## Search found 51 matches

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)
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!
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')?
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.
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.
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?
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?
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.
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.
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.
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.
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.
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.
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.
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.
Fri Feb 16, 2018 12:06 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Nernst Equation 2.303RT/F = .059V
Replies: 4
Views: 3275

### Re: Nernst Equation 2.303RT/F = .059V

I would also like to know where the 2.303 came from. Thanks!
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).
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.
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.
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 ...
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?
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.
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.
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.
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.
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.
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?
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 ...
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?
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.
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...
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.
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.
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?
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.
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.
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.
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.
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.
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.
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.
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? :)
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?
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.
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.
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...
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?
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?
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!
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.
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.