Search found 51 matches
- Fri Mar 16, 2018 2:48 am
- Forum: General Rate Laws
- Topic: Units
- Replies: 11
- Views: 1408
Re: Units
Just make sure all of your units are consistent.
- Fri Mar 16, 2018 2:46 am
- Forum: First Order Reactions
- Topic: Help on 15.3
- Replies: 7
- Views: 1015
Re: Help on 15.3
The units of k are always mol * L/s
- Fri Mar 16, 2018 2:46 am
- Forum: First Order Reactions
- Topic: Help on 15.3
- Replies: 7
- Views: 1015
Re: Help on 15.3
The units of k are always mol * L/s
- Fri Mar 16, 2018 2:45 am
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Arrhenius equation and order of rxn
- Replies: 3
- Views: 475
Re: Arrhenius equation and order of rxn
It technically can be used for all orders because order does not play a part in the equation.
- Fri Mar 16, 2018 2:43 am
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: 15.49
- Replies: 2
- Views: 383
Re: 15.49
Intermediates are not included in the overall rate law.
- Sat Mar 10, 2018 12:40 am
- Forum: Zero Order Reactions
- Topic: Zero order
- Replies: 5
- Views: 1213
Re: Zero order
If a zero order is in the reaction, the rate law is k[A]^0 = k. Therefore it has is not based on the concentration, only the rate constant.
- Sat Mar 10, 2018 12:38 am
- Forum: Second Order Reactions
- Topic: 3rd order?
- Replies: 7
- Views: 1177
Re: 3rd order?
I agree
- Sat Mar 10, 2018 12:36 am
- Forum: First Order Reactions
- Topic: Reaction Order [ENDORSED]
- Replies: 6
- Views: 957
Re: Reaction Order [ENDORSED]
I think it's more of just the exponent of the [A]. For example k[A]^2 would be a second order reaction
- Sat Mar 10, 2018 12:35 am
- Forum: First Order Reactions
- Topic: Units of Reactions. [ENDORSED]
- Replies: 5
- Views: 961
Re: Units of Reactions. [ENDORSED]
Basically whatever the exponent of [A] is the order of reaction.
- Fri Mar 02, 2018 7:50 pm
- Forum: General Rate Laws
- Topic: Test 3
- Replies: 3
- Views: 478
Re: Test 3
Ya, around number 43.
- Fri Mar 02, 2018 7:49 pm
- Forum: Zero Order Reactions
- Topic: Order Reactions [ENDORSED]
- Replies: 4
- Views: 815
Re: Order Reactions [ENDORSED]
The order of reactions describes how the concentrations and the rate of the reaction are correlated/related.
- Fri Mar 02, 2018 7:46 pm
- Forum: Zero Order Reactions
- Topic: Negative Order Reactions
- Replies: 3
- Views: 1702
Re: Negative Order Reactions
Yes. I agree
- Thu Feb 22, 2018 9:38 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Finding n
- Replies: 15
- Views: 1804
Re: Finding n
n is just the amount of electrons transferred in the reaction. Usually you need to find the half reactions first.
- Thu Feb 22, 2018 9:37 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Gibbs Free Energy vs. Cell Potential
- Replies: 2
- Views: 655
Re: Gibbs Free Energy vs. Cell Potential
This also brings up the fact that a positive E which is a negative G means the process if favorable
- Thu Feb 22, 2018 9:35 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: E of a Redox [ENDORSED]
- Replies: 5
- Views: 960
Re: E of a Redox [ENDORSED]
The E value will always remain the same because it is an intensive property.
- Fri Feb 16, 2018 3:58 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Effect of solids and liquids on K
- Replies: 3
- Views: 425
Re: Effect of solids and liquids on K
Correct, only aqueous and not solids or liquids.
- Fri Feb 16, 2018 3:55 pm
- Forum: Balancing Redox Reactions
- Topic: Salt Bridges
- Replies: 14
- Views: 1263
Re: Salt Bridges
The salt bridge keeps the two solutions neutral so that the redox reaction can continue.
- Fri Feb 16, 2018 3:54 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Multiplying Cathode Equation
- Replies: 2
- Views: 388
Re: Multiplying Cathode Equation
I agree. E is an intensive property which makes it independent of the mass.
- Fri Feb 09, 2018 7:33 pm
- Forum: Calculating Work of Expansion
- Topic: Integral [ENDORSED]
- Replies: 4
- Views: 834
Re: Integral [ENDORSED]
No, integrals were just done to understand the derivation.
