## Search found 81 matches

Sat Mar 16, 2019 6:36 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Units in Nernst Equation
Replies: 1
Views: 178

### Units in Nernst Equation

When using Nerst equation, do we have to worry about the units of Farraday's constant being in Coulombs while R is in joules?
Sat Mar 16, 2019 11:17 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Changing E˚ values
Replies: 2
Views: 88

### Changing E˚ values

In problem 6L.3 c), there are two moles of Ce4+ + 1e- --> Ce3+ however the E˚ value does not change. Do E˚ values ever change with the number of moles increases?
Sat Mar 16, 2019 10:30 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: ∆H and q [ENDORSED]
Replies: 6
Views: 267

### Re: ∆H and q[ENDORSED]

004932366 wrote:At constant pressure with no nonexpansion work, delta H is equal to q.

So at constant pressure and constant volume?
Fri Mar 15, 2019 11:05 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Gibbs Free Energy
Replies: 2
Views: 261

### Gibbs Free Energy

When is the standard gibbs free energy of formation equal to zero?
Fri Mar 15, 2019 9:33 am
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Reactions with multiple reactants
Replies: 2
Views: 93

### Re: Reactions with multiple reactants

k' is generally used instead of k to symbolize the rate of the reverse reaction, as to your specific question, A is probably in the products of the reaction you are looking at, which is why you would have k'. However, you would need to see the reaction to know this for sure. Do you have the given r...
Fri Mar 15, 2019 9:30 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: ∆H and q [ENDORSED]
Replies: 6
Views: 267

### ∆H and q[ENDORSED]

Under what conditions does ∆H equal q?
Thu Mar 14, 2019 12:18 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Review Session-Thermo-files- Wednesday-Q11-clarification [ENDORSED]
Replies: 10
Views: 671

### Re: Review Session-Thermo-files- Wednesday-Q11-clarification[ENDORSED]

In problem 10, how do we know that ∆H = q?
Wed Mar 13, 2019 8:43 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Reactions with multiple reactants
Replies: 2
Views: 93

### Reactions with multiple reactants

I'm still a little confused on this concept on determining the rate. In lecture, we said if [A]0 >> [B]0 and [C]0 then rate = k'[A]^N. Why do we use k' instead of k?
Wed Mar 13, 2019 8:16 pm
Forum: Student Social/Study Group
Topic: class pictures
Replies: 15
Views: 1258

### Re: class pictures

I have a picture from afar of Michelle receiving her award!
Wed Mar 13, 2019 8:13 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Catalyst vs. Intermediate
Replies: 8
Views: 176

### Re: Catalyst vs. Intermediate

Yvonne Du wrote:A catalyst is involved in the starting of the reaction, while an intermediate joins in later. Both of them are not included in the rate law.

Today, my TA said that a catalyst can be included in the rate law. Can someone clarify?
Wed Mar 13, 2019 8:11 pm
Forum: Student Social/Study Group
Topic: Key Words
Replies: 2
Views: 325

### Key Words

What are some good keywords to search to find review sheets from the TAs and UAs?
Wed Mar 13, 2019 8:04 pm
Forum: Phase Changes & Related Calculations
Replies: 3
Views: 228

In the review session tonight, the TA used the word adiabatic to describe a reaction in which we knew q=0 because it was "adiabatic." Does adiabatic mean the same thing as isothermic?
Wed Mar 13, 2019 1:08 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Catalyst vs. Intermediate
Replies: 8
Views: 176

### Re: Catalyst vs. Intermediate

An intermediate is something formed in a reaction and then used up later. A catalyst is present at the beginning of the reaction.
Wed Mar 13, 2019 1:04 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Problem 4A.9) 7th edition of the textbook [ENDORSED]
Replies: 7
Views: 27080

### Re: Problem 4A.9) 7th edition of the textbook[ENDORSED]

Thank you!
Wed Mar 13, 2019 1:03 pm
Forum: General Rate Laws
Topic: Reaction Order
Replies: 5
Views: 132

### Re: Reaction Order

Thank you!
Sun Mar 10, 2019 5:01 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: Reaction Constant k
Replies: 2
Views: 86

