## Search found 90 matches

Sat Mar 14, 2020 7:03 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: ENDGAME Q.10
Replies: 3
Views: 82

### ENDGAME Q.10

I do not unerstand why the cell potential for 10 is 0.43 volts when the oxidation reaction of silver is reduced. I thought when we reversed an oxidation reaction we changed he sign of its cell potential. Therefore, I thought the answer was (1.23V)-(-0.80V)= 2.03V
Sat Mar 14, 2020 6:22 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Endgame 2D
Replies: 3
Views: 77

### Re: Endgame 2D

Maybe double check the numbers you're using again? when I do 0.15*-2*96485/(8.314*298) I get the right answer How? I am doing the same calculation and I keep getting lnQ= -11.6. And for the concentration of Fe 2+ I get 9.2 x 10^-6. I've gone through the problem several times and I keep getting this...
Sat Mar 14, 2020 5:16 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Catalyst's effect on overall reaction
Replies: 7
Views: 120

### Re: Catalyst's effect on overall reaction

Hi all, In book problem 7.17, the textbook gives us the illustration of a reaction (A->D) and asks whether using a catalyst to accelerate the third step only would change the overall reaction rate. According to the solutions manual, it will not. I understand that the first step is the rate-determin...
Sat Mar 14, 2020 5:11 pm
Forum: Administrative Questions and Class Announcements
Topic: Where to find the final exam
Replies: 5
Views: 96

### Re: Where to find the final exam

Yes, the exam starts at 11:15am and ends at 2:45pm. Our final is 3 hours and 30 minutes. Thanks to Lavelle, the exam will be through CCLE, so no need to install apps or print anything
Fri Mar 13, 2020 7:10 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Pressure, Volume
Replies: 5
Views: 174

### Re: Pressure, Volume

well we know the ideal gas law inversely relates pressure with volume, pv=nRT, meaning as one increases the other decreases.
Fri Mar 13, 2020 7:05 pm
Forum: Balancing Redox Reactions
Topic: Oxidation number
Replies: 12
Views: 299

### Re: Oxidation number

How does oxidation number of an element relate to how many electrons it will lose or gain? I am confused on how to calculate when in acidic or basic solutions it changes the net charges. When balancing half reactions of a redox reaction, an elements change in oxidation number will tell you whether ...
Fri Mar 13, 2020 7:01 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Elementary Steps
Replies: 4
Views: 49

### Re: Elementary Steps

I think about individual particles travelling in a jar. The chances of 4 particles simultanesouly colliding with each other is far less likely than if 2 particles were to collide with each other.
Fri Mar 13, 2020 6:57 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Equilibrium Constant
Replies: 2
Views: 23

### Re: Equilibrium Constant

A catalyst does not affect the value of the equilibrium constant or the position of equilibrium. This is because adding a catalyst to a chemical reaction speeds both the forward and reverse reaction by the same rate.
Fri Mar 13, 2020 6:55 pm
Forum: Student Social/Study Group
Topic: final?
Replies: 7
Views: 270

### Re: final?

I'm pretty sure it's going to be taken by everyone at the same time. Lavelle sent an email about a simulated exam taken today.
Fri Mar 13, 2020 6:53 pm
Forum: Administrative Questions and Class Announcements
Topic: "Open Book" Final?
Replies: 30
Views: 925

### Re: "Open Book" Final?

I believe you are able to use any resources from lecture notes/discussions, and the textbook.
Fri Mar 13, 2020 6:48 pm
Forum: Zero Order Reactions
Topic: Calculus
Replies: 10
Views: 165

### Re: Calculus

You'll need especially when determing equilibrium constants. Whether it be understanding logs and antilogs, or determining the value of x from an ice table.
Fri Mar 13, 2020 6:45 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Nernst Equation
Replies: 1
Views: 30

### Re: Nernst Equation

This is correct, at equilibrium delta G equals zero and so does the cell potential.
Fri Mar 13, 2020 6:43 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: relationship to cell potential
Replies: 2
Views: 105

### Re: relationship to cell potential

The relationship between cell potential and gibbs free energy can be shown through the expression, deltaG = -nFEcell. You can also determine E cell by dividing deltaG/-nF.
Fri Mar 13, 2020 2:03 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Endgame review packet, question 2b
Replies: 2
Views: 52

