feb 02, 2018 7:13 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Van Hoff Equation
- Replies: 3
- Views: 437
Re: Van Hoff Equation
It probably can't hurt, but you shouldn't need to know it.
- Fri Feb 02, 2018 7:12 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Entropy [ENDORSED]
- Replies: 5
- Views: 1982
Re: Entropy [ENDORSED]
Any reaction that has a negative delta G.
- Fri Feb 02, 2018 7:11 pm
- Forum: Calculating Work of Expansion
- Topic: Free expansion and irreversible expansion
- Replies: 2
- Views: 422
Re: Free expansion and irreversible expansion
I believe free expansion is when there is no opposing pressure on a system, so it is allowed to expand without doing any work. Irreversible expansion is what allows for the maximum amount of work.
- Tue Jan 23, 2018 4:50 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: system of vacuum
- Replies: 4
- Views: 559
Re: system of vacuum
I think that this question is flawed, because it presupposes that a vacuum is a system. But a vacuum is simply nothing, so it seems wrong to think of it a system.
- Tue Jan 23, 2018 4:48 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Isolated system
- Replies: 8
- Views: 985
Re: Isolated system
No, an isolated system cannot be affected in any way by the surroundings.
- Tue Jan 23, 2018 4:47 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Entropy of an Isolated System
- Replies: 4
- Views: 808
Re: Entropy of an Isolated System
One way of thinking of entropy is simply a measure of energy that becomes unusable. If we know that there is a fixed amount of usable energy in any given system, then it follows that there is also a fixed amount of entropy in a given system as well. If there is a fixed amount it must at some point r...
- Thu Jan 18, 2018 6:05 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Reversible, Irreversible
- Replies: 4
- Views: 441
Re: Reversible, Irreversible
Reversible means that the two pressures are essentially equal and that an infinitesimal change can cause expansion. Irreversible is when no such change can occur.
- Thu Jan 18, 2018 6:03 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Adiabatic [ENDORSED]
- Replies: 8
- Views: 975
Re: Adiabatic [ENDORSED]
It would be a process where q=0 and w=some number.
- Thu Jan 18, 2018 6:02 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Most Stable Form
- Replies: 3
- Views: 884
Re: Most Stable Form
I always think of things in terms of potential energy. Whatever formation has the lowest potential energy should be the most stable.
- Sun Jan 14, 2018 2:06 pm
- Forum: Phase Changes & Related Calculations
- Topic: Why can state properties be added?
- Replies: 11
- Views: 1222
Re: Why can state properties be added?
State properties can be added because only specific points matter when looking at the states. The paths that are taken don't matter, so we can add the relevant points and forget the rest.
- Sun Jan 14, 2018 2:05 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Calorimeter
- Replies: 10
- Views: 1011
Re: Calorimeter
It is a way of measuring a specific form of energy.
- Sun Jan 14, 2018 2:03 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Systems
- Replies: 7
- Views: 875
Re: Systems
The ocean.
- Thu Dec 07, 2017 7:56 pm
- Forum: Lewis Acids & Bases
- Topic: 12.13
- Replies: 5
- Views: 865
Re: 12.13
I would think you should ignore the d orbital. So just write Ag+.
- Thu Dec 07, 2017 7:55 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Endothermic v. Exothermic Reactions
- Replies: 9
- Views: 2569
Re: Endothermic v. Exothermic Reactions
In endothermic energy is being consumed, in other words it requires energy in order to function. In an exothermic reaction energy is being released. Often times, exothermic reactions are used to power endothermic reactions.
- Fri Nov 24, 2017 12:28 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Expanded octet
- Replies: 6
- Views: 653
Re: Expanded octet
Just look to see if the atom has access to a d-orbital, that’s the biggest clue you will get!
- Fri Nov 24, 2017 12:26 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Partial Pressure or Concentration
- Replies: 3
- Views: 403
Re: Partial Pressure or Concentration
I’m curious about this as well!
- Wed Nov 08, 2017 8:06 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Unpaired Electrons [ENDORSED]
- Replies: 7
- Views: 1022
Re: Unpaired Electrons [ENDORSED]
When you are adding your electrons to their orbitals, remember to put an electron in each orbital before you fill your orbitals.
- Wed Nov 08, 2017 8:02 pm
- Forum: Balancing Chemical Reactions
- Topic: Net Moles of Gas
- Replies: 5
- Views: 559
Re: Net Moles of Gas
Why do we assume that the H2O is a liquid?
- Tue Oct 31, 2017 8:01 pm
- Forum: Trends in The Periodic Table
- Topic: Effective Nuclear Charge [ENDORSED]
- Replies: 4
- Views: 1606
Re: Effective Nuclear Charge [ENDORSED]
Effective nuclear charge decreases as you go down a group because you are adding orbitals as you go down, in other words the electron is being added into a new orbital that is farther away from the nucleus. This increases the shielding because there are more electrons in between the nucleus and the ...
- Tue Oct 31, 2017 7:50 pm
- Forum: Electronegativity
- Topic: Electronegativity [ENDORSED]
- Replies: 5
- Views: 728
Re: Electronegativity [ENDORSED]
Fluorine is in the perfect place to fit that trend. It's in the top corner, so it makes sense that it would be the most electronegative.
- Wed Oct 25, 2017 12:19 pm
- Forum: Trends in The Periodic Table
- Topic: Across a period vs. Down a group
- Replies: 3
- Views: 494
Re: Across a period vs. Down a group
This might be something that can only be known from experimental values.
- Wed Oct 25, 2017 12:18 pm
- Forum: *Shrodinger Equation
- Topic: Electron Spin
- Replies: 6
- Views: 1102
Re: Electron Spin
A question that I have that is related to this topic is, can an electron change spin? Or will it always have the same spin no matter what?
- Wed Oct 18, 2017 8:53 pm
- Forum: Properties of Light
- Topic: the quantum world [ENDORSED]
- Replies: 3
- Views: 494
Re: the quantum world [ENDORSED]
I've been wondering about this too. It seems that we have to assume that something is both a particle and a wave until we know which one it is? But perhaps this is wrong. An explanation would be wonderful.
- Wed Oct 18, 2017 8:50 pm
- Forum: Ideal Gases
- Topic: Reading the textbook
- Replies: 262
- Views: 143908
Re: Reading the textbook
I find reading the textbook to be invaluable.
- Sat Oct 14, 2017 2:16 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Balmer/Lyman Series [ENDORSED]
- Replies: 7
- Views: 911
Re: Balmer/Lyman Series [ENDORSED]
I don't understand why the balmer series is specific to the visible light portion of the spectrum and the lyman series is specific to the UV portion. Maybe this is a stupid question? Could someone please explain.
- Sun Oct 08, 2017 12:41 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Saying Thank You to Dr. Lavelle
- Replies: 490
- Views: 503813
Re: Saying Thank You to Dr. Lavelle
Hi Dr. Lavelle,
I just wanted to say thank you for all of the great resources you've provided for us so far. You're a fantastic instructor!
I just wanted to say thank you for all of the great resources you've provided for us so far. You're a fantastic instructor!