### Reaction Constant k

What factors affect k? Does it change with temperature like equilibrium constants? Is k different for every reaction?
Sun Mar 10, 2019 4:54 pm
Forum: First Order Reactions
Topic: Graphs
Replies: 2
Views: 80

### Re: Graphs

I'm not sure the answer to this question exactly, but I think we should know the graphs for different order reaction. For a first order reaction, there is a linear plot of ln[A] vs. t For a second order reaction, there is a linear plot of 1/[A] vs. t For a zero order reaction, there is a linear plot...
Sun Mar 10, 2019 4:51 pm
Forum: General Rate Laws
Topic: Reaction Order
Replies: 5
Views: 132

### Reaction Order

How do we know if a reaction is first/second order? and What does it mean for a reaction to be first/second order?
Sun Mar 03, 2019 7:58 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Q and K with the Nernst Equation
Replies: 3
Views: 88

### Re: Q and K with the Nernst Equation

I think you would need to find both and then from there you can tell which direction the reaction is preceding based on Q's relationship to K.
Sun Mar 03, 2019 7:57 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Class on 2/27 and 3/1
Replies: 2
Views: 73

### Class on 2/27 and 3/1

I was absent from class on Wednesday and Thursday of last week because I was away at a swim meet. Can someone tell me what we covered in class?
Sun Mar 03, 2019 7:53 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Gibbs free energy and temperature
Replies: 3
Views: 142

### Re: Gibbs free energy and temperature

As the temperature increases and the change in enthalpy and the change in entropy stay constant, the change in gibbs free energy decreases and vice versa. This can be seen in the equation ∆G = ∆H - T∆S.
Sun Feb 24, 2019 2:37 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Test 2
Replies: 9
Views: 289

### Re: Test 2

So will we need all of enthalpy and entropy for test 2?
Sat Feb 23, 2019 12:16 pm
Forum: Van't Hoff Equation
Topic: Deriving Equations
Replies: 3
Views: 112

### Re: Deriving Equations

I agree, I don't think we will have to know how to derive the equations, but we will need to know how/when to use and apply them. Additionally, I think understanding the derivations helps make the material clearer and gives a deeper understand of why that equations works.
Sat Feb 23, 2019 12:14 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Salt bridge
Replies: 3
Views: 96

### Re: Salt bridge

The main role of a salt bridge is to maintain neutrality in the cathode and the anode so the flow of electrons is continuous.
Sat Feb 23, 2019 12:10 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: cell diagram order
Replies: 2
Views: 63

### Re: cell diagram order

To add to what Eunice Lee 1A said, I think that the Pt is written on whichever side (either anode, cathode, or both) do not have a solid substance (so both are aqueous solutions)
Sun Feb 17, 2019 1:02 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Gibbs Free Energy in relation to H and S
Replies: 3
Views: 93

### Re: Gibbs Free Energy in relation to H and S

I think it all comes back to this equation: ∆G = ∆H - T∆S
Sun Feb 17, 2019 12:58 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: At Equilibrium G
Replies: 6
Views: 152

### Re: At Equilibrium G

904936893 wrote:If K = 0, is the reaction at equilibrium?

I think so since the reaction is no longer releasing or requiring energy.
Sun Feb 17, 2019 12:54 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Spontaneous Reactions
Replies: 2
Views: 63

### Re: Spontaneous Reactions

Spontaneous means the reaction is happening on its own, meaning there is no extra energy input require. Exergonic reactions are spontaneous since they happened without the addition of energy.
Wed Feb 13, 2019 1:27 pm
Forum: Administrative Questions and Class Announcements
Topic: Lyndon's HOTDOG MIDTERM REVIEW SESSION!! FINALLY!
Replies: 49
Views: 3354

### Re: Lyndon's HOTDOG MIDTERM REVIEW SESSION!! FINALLY!

Can anyone explain 3b?
Wed Feb 06, 2019 8:58 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Heat Capacity vs. Specific Heat
Replies: 2
Views: 113

### Heat Capacity vs. Specific Heat

Why in finding the heat capacity of the calorimeter do we ignore n in the equation q = nC∆T? I think it has something to do with heat capacity vs. specific heat but I'm not sure.
Wed Feb 06, 2019 8:22 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Problem 4A.9) 7th edition of the textbook [ENDORSED]
Replies: 7
Views: 27080