### Re: Endgame review packet, question 2b

Thank you! What I did was I reversed the half-reaction for Fe and changed the sign of its cell potential. So I did (1.61V) - (+0.44V) to get 1.17v for the cell potential.
Fri Mar 13, 2020 1:40 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: salt bridge
Replies: 11
Views: 99

### Re: salt bridge

A sat bridge is usually comprised by a strong electrolyte which is further made up of ions. This salt bridge allows for the neutralization and flow of electrons between a cathode and anode solution. Without a proper salt bridge, the cathode solution will become negatively charged while the anode sol...
Fri Mar 13, 2020 1:32 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Endgame review packet, question 2b
Replies: 2
Views: 52

### Endgame review packet, question 2b

For question 2b, I got E cell = 1.17V. delta G = -226 kJ/mol. and for K I got 91.1. I just want to make sure these answers correlate with what my peers got.
Fri Mar 13, 2020 1:15 pm
Forum: Administrative Questions and Class Announcements
Topic: ENDGAME Review Session
Replies: 71
Views: 2979

### Re: ENDGAME Review Session

Thank you for everything and congratulations! Is there a specific time when we should expect the solutions?
Thu Mar 12, 2020 10:29 pm
Forum: Calculating Work of Expansion
Topic: Positive or negative work
Replies: 15
Views: 323

### Re: Positive or negative work

When work is done on the system, it is positive. When work is done by the system onto surroundings, it is negative. If the system exerts force on its surroundings, the system itself loses energy, explaining the negative value.
Thu Mar 12, 2020 10:27 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: dilutions and Ecell
Replies: 8
Views: 171

### Re: dilutions and Ecell

Diluting the cathode solution decreases the value of the cell potential, while diluting the anode solution increases the value of the cell potential. This is because of the differences between the anode and cathode when finding Ecell=Ecathode-Eanode.
Thu Mar 12, 2020 10:24 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Approximating X
Replies: 13
Views: 224

### Re: Approximating X

I specifically remember Lavelle mentioning in one of his lectures that if the value for K is less than (10^-3), then it is okay to approximate for x. Usually, just consider your initial moles of reactant and that the x value should leave no significant difference after subtracted from the moles of r...
Thu Mar 12, 2020 10:20 pm
Forum: Ideal Gases
Topic: When to use equation
Replies: 9
Views: 216

### Re: When to use equation

Probably not, usually you need to use an ice table to find moles or concentration of products given the moles or concentration of reactants. You can also sometimes just multiply it according to the ratio of their coefficients.
Thu Mar 12, 2020 10:14 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: E potential
Replies: 8
Views: 123

### Re: E potential

Yes, you want your cell potential to be positive. Therefore, the largest value will be the cathode. Keep in mind the formula, Ecell = E cathode - E anode.
Thu Mar 12, 2020 10:13 pm
Forum: Balancing Redox Reactions
Topic: Determing balanced rxns for a basic solution
Replies: 5
Views: 143

### Determing balanced rxns for a basic solution

I have a lot of trouble balancing the reactions in a basic solution all throughout. I remember my TA showing us a method of adding hydrogen protons the same way as if it were an acidic solution, but in the end, swapping out the protons for hydroxide ions and balancing the reaction from there. Does t...
Thu Mar 12, 2020 10:09 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: n in NFE
Replies: 19
Views: 280

### Re: n in NFE

n is how many moles of electrons are transferred. First you need to determine the half rxns, then balance the oxidation and reducing reactions so that the electrons cancel out (and don't appear in overall rxn). Finally, once both half rxns are balanced, the coeffecient of both electrons is your valu...
Thu Mar 12, 2020 6:59 pm
Forum: General Science Questions
Topic: Study guide
Replies: 2
Views: 109

### Re: Study guide

I'm not sure if he got it from a specific place in our course material. I don't recognize it from the textbook.
Thu Mar 12, 2020 6:57 pm
Forum: Ideal Gases
Topic: reversing reactions
Replies: 80
Views: 387

### Re: reversing reactions

K is going to become inverse, so 1/K.
Mon Mar 09, 2020 6:31 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Textbook question 5.35 Part B
Replies: 2
Views: 88

### Re: Textbook question 5.35 Part B

Thank you, I got the answer 1.54 but the textbook says 1.54 x 10^-2. I'm pretty sure it's a flaw in the solutions
Mon Mar 09, 2020 6:23 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: predicting effects
Replies: 9
Views: 162

