## Search found 21 matches

Sat Mar 18, 2017 9:26 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Winter 2016 Final, Q6
Replies: 1
Views: 289

### Re: Winter 2016 Final, Q6

I assume you're talking about Question 6B. In that case, the nucleophilic O- from the OH- is attacking the electrophilic C. When the electrons are transferred to the C, they get taken by the Br, because it is more electrophilic, and the C-Br bond breaks, leaving Br- by itself and OH to bond to the s...
Thu Mar 16, 2017 7:56 pm
Forum: *Alkanes and Substituted Alkanes (Staggered, Eclipsed, Gauche, Anti, Newman Projections)
Topic: Relative Energy Differences?
Replies: 1
Views: 435

### Re: Relative Energy Differences?

I don't believe we need to memorize the energy differences, we just need to know which conformation has less energy and is more stable.
Thu Mar 16, 2017 5:47 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Winter 2015 Final Q1-D
Replies: 1
Views: 342

### Re: Winter 2015 Final Q1-D

Yes, because the question states that 5 g of bread provides 2,000 kcal. Also, when you're looking at bomb calorimeters, the equation you use is q=CdeltaT, so the mass is not needed to calculate the q.
Sun Mar 05, 2017 2:06 pm
Forum: *Cycloalkanes
Topic: Homework problem 1.16 cycloalkane naming
Replies: 3
Views: 434

### Re: Homework problem 1.16 cycloalkane naming

I started numbering at the two methyls at the top of the cyclopentane and went around clockwise until i got 5. In the end i got
1,1-dimethyl-2-isopropylcyclopentane. I hope this helps.
Thu Feb 23, 2017 7:35 pm
Forum: Administrative Questions and Class Announcements
Topic: Quiz 2 Winter 2017
Replies: 160
Views: 17079

### Re: Quiz 2 Winter 2017

This might be dumb question, but could someone quickly explain the difference between the reaction rate and the rate constant? The reaction rate is the rate at which the reaction proceeds, dependent on the rate constant (k) and the concentrations of the reactants. The rate constant is a an independ...
Mon Feb 20, 2017 7:19 pm
Forum: Zero Order Reactions
Topic: Zero Order Classification [ENDORSED]
Replies: 2
Views: 514

### Re: Zero Order Classification[ENDORSED]

So zero-order reactions occur when the rate is unaffected by the concentration of the reactants. So when there is an extremely little amount of a reactant, a zero-order reaction can occur, though it basically never happens in anything but a laboratory setting.
Hope this helps!
Thu Feb 09, 2017 5:46 pm
Forum: First Order Reactions
Topic: Half life?
Replies: 2
Views: 412

### Re: Half life?

I think we still need to know them. Just know the equations t1/2=ln2/(wavelength) and N(t)=N0e^-(wavelength)(time)
Thu Feb 09, 2017 5:41 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: hw:14.107 Relation of K and H+/OH-
Replies: 1
Views: 254

### Re: hw:14.107 Relation of K and H+/OH-

In some galvanic cells, the reaction H2O -> H + OH is part of the oxidation/reduction reaction. So the H+ is part of the reduction reaction at the cathode and the OH- is part of the oxidation reaction at the anode. At the end, after you solve the problem, you'll end up with H + OH -> H2O as the fina...
Thu Jan 26, 2017 6:41 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Equipartition Theorem
Replies: 2
Views: 468

### Re: Equipartition Theorem

Basically, the equipartition theorem states that systems in thermal equilibrium distribute energy evenly throughout the system. From this, you can calculate the average amount of energy and heat in a system.
Thu Jan 19, 2017 5:20 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: which bonds to break/form [ENDORSED]
Replies: 2
Views: 350

### Re: which bonds to break/form[ENDORSED]

Hi! I'm pretty sure you will get the same answer if you calculate every bond that breaks and forms, it will just take a bit longer to get the answer. However, your answer should still be correct, you just have to make sure to write all the bonds out to make sure you include all the necessary informa...
Thu Jan 12, 2017 4:05 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Reaction Enthalpies
Replies: 1
Views: 246