### Re: Problem 4A.9) 7th edition of the textbook[ENDORSED]

In this problem, the solutions manual says that heat lost by metal = - heat gained by water. Why would the heat gained by water be negative?
Wed Feb 06, 2019 5:25 pm
Forum: Administrative Questions and Class Announcements
Topic: Dr. Lavelle's In-class Review Sessions
Replies: 2
Views: 86

### Re: Dr. Lavelle's In-class Review Sessions

I'm assuming the same ones since they are during the different lecture times, but I'm not sure.
Wed Feb 06, 2019 5:24 pm
Forum: Calculating Work of Expansion
Topic: Integral Expression for Work
Replies: 4
Views: 126

### Integral Expression for Work

Will we ever need to use the integral equation or do we just need to understand it and be able to apply the variations of it?
Wed Feb 06, 2019 5:19 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Kb and nR
Replies: 1
Views: 56

### Kb and nR

In class we said that ∆S = KB ln (v2/v1) and that ∆S = nR ln (v2/v1). In this case, Boltzmann's constant and R times the number of moles must be equal. However, the number of moles can change for different gases, so can someone explain why these equations are equal?
Wed Feb 06, 2019 5:15 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Degenerate states and volume
Replies: 1
Views: 31

### Degenerate states and volume

In class today, Professor Lavelle said that doubling the volume of an ideal gas also doubles w, the amount of degenerate states, because each gas molecule has 2x the positions availible to it. I'm still confused what the relationship between volume and degenerate states are. Why does doubling the vo...
Sun Feb 03, 2019 2:59 pm
Forum: Calculating Work of Expansion
Topic: internal vs. external pressure
Replies: 3
Views: 323

### internal vs. external pressure

Why is a system is at equilibrium is the internal pressure approximately equal to the external pressure?
Sun Feb 03, 2019 2:55 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Enthalpy
Replies: 3
Views: 95

### Enthalpy

Im still a little confused on the definition of enthalpy, specifically in relationship to heat. So how is enthalpy different than heat?
Sun Feb 03, 2019 2:46 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Specific Combustion Reaction
Replies: 2
Views: 76

### Re: Specific Combustion Reaction

I think because there is no carbon on the reactants side of the equation. So it would just be 2 H2 + O2 --> 2 H20
Sun Jan 27, 2019 6:04 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Hess's Method
Replies: 2
Views: 86

### Re: Hess's Method

Hess's method is where you look at multiple different reactions and their standard reaction enthalpies to determine the standard reaction enthalpy of you desired reaction. This is an example from class: We want the standard enthalpy for N2 + 2 O2 --> 2 NO2 N2 + O2 --> 2 NO ∆H = 180 kJ 2 NO + 02 --> ...
Sun Jan 27, 2019 5:49 pm
Forum: Administrative Questions and Class Announcements
Topic: Lecture Slides
Replies: 5
Views: 171

### Lecture Slides

Are the lecture slides posted anywhere online?
Sat Jan 26, 2019 5:13 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Enthalpy Units
Replies: 7
Views: 195

### Enthalpy Units

What are the units for enthalpy? Sometimes its written in kJ but other times its kJ mol-1. Is there a difference?
Sun Jan 20, 2019 4:08 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Bars vs. Molarity
Replies: 5
Views: 135

### Re: Bars vs. Molarity

I'm not sure there is a specific case when you need to use one or the other, I think it depends more on what the problems gives you.
Sun Jan 20, 2019 4:07 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Autoprotolysis
Replies: 3
Views: 71

### Re: Autoprotolysis

The autoprotolysis constant is Kw = [H3O+][OH-] = 1.0 x 10^-14 where the concentration of H3O+ and OH- are 1.0 x 10^-7
Sun Jan 20, 2019 4:05 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Calculating pH from weak base and its salt (ex. from class)
Replies: 2
Views: 78

### Calculating pH from weak base and its salt (ex. from class)

In class we were given a problem that said: What is the pH of a solution with 0.100 M HNO2 and 0.150 M KNO2? The equation we used was to describe this reaction was HNO2 + H2O --> H3O+ + NO2- I understand that K + is not included in the equation because it is on both sides, however, why wouldn't ther...
Sun Jan 13, 2019 12:28 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: "bar" meaning
Replies: 4
Views: 129