### Re: predicting effects

You wrote the question for ii wrong. The question asks what will happen to the amount of NO2 if SO2 is removed by condensation (both these compounds are products of the rxn). Removing SO2 requires the rxn to move forward (favoring and producing further product) to return to equilibrium.
Mon Mar 09, 2020 12:12 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Textbook question 5.35 Part B
Replies: 2
Views: 88

### Textbook question 5.35 Part B

For problem 5.35 in the textbook, how do we calculate the equilibrium constant from the given plot? I got the balanced rxn [2A -> B + 2C] If somebody could help for the equilibrium constant in part B I would really appreciate it
Sun Mar 08, 2020 11:41 pm
Forum: General Rate Laws
Topic: First vs Second vs Zero Order
Replies: 7
Views: 94

### Re: First vs Second vs Zero Order

Each order rxn will use a different formula for the determination of its rate. Of course, they will also use different formulas to determine its half life
Sun Mar 08, 2020 11:39 pm
Forum: Administrative Questions and Class Announcements
Topic: 100 or 50 posts?
Replies: 8
Views: 177

### Re: 100 or 50 posts?

Yes, but it is important that you have AT LEAST 50 for last quarter and 50 for this quarter since your TA will be checking the dates posted. So don't try to pass with only completing 40 this quarter because you did an extra of 60 last quarter.
Sun Mar 08, 2020 11:36 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Favoring reactions
Replies: 7
Views: 159

### Re: Favoring reactions

Correct, if the anode value is larger than the cathode, the reactants/ reverse reaction will be favored. You should also know that this means a negative cell potential, and a positive delta G
Sat Feb 22, 2020 8:29 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Determining if a cell reaction is spontaneuous
Replies: 5
Views: 65

### Determining if a cell reaction is spontaneuous

For example 6L.2 and 6L.2A in the 7th edition textbook, we are asked to write a cell reaction from an electrochemical cell. After writing the reaction, we are asked to determine whether or not the reaction is spontaneous dependent upon a positive cell potential. I don't understand how to answer this...
Sat Feb 22, 2020 7:50 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: n in -nFE
Replies: 12
Views: 156

### Re: n in -nFE

You need the moles of electrons transferred in a cell in order to cancel out the moles in Faraday's constant (mol x C/mol = C). To find the moles of electrons transferred, you write out both the oxidation and reduction half reactions, balance the reactions so the electrons cancel on both sides, and ...
Fri Feb 21, 2020 1:07 am
Forum: Balancing Redox Reactions
Topic: Homework 6K.3
Replies: 3
Views: 66

### Re: Homework 6K.3

Cl2 is both the oxidizing and reducing agent in this reaction.
Fri Feb 21, 2020 12:18 am
Forum: Balancing Redox Reactions
Topic: Homework problem 6K.1
Replies: 5
Views: 95

### Re: Homework problem 6K.1

Start by identifying the oxidized and reduced species. The oxidation number for Cr changes from +6 to +3, indicating reduction (gain of 3 electrons). The oxidation number for C changes from -2 to -1, indicating oxidation (loss of 1 electron). You now have the skeleton for your half-reactions: (Cr2O...
Fri Feb 21, 2020 12:14 am
Forum: Balancing Redox Reactions
Topic: HW problem 6k.1
Replies: 3
Views: 37

### HW problem 6k.1

Part D of this question asks us to "combine the half-reactions to produce a balanced redox equation". From the oxidation reaction, I got 2 electrons on the product side and from the reduction half-reaction, I got 6 electrons on the reactant side. The correct answer for part d multiplies th...
Thu Feb 20, 2020 6:26 pm
Forum: Administrative Questions and Class Announcements
Topic: Step-up sessions
Replies: 1
Views: 30

### Step-up sessions

Hey can someone link or direct me to the step-up sessions. Couldn't find them on the website, thanks
Thu Feb 20, 2020 6:17 pm
Forum: Ideal Gases
Topic: When to use equation
Replies: 9
Views: 216

### Re: When to use equation

I do not think so, if its a single constant value for volume you would be able to find moles. However, I do not see how you could find initial and final concentrations of a reaction only from that information.
Mon Feb 10, 2020 12:42 pm
Forum: Ideal Gases
Topic: Compressing a gas
Replies: 5
Views: 86