### Re: Reaction Enthalpies

Standard reaction enthalpy is the enthalpy change of the reaction under standard conditions. So if the problem is not under standard conditions, you would just calculate the enthalpy change. Hope this helps.
Thu Dec 01, 2016 4:17 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: Ka values in multiple reactions
Replies: 1
Views: 915

### Re: Ka values in multiple reactions

Yes, there are several reactions when dealing with polyprotic acids. For example, H2CO3 would have two separate reactions, in which one proton would be donated each time. For the second part of your question, I believe you multiply the Kas together because the overall K value works like it would in ...
Thu Nov 24, 2016 4:58 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Why is BF3 an acid?
Replies: 2
Views: 1734

### Re: Why is BF3 an acid?

In addition to the answer above, the three fluorides are very electronegative and therefore cause B to be very electrophilic (induction effect). This results in a higher stability when attacked by a nucleophile (Lewis base). Essentially B in BF3 acts as a Lewis acid because it wants to accept the Le...
Thu Nov 17, 2016 5:11 pm
Forum: Ideal Gases
Topic: Two forms of M.O. Diagrams
Replies: 1
Views: 316

### Re: Two forms of M.O. Diagrams

When Z<8 the sigma pz and pi orbitals switch because the sigma bond has higher energy than the pi bond. That's why the sigma is at a higher state than the pi bond. But when Z>8, the sigma bond has a lower energy level than the pi bond and is therefore lower.
Sun Nov 13, 2016 11:03 am
Forum: Ideal Gases
Topic: Concept of Ideal Gas
Replies: 1
Views: 344

### Re: Concept of Ideal Gas

Basically, we assume the gasses we are dealing with are ideal gases to make our calculations less complex. Ideal gases are at standard temperature and pressure, only collide elastically, which means kinetic energy and momentum are conserved, and take up a certain volume. They are theoretical. Hope t...
Thu Nov 03, 2016 4:05 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Molecular Orbital Configuration: px/py?
Replies: 1
Views: 377

### Re: Molecular Orbital Configuration: px/py?

On tests and quizzes, I would probably differentiate and write (pipx)2 and (pipy)2 as separate entities. They both have the same energy level because they are both sub shells in the p orbital. The x and the y correspond to the ml quantum number. This notation tells you that a pi bond forms in the px...
Thu Oct 27, 2016 4:02 pm
Forum: Lewis Structures
Topic: Formal Charge vs Octet Rule
Replies: 3
Views: 1277

### Re: Formal Charge vs Octet Rule

I would say formal charge especially because P is a Period 3 element, which means it is an exception to the octet rule.
Thu Oct 20, 2016 4:43 pm
Forum: Lewis Structures
Topic: Chap 3 Q 59 [ENDORSED]
Replies: 2
Views: 492

### Re: Chap 3 Q 59[ENDORSED]

By drawing the Lewis Structure and calculating the formal charge, you can see that chlorine and oxygen share a double bond with chlorine having the unpaired electron. Chlorine is one of the exceptions to the octet rule, whereas oxygen usually just has an octet. For this structure, the formal charge ...
Mon Oct 17, 2016 4:33 pm
Forum: Ionic & Covalent Bonds
Topic: 25.b [ENDORSED]
Replies: 1
Views: 259

### Re: 25.b[ENDORSED]

On question 3.25 b, the problem asks for Indium (III) Sulfide. So, Indium would have a charge of +3 and Sulfur would have a charge of -2. Therefore, to balance charges, the chemical formula would be In2S3.
Sun Oct 09, 2016 11:03 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Ch. 1 HW #43
Replies: 1
Views: 358

### Re: Ch. 1 HW #43

This basically means that you can picture the atom as a defined shape (a box). By looking at an atom this way, you can determine the uncertainty in position (delta x) of the electron, which would be equal to the diameter of the atom, and plug it into the Heisenberg uncertainty equation.
Sun Oct 02, 2016 11:47 am
Forum: Properties of Light
Topic: Chapter 1 Homework Question [ENDORSED]
Replies: 7
Views: 2772

### Chapter 1 Homework Question[ENDORSED]

The question in the textbook is as follows: Which of the following happens when the frequency of electromagnetic radiation decreases? Explain your reasoning. (a) The speed of the radiation decreases. (b) The wavelength of the radiation decreases. (c) The extent of the change in the electrical field ...