Search found 51 matches

by Matthew Lee 3L
Thu Mar 15, 2018 12:24 am
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: 15.63
Replies: 3
Views: 289

Re: 15.63

I believe if you set it up like that it should be ln(k1/k2) = (Ea/R)(1/T2 - 1/T1)
by Matthew Lee 3L
Thu Mar 15, 2018 12:22 am
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: 15.61
Replies: 3
Views: 261

Re: 15.61

Thank you!
by Matthew Lee 3L
Thu Mar 15, 2018 12:05 am
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: 15.61
Replies: 3
Views: 261

15.61

In the solutions manual for this problem, when it is setting up the equation why do you multiply the 1/T in (1/T - 1/T') by T/T and the 1/T' by T'/T' to get
((T' - T)/(TT'))? Why can't you just leave it as (1/T - 1/T')?
by Matthew Lee 3L
Fri Mar 09, 2018 1:40 am
Forum: General Rate Laws
Topic: Rate Constant k
Replies: 6
Views: 435

Re: Rate Constant k

The rate constant's units are also dependent on the order of the reaction.
by Matthew Lee 3L
Fri Mar 09, 2018 1:35 am
Forum: First Order Reactions
Topic: pseudoreactions [ENDORSED]
Replies: 2
Views: 218

Re: pseudoreactions [ENDORSED]

I would like to know this as well.
by Matthew Lee 3L
Thu Mar 08, 2018 5:52 pm
Forum: General Rate Laws
Topic: 15.19
Replies: 2
Views: 226

15.19

For Problem 15.19 how would you know whether or not you should convert mmol to mol when solving for k? You get a different answer if you solve after converting to mol than if you don't convert to mol. Also, in problem 15.17, when solving for k, you don't convert mmol to mol. Why is this?
by Matthew Lee 3L
Tue Feb 27, 2018 12:02 am
Forum: Method of Initial Rates (To Determine n and k)
Topic: 15.19
Replies: 3
Views: 260

15.19

When finding the overall order of the reaction in part a of 15.19, why do we not need to calculate the order in regards to reactant C?
by Matthew Lee 3L
Mon Feb 26, 2018 11:36 pm
Forum: General Rate Laws
Topic: 15.9
Replies: 5
Views: 361

Re: 15.9

On the syllabus, it says to omit this question from the homework.
by Matthew Lee 3L
Mon Feb 26, 2018 11:26 pm
Forum: General Rate Laws
Topic: 15.3/Unique Rate
Replies: 2
Views: 197

Re: 15.3/Unique Rate

Yes, because you are using the reaction rate of the reactant, NO2, you divide by its stoichiometric coefficient, which in this case is 2.
by Matthew Lee 3L
Mon Feb 26, 2018 11:24 pm
Forum: General Rate Laws
Topic: Unique rate of reaction Hw 15.3
Replies: 4
Views: 651

Re: Unique rate of reaction Hw 15.3

I think the solutions manual divides by 2, because it uses the reaction rate for NO2 which has a stoichiometric coefficient of 2.
by Matthew Lee 3L
Fri Feb 23, 2018 3:25 am
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: 14.31
Replies: 6
Views: 392

Re: 14.31

If the E is positive, this means that deltaG is negative which means the reaction is favorable. When it is favorable, there will be a higher concentration of products, causing K to be greater than 1.
by Matthew Lee 3L
Fri Feb 23, 2018 3:22 am
Forum: Balancing Redox Reactions
Topic: Cell Diagram [ENDORSED]
Replies: 7
Views: 424

Re: Cell Diagram [ENDORSED]

If they are in different states, they will be separated by lines. If they are in the same state, they will be separated by commas.
by Matthew Lee 3L
Fri Feb 23, 2018 3:12 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 14.13(b)
Replies: 2
Views: 163

Re: 14.13(b)