### Re: Compressing a gas

Compressing a gas means increasing the concentration of each gas. The reaction would favor the side with less moles of gas because it reduces the number of particles in the gas. Since volume and pressure are inversely related, when compressing a gas you are decreasing the volume and this is why the ...
Thu Jan 30, 2020 10:53 pm
Forum: Calculating Work of Expansion
Topic: Textbook Question 4A.1A
Replies: 1
Views: 49

### Textbook Question 4A.1A

The Question states "Water expands when it freezes. How much work does 100. g of water do when it freezes at 0degreeC and pushes back the metal wall of a pipe that exerts an opposing pressure of 1070 atm? The densities of water and ice at 0degreeC are 1.00 g/cm^3 and 0.92 g/cm^3, respectively.&...
Sat Dec 07, 2019 11:46 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: when to use what equation
Replies: 5
Views: 69

### Re: when to use what equation

[H+]= 10^-pH [OH-}= 10^-pOH pH=-log[H+] pH= 14-(-log[OH-])
Sat Dec 07, 2019 11:39 pm
Forum: Bronsted Acids & Bases
Topic: Main Difference
Replies: 8
Views: 200

### Re: Main Difference

Lewis acids/bases accept/donate electron pair. Bronsted acids/bases accept/donate hydrogen protons
Sat Dec 07, 2019 11:36 pm
Forum: Conjugate Acids & Bases
Topic: how to figure out?
Replies: 12
Views: 289

### Re: how to figure out?

You find a conjugate base/acid by donating/accepting the acidic hydrogen proton in the reaction.
Sat Dec 07, 2019 11:34 pm
Forum: Hybridization
Topic: Pi bond
Replies: 10
Views: 263

### Re: Pi bond

Yes, and also when describing the hybridization of pi bonds they will be the same. Ex. in a triple bond, the descriptions of both pi bonds would be the same and would exist in the p orbital
Sat Dec 07, 2019 11:33 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Linear VSEPR model
Replies: 21
Views: 543

### Re: Linear VSEPR model

it will create a bent molecular shape
Sat Dec 07, 2019 11:33 pm
Forum: Hybridization
Topic: Lone pairs in hybridization
Replies: 4
Views: 141

### Re: Lone pairs in hybridization

Yes, you count all regions of e- density when considering the orbitals of hybridization. Say an atom has 2 bonds and 1 lone pair, then the hybridization would be sp2.
Sat Dec 07, 2019 11:31 pm
Forum: Dipole Moments
Topic: Melting and Boiling Points
Replies: 9
Views: 302

### Re: Melting and Boiling Points

Ionic bonds will always create the highest boiling points, hydrogen bonds are just exceptionally strong dipole-dipole interactions. Follow the general rule ionic>hydrogen bonding>dipole dipole>London dispersion
Sat Dec 07, 2019 11:29 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Electron Configuration
Replies: 10
Views: 184

### Re: Electron Configuration

Just remember to write them in numerical order, this is because of the energy levels.
Sat Dec 07, 2019 11:23 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Magnetic Quantum numbers
Replies: 4
Views: 181

### Re: Magnetic Quantum numbers

Ml can be within the range of -l to l. You look at the placement of the last electron to determine the value of Ml. For example, if an electron is in the p orbital in the 2nd slot, its Ml would be 0 because it is in the middle of the range from -1 to 1.
Sat Dec 07, 2019 11:19 pm
Forum: Properties of Electrons
Topic: Mass of an electron
Replies: 9
Views: 392

### Re: Mass of an electron

No, it will be given on the reference sheet so you don't have to concern yourself with memorizing the number.
Sat Dec 07, 2019 11:19 pm
Forum: Trends in The Periodic Table
Replies: 11
Views: 323

### Re: Atomic Radii

For strength in bonds will be most likely for the final. To the left and down are the trends for increasing atomic radii. The larger the distance between the centers of the atoms, the weaker the bonds. The weaker the bond, the stronger the acid and base (because a strong acid and base will completel...
Sat Dec 07, 2019 11:17 pm
Forum: Quantum Numbers and The H-Atom
Topic: Calculating quantum numbers
Replies: 4
Views: 175