### Re: "bar" meaning

Yes, bar is a unit to measure pressure which is approximately equal to an atm, however its slightly larger.
Thu Jan 10, 2019 6:38 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Homework 5G.11 7th edition
Replies: 1
Views: 60

### Homework 5G.11 7th edition

For 5G.11a, the different components are in different states of matter, so I'm not sure how to calculate Q. Can someone explain how I would do this?
Wed Jan 09, 2019 7:09 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Temperature and Equilibrium
Replies: 3
Views: 113

### Re: Temperature and Equilibrium

In general how can you tell if determine if a reaction is exothermic or endothermic?
Sat Dec 08, 2018 10:33 pm
Forum: Identifying Acidic & Basic Salts
Topic: Homeword 6D11 7th edition
Replies: 2
Views: 202

### Homeword 6D11 7th edition

I'm confused why KF would form a solution with a pH greater than 7 but then KBr's solution is still neutral.
Sat Dec 08, 2018 10:31 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Question 6B3
Replies: 1
Views: 56

### Re: Question 6B3

The number inside the parentheses is the new molarity that they found using the eqautions: (MinitialVinitial)/Vfinal = Mfinal.
Sat Dec 08, 2018 10:09 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Homework 6C.17
Replies: 1
Views: 55

### Homework 6C.17

I don't understand how to calculate which is the stronger base. Can someone explain it?
Sat Dec 08, 2018 10:06 pm
Forum: Biological Examples
Topic: Myoglobin, Hemoglobin, and Heme Complex
Replies: 2
Views: 221

### Re: Myoglobin, Hemoglobin, and Heme Complex

Is iron always at the center of a heme complex?
Sat Dec 08, 2018 7:44 pm
Forum: Administrative Questions and Class Announcements
Topic: FINAL PRACTICE - Lyndon's Churro Review Session [ENDORSED]
Replies: 118
Views: 8656

### Re: FINAL PRACTICE - Lyndon's Churro Review Session[ENDORSED]

I think I understand the basis of how to do number 34, but I keep getting a pH of 2.10. Did anyone else make the error same/know what my error is?
Sat Dec 08, 2018 4:52 pm
Forum: Administrative Questions and Class Announcements
Topic: FINAL PRACTICE - Lyndon's Churro Review Session [ENDORSED]
Replies: 118
Views: 8656

### Re: FINAL PRACTICE - Lyndon's Churro Review Session[ENDORSED]

For question 18, I'm having trouble finding the 180˚ bond. Which bond would it be?
Thu Nov 29, 2018 10:48 pm
Forum: Bond Lengths & Energies
Topic: 7th edition 2D.19
Replies: 2
Views: 212

### Re: 7th edition 2D.19

Yes thank you! Sorry I was reading part of 2D.19 then I looked at 2D.20 to get the part about the nitrogens!
Thu Nov 29, 2018 9:06 pm
Forum: Bond Lengths & Energies
Topic: 7th edition 2D.19
Replies: 2
Views: 212

### 7th edition 2D.19

I'm very confused on this problem! I thought I just added the covalent radii of the nitrogen atoms but the solutions manual says something else. Can anyone help me understand how to solve a problem like this?
Wed Nov 28, 2018 1:13 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: TM charge
Replies: 4
Views: 133

### TM charge

In class today, we saw how the nickel in [Ni (NH3)4 Cl] Cl 2 H2O had a charge of positive 2. I understand that the charge of +2 comes from the -1 charge on both of the Chlorine atoms, but how does the chlorine outside of the coordination compound affect the charge of the TM? Are the compounds outsid...
Sun Nov 25, 2018 6:21 pm
Forum: Lewis Acids & Bases
Topic: How do we know something is a lewis acid or base?
Replies: 4
Views: 184

### Re: How do we know something is a lewis acid or base?

A lewis acid is the electron acceptor and the lewis base is the electron donor!
Sun Nov 25, 2018 6:19 pm
Forum: Hybridization
Topic: Double Bonds
Replies: 4
Views: 155

### Double Bonds

How do double bonds affect hybridization?
Sun Nov 25, 2018 4:40 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: electron arrangement and molecular geometry
Replies: 1
Views: 33