- Fri Feb 09, 2018 7:31 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Isolated
- Replies: 9
- Views: 1052
Re: Isolated
The heat is changing within the isolated system. Not changing from the surroundings.
- Fri Feb 09, 2018 7:29 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: DG = -nFE
- Replies: 3
- Views: 586
Re: DG = -nFE
I think you just have to balance the equations.
- Fri Feb 02, 2018 7:51 pm
- Forum: Van't Hoff Equation
- Topic: Van't Hoff Eq.
- Replies: 5
- Views: 1011
Re: Van't Hoff Eq.
Both delta S and delta H remain constant from what Lavelle told us in class today.
- Fri Feb 02, 2018 7:50 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Midterm
- Replies: 6
- Views: 710
Re: Midterm
Probably both chapter 8 and 9. Chapter 11 might be in there too
- Fri Feb 02, 2018 7:49 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Open systems
- Replies: 6
- Views: 718
Re: Open systems
I think that most of the equations will deal with closed systems.
- Thu Jan 25, 2018 5:17 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: The sign of q
- Replies: 5
- Views: 1149
Re: The sign of q
qsys + qsurr = 0 is a "perfect system" with no extra released/absorbed.
- Thu Jan 25, 2018 5:16 pm
- Forum: Phase Changes & Related Calculations
- Topic: Phase Changes Equations
- Replies: 4
- Views: 572
Re: Phase Changes Equations
Most questions give the overall heat change but you should know how to solve for it. Doing a lot of problems in the textbook will give you a clearer idea on whether you need to know how to solve for the overall heat change.
- Thu Jan 25, 2018 5:14 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Heat capacity vs Specific Heat capacity
- Replies: 5
- Views: 688
Re: Heat capacity vs Specific Heat capacity
For specific molar heat capacity you either need gas at constant volume: Cv or at constant pressure Cp.
- Thu Jan 18, 2018 10:15 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Specific Heat Capacity
- Replies: 5
- Views: 2020
Re: Specific Heat Capacity
It just works with the questions to assume the specific heat capacity is the same as the solvent.
- Thu Jan 18, 2018 10:12 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Hess's Law
- Replies: 5
- Views: 452
Re: Hess's Law
The only thing you really need to know, since the path taken does not matter, is final state - initial state.
- Thu Jan 18, 2018 10:11 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Reaction Enthalpy v. Enthalpy of Formation
- Replies: 4
- Views: 276
Re: Reaction Enthalpy v. Enthalpy of Formation
Usually the problem states whether it involves Reaction Enthalpy or Enthalpy of Formation. Sometimes both are needed if given the information.
- Fri Jan 12, 2018 5:55 pm
- Forum: Phase Changes & Related Calculations
- Topic: Methods of Enthalpy
- Replies: 8
- Views: 808
Methods of Enthalpy
Are we going to have to use more than one method of finding the enthalpy in any problem?
- Fri Jan 12, 2018 5:53 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Heat capacity
- Replies: 4
- Views: 343
Heat capacity
How is heat capacity a state function if it is an intensive property?
- Fri Jan 12, 2018 5:51 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Hess Law
- Replies: 4
- Views: 347
Hess Law
Can someone explain Hess’ law and how it pertains to the net reaction? I followed during class but was a bit confused about this.
- Sun Dec 03, 2017 11:00 pm
- Forum: Sigma & Pi Bonds
- Topic: When do Sigma and Pi bonds occur?
- Replies: 4
- Views: 696
Re: When do Sigma and Pi bonds occur?
Just to add on, sigma bonds also allow the molecules to rotate, whereas they are in a locked position with pi bonds.
- Sun Dec 03, 2017 10:58 pm
- Forum: Lewis Structures
- Topic: Central Atom? [ENDORSED]
- Replies: 7
- Views: 2728
Re: Central Atom? [ENDORSED]
Hydrogen only has one electron. Because of this it cannot satisfy the octet rule and won't be the central atom
- Fri Nov 24, 2017 11:59 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Shifted VS Lie
- Replies: 2
- Views: 1573
Re: Shifted VS Lie
I think they would rather have us say that the equilibrium sits/lies to the left or right. Using the word shift implies that there is a movement and change which is not true.
- Fri Nov 24, 2017 11:57 pm
- Forum: Ideal Gases
- Topic: Q and K [ENDORSED]
- Replies: 35
- Views: 2939
Re: Q and K [ENDORSED]
There are no difference between the formuals. However, Q refers to the reactants and products whereas K refers to the chemical equilibrium.