### Re: Calculating quantum numbers

Focus on the last electron when calculating quantum numbers. N and L can be calculated by simply looking at the primary quantum number and the angular orbital number. Ml and Ms will tell you the spin and specific orbital of that electron.
Sat Dec 07, 2019 11:15 pm
Forum: Photoelectric Effect
Topic: Midterm Question 2B
Replies: 2
Views: 144

### Re: Midterm Question 2B

The graph looks the way it does because once the threshold frequency is met, electrons are instantly emitted. The same number of electrons are emitted assuming the intensity is constant. An increasing frequency (after the threshold frequency) has no effect on the number of photons emitted, they will...
Sat Dec 07, 2019 11:13 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: ph concept
Replies: 5
Views: 110

### Re: ph concept

please quote my question so i get a notification, thanks in advance! i know there is something wrong with my thought process, but i cannot figure it out. my thought process is that if a base is weaker, less oh- will be dissociated out. taking the -log of that smaller number will result in a smaller...
Wed Dec 04, 2019 6:34 pm
Forum: Photoelectric Effect
Topic: Intensity in Photoelectric Effect
Replies: 6
Views: 232

### Re: Intensity in Photoelectric Effect

Intensity means the number a photons, a higher intensity means a higher number of photons. Unless the threshold frequency is met, electrons will not be emitted regardless of the lights intensity (number of photons). If the threshold frequency is met, increasing intensity will then increase the numbe...
Wed Dec 04, 2019 6:29 pm
Forum: Photoelectric Effect
Topic: Midterm Question
Replies: 4
Views: 175

### Re: Midterm Question

Thank you all for the replies -- I get why it goes across now, but I still don't understand why it goes straight up? When the threshold frequency is met, the electrons are emitted instantly. If it were to be linear it would assume that electrons are emitted as frequency increases which is not the c...
Wed Dec 04, 2019 6:27 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bent vs linear
Replies: 56
Views: 1305

### Re: Bent vs linear

Liner shapes will have 2 bonding atoms and 1 or 2 lone pairs on the central atoms. Linear shapes are also 2 bonding atoms but will have either zero or 3 lone pairs on the central atom. AX2E, AX2E2 = bent. AX2, AX2E3= linear. Also, bent shapes are more likely to be polar than linear shapes
Wed Dec 04, 2019 6:14 pm
Forum: Einstein Equation
Topic: When do we use the Einstein Equation?
Replies: 14
Views: 442

### Re: When do we use the Einstein Equation?

E=hv will give you the energy of a photon. You should use it when finding frequency given energy or to find energy when given frequency.
Wed Dec 04, 2019 6:12 pm
Forum: Student Social/Study Group
Topic: Finals Preparation
Replies: 7
Views: 182

### Re: Finals Preperation

Just make sure you eat an apple, glucose molecules will store in your body and fuel your brain ability!
Wed Dec 04, 2019 6:09 pm
Forum: General Science Questions
Topic: Review in General
Replies: 4
Views: 128

### Re: Review in General

You should attend office hours and review sessions. They really make all the difference!
Fri Nov 15, 2019 10:28 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bent molecular shapes (AX2E2)
Replies: 1
Views: 76

### Bent molecular shapes (AX2E2)

Why is it that molecules with AX2E2 VSEPR formula are bent with the electrons beside each other? For example, ClO2 is bent, but I'm wondering why the Lone pairs on Cl aren't opposite of each other. Instead, they are closer together and push the Oxygen atoms closer together. I don't understand why lo...
Tue Nov 12, 2019 9:07 pm
Forum: Bond Lengths & Energies
Topic: Dissociation Energy
Replies: 9
Views: 103

### Re: Dissociation Energy

Dissociation energy is always positive because energy is always absorbed for dissociation. To break a bond requires an additional absorption of energy
Tue Nov 12, 2019 9:05 pm
Forum: Trends in The Periodic Table
Topic: Electronegativity
Replies: 9
Views: 269

### Re: Electronegativity

Yes, ionization and electronegativity of atoms follow the same periodic trends. Remember however that there are exceptions to ionization trends.
Tue Nov 12, 2019 9:03 pm
Forum: Trends in The Periodic Table
Topic: Ionization energy
Replies: 6
Views: 184