### Re: electron arrangement and molecular geometry

Electron arrangement is the arrangement of electrons around the central atoms. So for example if an atom has two bonded pairs and two lone pair electrons, the electron geometry is tetrahedral. The molecular geometry is arrangement of the atoms around the central atom. While this does take into accou...
Wed Nov 14, 2018 6:52 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Angular Shape
Replies: 4
Views: 120

### Re: Angular Shape

Angular shape is when there is a central atom with two bonded molecules and one lone pair.
Wed Nov 14, 2018 6:51 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Strengths
Replies: 5
Views: 157

### Re: Bond Strengths

Additionally, ionic bonds are intramolecular while hydrogen bonds are intermolecular. And intramolecular bonds are always stronger than hydrogen bonds.
Wed Nov 14, 2018 6:49 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Linear vs angular and trigonal planar vs trigonal pyramidal
Replies: 2
Views: 152

### Re: Linear vs angular and trigonal planar vs trigonal pyramidal

You need to look at whether the electrons clouds are bonded electrons or lone pair electrons. When determining a molecule's VSEPR structure you look at bonded molecules, but also need to take into account where the lone pair electrons, if there are any, are located. As for your question, below are t...
Wed Nov 07, 2018 8:11 pm
Forum: Lewis Structures
Replies: 2
Views: 136

I think radicals are more reactive because they have an unequal number of electrons to match the number of protons in addition to the one electron not in a pair. Additionally, halogens are diatomic elements which means that they are usually found in pairs to eliminate the one unpaired electron.
Wed Nov 07, 2018 8:07 pm
Forum: Bond Lengths & Energies
Topic: MIDTERM Bond Length Question
Replies: 15
Views: 415

### Re: MIDTERM Bond Length Question

I believe that the Lewis structure for NO2 has one single bond and one double bond. So, in nature, this double bond would be evenly distributed between the two, so I assumed the each bond would be approximately a "1.5" bond. Using this logic, I guessed that the bond length would be about 1...
Wed Nov 07, 2018 7:58 pm
Forum: Dipole Moments
Topic: Why can't SO2 form Hydrogen bonds?
Replies: 3
Views: 616

### Re: Why can't SO2 form Hydrogen bonds?

SO2 can't form hydrogen bonds because there is no hydrogen. The bonds are polar as the S is slightly positive and the O is slightly negative, so there is some intermolecular bonding happening there, but without hydrogen, they are not classified as hydrogen bonds.
Sun Nov 04, 2018 4:21 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge
Replies: 7
Views: 272

### Re: Formal Charge

Well in a lot of cases not all of the atoms can have a formal charge of zero. In Lewis structures, I think we want as many atoms to have a formal charge of 0 as possible, but its especially important that the central atom have a formal charge of 0. Additionally there are only a few atoms that can ha...
Sun Nov 04, 2018 4:13 pm
Forum: Electronegativity
Topic: Trend Exceptions
Replies: 5
Views: 217

### Trend Exceptions

In my discussion, we saw how Be has a larger ionization energy than B even though B is farther to the right than Be because B has 1 electron in the 2p-orbital while Be has a full 2s-orbital. The same was true for N having a larger ionization energy than O because of its half full 2p-orbital. How do ...
Sun Nov 04, 2018 3:48 pm
Forum: Sigma & Pi Bonds
Topic: sigma and pi bonds
Replies: 2
Views: 110

### Re: sigma and pi bonds

I don't think so either since they were not covered in the classes that he said the midterm would cover
Fri Oct 26, 2018 7:13 pm
Forum: Trends in The Periodic Table
Topic: Isoelectronic atoms sizes [ENDORSED]
Replies: 3
Views: 165

### Re: Isoelectronic atoms sizes[ENDORSED]

The Na+ atom would be smaller and the Ne atom would bigger because they have the same number of electrons. However, since Na+ has one more proton, it has a tighter hold on its 10 electrons which makes the atom smaller.
Wed Oct 24, 2018 7:04 pm
Forum: Quantum Numbers and The H-Atom
Topic: spin
Replies: 4
Views: 126

### Re: spin

Based on what we've seen in class, I'm assuming the first electron in an orbital spins upwards (+1/2) and the second electron spins downwards (-1/2). Is this right?
Mon Oct 22, 2018 10:05 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Homework 1E.13
Replies: 1
Views: 49