The correct way to write it would be for each side, to have reactants, then products. This is why I2(s) is in the third position.
by Matthew Lee 3L
Fri Feb 16, 2018 12:30 pm
Forum: Balancing Redox Reactions
Topic: Balancing redox rxns [ENDORSED]
Replies: 7
Views: 447

Re: Balancing redox rxns [ENDORSED]

I don't think there is an exact set of steps to follow. You should just balance it however you feel comfortable.
by Matthew Lee 3L
Fri Feb 16, 2018 12:08 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: cell potential equations
Replies: 3
Views: 393

Re: cell potential equations

Maybe you made some calculation error along the way or plugged numbers in your calculator wrong. They should be the same.
by Matthew Lee 3L
Fri Feb 09, 2018 12:08 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: HW 14. 27
Replies: 1
Views: 150

Re: HW 14. 27

You probably have to subtract the E(anode) from the E(cathode).
by Matthew Lee 3L
Fri Feb 09, 2018 12:00 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: 9.47
Replies: 1
Views: 177

Re: 9.47

The delta s would come from the system itself.
by Matthew Lee 3L
Fri Feb 09, 2018 11:58 am
Forum: Administrative Questions and Class Announcements
Topic: Lecture Slides
Replies: 6
Views: 513

Re: Lecture Slides

I do not believe he does, unfortunately.
by Matthew Lee 3L
Wed Jan 31, 2018 1:37 am
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: 9.13 [ENDORSED]
Replies: 1
Views: 160

9.13 [ENDORSED]

For question 9.13, the question requires two separate calculations of entropy and then the sum of those is the answer. For the change in entropy using temperature, it uses the constant R in the equation instead of C like it does on the formula sheet. Is this because there is no constant pressure or ...
by Matthew Lee 3L
Wed Jan 31, 2018 1:23 am
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: 9.11 [ENDORSED]
Replies: 3
Views: 261

9.11 [ENDORSED]

For this question, we have to change use pressure instead of volume for the formlua deltaS=nRln(V2/V1) and it says we just use the inverse relationship of volume and pressure to do (P1/P2) instead of (V2/V1). Is this the only way to solve it or is this the only way?
by Matthew Lee 3L
Tue Jan 30, 2018 6:08 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: heat capacities
Replies: 5
Views: 395

Re: heat capacities

You would use the heat capacity of the ice for the ice and the heat capacity of the water for the water.
by Matthew Lee 3L
Wed Jan 24, 2018 11:51 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Exercise 8.39
Replies: 2
Views: 103

Re: Exercise 8.39

It is the empirically found amount of energy to melt solid water (ice) into liquid form.
by Matthew Lee 3L
Wed Jan 24, 2018 11:46 pm
Forum: Calculating Work of Expansion
Topic: Irreversible expansion
Replies: 4
Views: 238

Re: Irreversible expansion

The system is not in equilibrium in an irreversible expansion, because unlike in a reversible expansion, the pressure is reduced quickly, allowing the gas to expand and do work on the external pressure. I'm not entirely sure why it is called irreversible though.
by Matthew Lee 3L
Wed Jan 24, 2018 11:19 pm
Forum: Phase Changes & Related Calculations
Topic: HW 8.1
Replies: 3
Views: 243

Re: HW 8.1

The reason it is an open system is because energy/matter is able to escape the system most likely, in this case, in the form of gas.
by Matthew Lee 3L
Thu Jan 18, 2018 5:52 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Heat Capacity for Constant Pressure and Constant Volume
Replies: 2
Views: 128

Re: Heat Capacity for Constant Pressure and Constant Volume

I'm not entirely sure if we need to know them, but they are on the formula sheet so you don't need to memorize them.
by Matthew Lee 3L
Thu Jan 18, 2018 5:51 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Heat vs. Enthalpy
Replies: 5
Views: 238

Heat vs. Enthalpy

What is exactly is the difference between heat and enthalpy?
by Matthew Lee 3L
Thu Jan 18, 2018 5:42 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: 8.25
Replies: 2
Views: 170