### Re: Ionization energy

From periodic trends, it can be incorrectly assumed that Oxygen has a higher ionization energy than Nitrogen. However, Oxygen wants a full shell so is more willing to give up its electrons (requiring less energy to its electrons and therefore giving Oxygen a lower ionization energy than Nitrogen).
Tue Nov 12, 2019 9:00 pm
Forum: Einstein Equation
Topic: When do we use the Einstein Equation?
Replies: 14
Views: 442

### Re: When do we use the Einstein Equation?

When relating energy of a photon to frequency, we use Einsteins equation. And if kinetic energy=0, we can also use it for the energy required to remove an electron. So, E = hv is used for relating the energy of a photon to its frequency, (remember that energy of a photon and its frequency are direct...
Tue Nov 12, 2019 8:56 pm
Forum: Properties of Electrons
Topic: Work Function
Replies: 4
Views: 174

### Re: Work Function

Clara Cho wrote:If I'm solving for the energy of a photon, would I use J/mol or J/electron?

J/mol of photon
Tue Nov 12, 2019 8:55 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Solving with velocity
Replies: 3
Views: 138

### Re: Solving with velocity

For the sake of Heisendbergs equation, the change in velocity is important. A singular value for velocity is more relevant to debroglies
Tue Nov 12, 2019 8:46 pm
Forum: Photoelectric Effect
Topic: Threshold
Replies: 3
Views: 144

### Re: Threshold

No, the threshold is not a constant value. The question should specify your threshold
Tue Nov 12, 2019 8:43 pm
Forum: DeBroglie Equation
Topic: When to Use
Replies: 8
Views: 202

### Re: When to Use

If you are relating wavelength to either mass or velocity, then you know you should use DeBroglies equation. Please keeep in mind that momentum uses Kg for mass and m/s for velocity.
Tue Nov 12, 2019 8:40 pm
Forum: Quantum Numbers and The H-Atom
Topic: Quantum Numbers
Replies: 1
Views: 106

### Quantum Numbers

On the midterm we were asked to provide "all" quantum numbers. To my understanding, can someone just sum up the quantum numbers we were supposed to use (Not the actual qualitative answer).
Wed Nov 06, 2019 5:21 pm
Forum: Administrative Questions and Class Announcements
Topic: Midterm
Replies: 1
Views: 52

### Midterm

Should we be writing our midterm with pen or pencil?
Thu Oct 31, 2019 11:30 pm
Forum: *Black Body Radiation
Topic: Will this concept be tested
Replies: 8
Views: 790

### Re: Will this concept be tested

No testing on this information, it's pretty complex too so I wouldn't spend too much time trying to deeply understand it if you won't be tested on it. Basic concept of it should be enough for the sake of your general chemistry understanding
Fri Oct 25, 2019 1:09 am
Forum: Einstein Equation
Topic: 1B.9
Replies: 5
Views: 270

### Re: 1B.9

To find photons, you first multiply Watts by 2 seconds and get 64 J/2sec as the Total Energy. Then, you find the energy per photon by using the formula E=(hc)/lambda, (energy per photon should be 4.717 x 10^-19). Divide energy per photon by total energy, and you get the number of photons [1.35 x 10^...
Thu Oct 24, 2019 7:07 pm
Forum: Photoelectric Effect
Topic: Photoelectric effect [ENDORSED]
Replies: 6
Views: 620

### Re: Photoelectric effect[ENDORSED]

You convert from nm to m by mnultiplying by 10^-9. However, I am much more concerned as to how you got your value for the energy of a photon. Your kinetic energy is specified at a value of zero. You should've gotten the work function equal to the energy of the photon (since there's no excess energy)...
Sun Oct 20, 2019 11:06 pm
Forum: Properties of Electrons
Topic: Spin
Replies: 5
Views: 112

### Re: Spin

Adding on, once the orbitals in a subshell are filled, the electrons will then start spinning in pairs. It would be done in a manner minimizing energy and it'll probably make more sense when we discuss valence electrons role in bonding.
Sun Oct 20, 2019 10:58 pm
Forum: Properties of Light
Topic: Homework 4
Replies: 4
Views: 87

### Re: Homework 4

Most definitely, hw problems were specified to quantum world questions last week and no update has been sent out regarding hw questions. So it's safe for us to assume that the same applies for this week.
Sun Oct 20, 2019 10:57 pm
Forum: Properties of Light
Topic: Light as a wave
Replies: 4
Views: 92