### Homework 1E.13

As I was going through this problem, I realized once I got to the fourth energy level, I was unsure when to add 4f. For example, Sb goes from 4d10 to 5s2, but then W goes 4f14, 5d4, 6s2. Could someone explain when you should include the f orbital?
Sun Oct 21, 2018 4:03 pm
Forum: Quantum Numbers and The H-Atom
Topic: Quantum number M [ENDORSED]
Replies: 7
Views: 274

### Re: Quantum number M[ENDORSED]

In the M number, does -1 always correspond to x? For example is wave function (2,1, -1) have to mean 2px? or could it be 2py?
Sun Oct 21, 2018 4:00 pm
Forum: Properties of Electrons
Topic: Electron Spin
Replies: 7
Views: 434

### Electron Spin

I'm a little confused about the idea of electron spin. Why do electrons spin and why is the quantum number associated with it +/- 1/2?
Sun Oct 21, 2018 3:58 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: s, p, d, f subshells in multi-electron atoms
Replies: 6
Views: 179

### Re: s, p, d, f subshells in multi-electron atoms

In high school, I remember learning that the 4s- shell was before the 3d- shell because of how much larger the 3d- one was. Is this right?
Thu Oct 11, 2018 10:54 am
Forum: Properties of Light
Topic: Why Short Wavelengths Can Eject e-
Replies: 6
Views: 169

### Re: Why Short Wavelengths Can Eject e-

Short wavelengths can eject the electron because as Johnathan said they have a higher energy. The energy equation is E = hv. H is planck's constant, so that value never changes. However, the v is in regards to frequency, and we know that wavelength and frequency are inversely proportional (c = λ * v...
Thu Oct 11, 2018 10:46 am
Forum: Properties of Light
Topic: Memorizing wavelengths and frequencies
Replies: 5
Views: 189

### Re: Memorizing wavelengths and frequencies

I would say that you don't need to memorize the all of different wavelengths, but I would know the order of the different wavelengths and have a general idea of the range of wavelengths for each type if light.
Mon Oct 08, 2018 8:51 pm
Forum: Limiting Reactant Calculations
Topic: Question on Post-Module #22
Replies: 2
Views: 74

### Re: Question on Post-Module #22

I got the same answer as you and was also unsure how to get the correct answer here. Something I was wondering about was the units of the reactants: one was 0.750 g of C6H9Cl3 which is grams and the other, 1.000 kg of AgNO3, is in kilograms. I thought there might be a typo and they both should have ...
Fri Oct 05, 2018 10:38 am
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: atoms vs molecules vs formula units?
Replies: 3
Views: 87

### Re: atoms vs molecules vs formula units?

I'm not sure if this is correct, but my understanding is this:

atom: 1 unit of one element. for example, H is 1 hydrogen atom.
molecule: a molecule is a 2 or more atoms bonded together.
formula unit: the empirical formula of a compound.
Wed Oct 03, 2018 5:24 pm
Forum: SI Units, Unit Conversions
Topic: Week 1 Homework Assignment [ENDORSED]
Replies: 16
Views: 563

### Re: Week 1 Homework Assignment[ENDORSED]

In response to @Kristen Kim 1I question about the online discussion, I asked my TA and she said that we ask a question/comment three times per week to earn the 3 points!
Mon Oct 01, 2018 8:00 pm
Forum: Empirical & Molecular Formulas
Topic: Solving For Empirical and Molecular Formulas
Replies: 4
Views: 169

### Re: Solving For Empirical and Molecular Formulas

In this case, I'm not sure its completely necessary to find the percent composition because the question you're referring did not ask for it. Using the percent composition is definitely one way to do the problem, but you could do it another way since you know the mass of both substances. Here is my ...
Mon Oct 01, 2018 7:44 pm
Forum: SI Units, Unit Conversions
Topic: Week 1 Homework Assignment [ENDORSED]
Replies: 16
Views: 563

### Re: Week 1 Homework Assignment[ENDORSED]

How are you all picking which problems to do? I was thinking of turning in about one from the various fundamentals sections, but I was wondering if anyone had any other suggestions on which problems to do/turn in!