- Thu Nov 16, 2017 12:02 am
- Forum: Hybridization
- Topic: Notation
- Replies: 6
- Views: 749
Re: Notation
You only need to write it out if the question needs the full electron configuration.
- Thu Nov 16, 2017 12:00 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bent vs Angular
- Replies: 7
- Views: 761
Re: Bent vs Angular
Yes, bent and angular both mean that the atoms are not bonded to the central atom linearly.
- Thu Nov 09, 2017 2:21 pm
- Forum: Electronegativity
- Topic: Ionic vs Covalent Based on Electronegativity Difference for LiI
- Replies: 2
- Views: 534
Re: Ionic vs Covalent Based on Electronegativity Difference for LiI
If the difference is <2 then the bond should be covalent. If the difference is >2 then the bond is ionic.
- Thu Nov 09, 2017 2:15 pm
- Forum: Octet Exceptions
- Topic: Octet Exceptions
- Replies: 8
- Views: 955
Re: Octet Exceptions
It's true that the expanded octet applies to those with an energy level of n=3 and higher. I think the most common ones we are going to see will be Phosphorus and Sulfur.
- Mon Nov 06, 2017 5:18 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Midterm
- Replies: 8
- Views: 884
Re: Midterm
Nope! the exam covers material from chapters 1-3, which does not include the VSEPR model.
- Mon Nov 06, 2017 5:13 pm
- Forum: Electronegativity
- Topic: ELECTRON AFFINITY
- Replies: 7
- Views: 1516
Re: ELECTRON AFFINITY
Are there any exceptions to the electron affinity increasing across the period?
- Fri Oct 27, 2017 1:10 pm
- Forum: Resonance Structures
- Topic: Delocalized
- Replies: 2
- Views: 524
Re: Delocalized
So when an electron is involved in resonance structures, it is considered delocalized.
- Fri Oct 27, 2017 1:08 pm
- Forum: Ionic & Covalent Bonds
- Topic: Cations and Anions [ENDORSED]
- Replies: 12
- Views: 2047
Re: Cations and Anions [ENDORSED]
A cation is an atom that has lost an electron, therefore it is positive. An anion has gained an electron, making it positive. Atoms can lose or gain more than one electron.
- Fri Oct 20, 2017 11:33 pm
- Forum: Properties of Light
- Topic: Color of visible light
- Replies: 11
- Views: 1188
Re: Color of visible light
No the most we would need to know is 400 nm being violet light and 700 nm is red light. Everything in between would either be given or it would not be asked for.
- Fri Oct 20, 2017 11:31 pm
- Forum: Einstein Equation
- Topic: Use of symbols
- Replies: 6
- Views: 1116
Re: Use of symbols
You definitely should ask your TA because they are the ones grading, but I would say go with v because that is standard.
- Fri Oct 13, 2017 4:00 pm
- Forum: Properties of Light
- Topic: Speed of Light Constant
- Replies: 18
- Views: 1675
Re: Speed of Light Constant
Using 2.998 x 10^8 is definitely the more accurate number. However rounding it to 3 won't cause too much of an error bound, so I don't think you would get the question wrong. But 2.998 is definitely the safe option because it is more accurate.
- Fri Oct 13, 2017 3:51 pm
- Forum: Properties of Electrons
- Topic: Series
- Replies: 6
- Views: 822
Re: Series
Do we still use Balmer's series if the electron is going excited from n=1 to n=2. I know that we use it when the electron goes from n=3 to n=2. Or do we use Lyman's series even though the electron ends up in the visible light spectrum?
- Thu Oct 05, 2017 3:47 pm
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: E.15 [ENDORSED]
- Replies: 10
- Views: 1565
E.15 [ENDORSED]
The molar mass of the metal hydroxide M(OH)2 is 74.10 g.mol^-1. What is the molar mass of the sulfide of this metal?
I was confused on finding the molar mass of the sulfide. Is there another number I am supposed to know to use to solve this problem?
I was confused on finding the molar mass of the sulfide. Is there another number I am supposed to know to use to solve this problem?
- Tue Oct 03, 2017 11:29 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: G7 - Homework Problem
- Replies: 5
- Views: 773
Re: G7 - Homework Problem
First you find the mass of KNO3, which is the percentage (5.45%) x the total mass of the aqueous solution (510g). Then you need to find the mass of the water before the KNO3 is added to it which is the total mass of the aqueous solution (510g) subtracted by the mass of KNO3. So to prep the solution ...