### Re: Light as a wave

The intensity of the light does not depend on the location where light hits. Increasing the intensity of light is simply increasing the number of photons.
Sun Oct 20, 2019 10:54 pm
Forum: *Shrodinger Equation
Topic: Schrodinger for exam
Replies: 20
Views: 445

### Re: Schrodinger for exam

Yes, at the very least understand its purpose/application.
Fri Oct 18, 2019 12:57 am
Forum: Photoelectric Effect
Topic: HW 1B.5
Replies: 8
Views: 161

### Re: HW 1B.5

I converted KeV directly to Joules so I also don't understand the ned to multiply KeV by 10^3. However, I am also very confused as to how these units cancel and my final answer was lambda=8.831pm. I multiplied plancks constant by c and got 1.9878x10^-25. I then divided the product by energy in joule...
Sun Oct 13, 2019 5:28 pm
Forum: Properties of Electrons
Topic: Diffraction
Replies: 6
Views: 69

### Re: Diffraction

Constructive diffraction results from waves in phase and destructive results from waves out of phase. Diffraction patterns result from interacting waves (the 2 types of interference previously mentioned), meaning that e- must have wavelike properties.
Sun Oct 13, 2019 5:24 pm
Forum: Balancing Chemical Reactions
Topic: Combustion
Replies: 17
Views: 627

### Re: Combustion

A complete combustion will always be in the following format. (Fuel) + O2 -> CO2 + H2O.
Sun Oct 13, 2019 5:21 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Showing work in detail
Replies: 7
Views: 333

### Re: Showing work in detail

You should be fine not including the units for calculations (simply because it consumes too much of your limited time in tests). However, you should include units for every result of calculation so that you and your T.A. can clearly identify where your numbers are coming from
Sun Oct 13, 2019 5:19 pm
Forum: DeBroglie Equation
Topic: Diffraction patterns
Replies: 4
Views: 70

### Diffraction patterns

I undertstand that diffraction patterns result from constructive and destructive interference but what is the difference between the 2 and how do I identify them?
Sun Oct 13, 2019 5:11 pm
Forum: General Science Questions
Topic: Audio-Visual focus topics
Replies: 4
Views: 45

### Audio-Visual focus topics

Is there a set time when we should complete each topic or are we allowed to study them whenever we feel fit?
Fri Oct 04, 2019 2:50 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Wrong Textbook
Replies: 12
Views: 506

### Re: Wrong Textbook

I only have the 6th edition and the class website specifies a requirement of the 7th edition. However, comparing mine to the other textbooks the HW questions are exactly the same and there don't seem to be any major discrepancies. If you have the 6th edition you can assume you'll be fine in terms of...
Fri Oct 04, 2019 2:45 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: E15
Replies: 3
Views: 114

### Re: E15

I own the 6th edition and I didn't see chloride mentioned anywhere in the problem. However, this is how I answered. First, I subtracted the molar mass of (OH) from the molar mass of the metal hydroxide: (74.1) g/mol metal hydroxide - (32) g/mol (OH)= (42.1) g/mol metal Next, I added the molar mass o...
Fri Oct 04, 2019 2:36 pm
Forum: Limiting Reactant Calculations
Topic: Percent Yield
Replies: 6
Views: 92

### Re: Percent Yield

Usually a question will ask you for the yield in grams. In any case, both theoretical and actual yields must be in the same units then multiplied by 100 for the correct percent yield.
Fri Oct 04, 2019 2:29 pm
Forum: Empirical & Molecular Formulas
Topic: Difference between empirical and molecular formulas
Replies: 6
Views: 147

### Re: Difference between empirical and molecular formulas

An empirical formula shows the relevant number of atoms a molecule has *ratio between atoms*, while a molecular formula shows the actual number of atoms *existing atoms*. The molecular formula will always be a multiple of the empirical.
Fri Oct 04, 2019 2:24 pm
Forum: Einstein Equation
Topic: 1B.7 (sixth edition)
Replies: 1
Views: 75

### 1B.7 (sixth edition)

When given wavelength and moles of atoms, how do I find energy emitted by that atom? specific question asks to find energy emitted by 1.00 mol of sodium atoms emitting light at a wavelength of 589 nm, but i'd prefer a response with the procedure instead of the answer to the specific question.

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