8.25

I'm having trouble on problem 8.25. I'm not sure what it's exactly asking and how to solve it. Thanks! A constant-volume calorimeter was calibrated by carrying out a reaction known to release 3.50 kJ of heat in 0.200 L of solution in the calorimeter (q= -3.50 kJ), resulting in a temperature rise of ...
by Matthew Lee 3L
Wed Jan 10, 2018 3:26 pm
Forum: Phase Changes & Related Calculations
Topic: Enthalpy is a state property
Replies: 13
Views: 809

Enthalpy is a state property

What does it mean that enthalpy is a state property?
by Matthew Lee 3L
Wed Jan 10, 2018 3:07 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Change in Enthalpy of the Reverse Reaction
Replies: 5
Views: 1699

Re: Change in Enthalpy of the Reverse Reaction

I believe you would just take the negative of the enthalpy if you are taking the reverse reaction.
by Matthew Lee 3L
Wed Jan 10, 2018 3:05 pm
Forum: Phase Changes & Related Calculations
Topic: Heat and Phase Transition
Replies: 3
Views: 256

Re: Heat and Phase Transition

According to zonalandeducation.com "During a change in state the heat energy is used to change the bonding between the molecules. In the case of melting, added energy is used to break the bonds between the molecules. In the case of freezing, energy is subtracted as the molecules bond to one ano...
by Matthew Lee 3L
Thu Dec 07, 2017 9:18 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Percentage Deprotonation
Replies: 4
Views: 1996

Re: Percentage Deprotonation

Percentage deprotonation is the percentage of the acid that dissociates and donates an H+ ion.
by Matthew Lee 3L
Thu Dec 07, 2017 9:13 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: 12.55(a)
Replies: 1
Views: 120

Re: 12.55(a)

Because CH3COOH is a weak acid, there is not much change in the concentration of CH3COOH. It does not dissociate very much. Thus, you can just ignore it and treat it as negligible.
by Matthew Lee 3L
Thu Nov 30, 2017 12:05 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Quotient
Replies: 3
Views: 391

Quotient

Is Q basically the same thing as K or are they different?
by Matthew Lee 3L
Wed Nov 29, 2017 11:51 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Enthalpy
Replies: 1
Views: 172

Re: Bond Enthalpy

Bond enthalpy (also known as bond energy) is defined as the amount of energy required to break one mole of the stated bond.
by Matthew Lee 3L
Sat Nov 18, 2017 4:02 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Ligands
Replies: 2
Views: 158

Re: Ligands

The bonds have to be formed with the central atom of the ligand, because the other atoms attached to the ligands are not able to bond anymore.
by Matthew Lee 3L
Sat Nov 18, 2017 3:57 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Chapter 4 Hw , 4.15A
Replies: 2
Views: 330

Re: Chapter 4 Hw , 4.15A

The molecule is not going to be just 2D. The 3D structure would be a tetrahedral which would give bond angles of about 109.5 degrees.
by Matthew Lee 3L
Fri Nov 17, 2017 2:22 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Configuration of Gallium
Replies: 3
Views: 2040

Re: Electron Configuration of Gallium

I concur with the previous answers. The reason you put the 3d first is because it has the lowest energy. This also makes it easier when creating cations to know which electrons you would remove first.
by Matthew Lee 3L
Fri Nov 17, 2017 2:19 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Ligands
Replies: 2
Views: 177

Re: Ligands

The coordination number is basically just the number of bonds on the central metal atom.
by Matthew Lee 3L
Wed Nov 08, 2017 1:38 am
Forum: Properties of Light
Topic: Amplitude properties
Replies: 4
Views: 453

Re: Amplitude properties

Amplitude does not affect wavelength or frequency. Wavelength and frequency, however, have an inverse relationship, which means as one increases the other decreases.
by Matthew Lee 3L
Wed Nov 08, 2017 1:36 am
Forum: Resonance Structures
Topic: 3.71
Replies: 1
Views: 190

Re: 3.71

You want the formal charges as close to 0 as possible on all of the atoms. Once you have that, you can switch the bonds around, while still keeping the same formal charges, to find the resonance structures which you would then use for the resonance hybrid.
by Matthew Lee 3L
Thu Nov 02, 2017 6:04 pm
Forum: *Particle in a Box
Topic: Test 3
Replies: 1
Views: 485

Test 3

I don't remember this from lecture. Do we need to know this for test 3? :)
by Matthew Lee 3L
Thu Nov 02, 2017 4:31 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Quantum Numbers
Replies: 3
Views: 189

Quantum Numbers

How come n can go all the way up to 7, but l only goes up to 3 because there are only s, p, d, and f orbitals?
by Matthew Lee 3L
Wed Oct 25, 2017 1:17 am
Forum: SI Units, Unit Conversions
Topic: Chemistry
Replies: 3
Views: 358

Re: Chemistry

Once cm is the equivalent of 1.0 x 10^-2 m. The prefix centi means that it is one hundredth. For example, if you want to convert 15 cm into m, you would do 15 x 10^-2, which would give you 0.15 m.
by Matthew Lee 3L
Wed Oct 25, 2017 1:10 am
Forum: Properties of Light
Topic: Problem 1.55
Replies: 4
Views: 389

Re: Problem 1.55

You can do the problem using meters too. To do this, you would need to keep light as 3 x 10^8 m/s and convert 3600 cm^-1 into 360,000 m^-1. Since it is cm^-1 and not cm, you would convert it to a larger number.
by Matthew Lee 3L
Mon Oct 16, 2017 6:31 pm
Forum: Photoelectric Effect
Topic: Post Module #25
Replies: 2
Views: 183

Re: Post Module #25

I agree with Ryan on this one. They found out that the frequency of light affected the energy rather than the intensity, which just increased the number of photons in the beam of light. If you look at the E=hv equation, you can see that as frequency goes up, so does energy. Since h is just a constan...
by Matthew Lee 3L
Mon Oct 16, 2017 6:28 pm
Forum: Properties of Electrons
Topic: Experiments
Replies: 2
Views: 287

Experiments

How well should we know the experiments that we discussed in lecture or that are in the book for quiz 2? Will we need to know small details or just the overall idea of the experiments?
by Matthew Lee 3L
Thu Oct 12, 2017 2:01 am
Forum: Photoelectric Effect
Topic: Problem 1.7 HW
Replies: 4
Views: 350

Problem 1.7 HW

For problem 1.7b, it asks for the wavelength of the x-rays described using picometers (pm). I got the answer of 150 pm. However, in the back of the textbook, it says that the answer is 150 nm. Is this answer in the back a typo or am I doing something wrong?
by Matthew Lee 3L
Thu Oct 12, 2017 1:50 am
Forum: Properties of Light
Topic: Speed of Light [ENDORSED]
Replies: 8
Views: 681

Re: Speed of Light [ENDORSED]

I don't think that it really matters that much. Dr. Lavelle uses 3.00x10^8, so that should work. The 2.998x10^8 should be equally as good or better, since it is closer to the exact speed of light!
by Matthew Lee 3L
Wed Oct 04, 2017 3:54 pm
Forum: SI Units, Unit Conversions
Topic: Molecules [ENDORSED]
Replies: 10
Views: 793

Re: Molecules [ENDORSED]

A mole is a specific amount of something. It is the quantity of Avogadro's number which is 6.022 x 10^23. For example, on the periodic table, it gives the molar mass of all of each element. This means that an element weighs 'x' amount of grams for every mole (6.022 x 10^23) of atoms of that element.
by Matthew Lee 3L
Wed Oct 04, 2017 3:50 pm
Forum: SI Units, Unit Conversions
Topic: Base Units
Replies: 6
Views: 566

Re: Base Units

I think that, like the post above said, if it says in the question what units it wants the answer in, use those units. However, if it does not say what units to use, and it has only base units in the question, I would use the base units just to be safe.

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