Search found 24 matches
- Mon Mar 13, 2017 5:41 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Formula Sheet for the Final Exam
- Replies: 5
- Views: 1079
Re: Formula Sheet for the Final Exam
I would assume its identical to the formula sheet in the course reader before the practice exams, see page 125
- Mon Mar 13, 2017 3:17 pm
- Forum: *Cyclopropanes and Cyclobutanes
- Topic: Rotation of cycloalkanes
- Replies: 2
- Views: 1620
Re: Rotation of cycloalkanes
The Carbon atoms in cyclobutane, unlike cyclopropane, can rotate to stagger the hydrogen atoms and relieve torsional strain. Cyclopropane must be planar, and cyclobutane takes a butterfly confirmation because it is more stable this way than as planar.
- Mon Mar 06, 2017 3:48 pm
- Forum: *Identifying Primary, Secondary, Tertiary, Quaternary Carbons, Hydrogens, Nitrogens
- Topic: Naming organic molecules
- Replies: 1
- Views: 1361
Re: Naming organic molecules
its the number of the carbon in the parent chain that the chlorine of butanol is attached to
- Mon Feb 27, 2017 5:45 pm
- Forum: *Organic Reaction Mechanisms in General
- Topic: Naming Organic Molecules
- Replies: 20
- Views: 4243
Re: Naming Organic Molecules
The Introduction to Organic Chemistry text keeps referring to carbocations in Chapter 4. What exactly are these?
- Mon Feb 20, 2017 9:30 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Quiz 2 Winter 2017
- Replies: 160
- Views: 25914
Re: Quiz 2 Winter 2017
Will we need to know the details of radioactive decay?
- Mon Feb 13, 2017 2:49 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Concentration Cells
- Replies: 2
- Views: 574
Re: Concentration Cells
Standard reduction potentials measure the potential difference between two electrodes. If the electrodes are made of the same material there is no difference. The different concentrations of the solutions only affect E cell, not standard E cell. See the diagram on page 53 in the course reader.
- Mon Feb 13, 2017 2:41 pm
- Forum: Balancing Redox Reactions
- Topic: winter 2014 midterm #8
- Replies: 1
- Views: 426
Re: winter 2014 midterm #8
To calculate K the concentration of products must be over concentration reactants. For Ka calculations the H+ concentration value must be on top, so in order to get an total equation producing H+ the equation containing HF must be the anode, even though standard Ecell is negative and therefore not f...
- Mon Feb 06, 2017 5:09 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Enthalpy
- Replies: 4
- Views: 863
Re: Enthalpy
For 14.9a Ce goes from having a charge of +8 to +6, therefore n=2 (be careful to notice stoichiometric coefficients!)
- Mon Jan 30, 2017 2:14 pm
- Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
- Topic: Residual Entropy 3rd Law of Thermodynamics
- Replies: 4
- Views: 1173
Re: Residual Entropy 3rd Law of Thermodynamics
But if 0K was reached would the residual entropy theoretically be zero, or still just infinitely small?
- Mon Jan 23, 2017 11:50 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: chapter 9 question 23
- Replies: 2
- Views: 523
chapter 9 question 23
What does the answer of this question mean when it says that "it would be possible for the molecule to be disordered"?
- Mon Jan 16, 2017 10:59 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Hc and Hf
- Replies: 3
- Views: 1644
Re: Hc and Hf
I believe that Hc is the standard enthalpy of combustion, or the enthalpy change per mole of something burned during combustion. So, I would say it is used for combustion reactions. However, I am unsure if reactants and products must be in standard state. The text book only say "under standard ...
- Mon Jan 16, 2017 4:08 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Hc and Hf
- Replies: 3
- Views: 1644
Re: Hc and Hf
Hf is for standard enthalpy of formation which is the standard reaction enthalpy for forming one mole of a substance from its elements, but only when its elements are in their most stable form. Where have you seen Hc??
- Wed Jan 11, 2017 8:26 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Units for Standard Enthalpy of Reaction
- Replies: 1
- Views: 464
Re: Units for Standard Enthalpy of Reaction
Yes you are correct, they are both kj/mole as it states in our course reader.
- Mon Nov 28, 2016 4:52 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: Chapter 12 Question 69b
- Replies: 2
- Views: 643
Re: Chapter 12 Question 69b
The same reaction is used in question 12.65, I was wondering why it is (h20)6? Why not 5 or 4 or even 3?
- Mon Nov 21, 2016 1:43 pm
- Forum: Conjugate Acids & Bases
- Topic: pH and pOH
- Replies: 4
- Views: 1343
Re: pH and pOH
I've heard that it stands for potential, but other sources say it was just chosen at random. Here is a short article about it.http://cultureofchemistry.fieldofscienc ... ds-ph.html
- Wed Nov 16, 2016 7:15 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Question on 17.31
- Replies: 1
- Views: 563
Re: Question on 17.31
Ligands are supposed to be arranged alphabetically so aqua comes before oxalato!
- Wed Nov 09, 2016 1:10 pm
- Forum: Naming
- Topic: Naming Compounds
- Replies: 2
- Views: 623
Re: Naming Compounds
Unless questions in the homework and the practice quizzes require this knowledge, which I do not believe they do, we do not have to worry about it!
- Mon Oct 31, 2016 4:04 pm
- Forum: Lewis Structures
- Topic: Oxidation Number of Thallium in Tl2O3
- Replies: 3
- Views: 1648
Re: Oxidation Number of Thallium in Tl2O3
The oxidation state of Oxygen is -2 , and since there are three oxygen the overall charge of oxygen in this molecule is -6. Because there are two thallium atoms their charges must each be +3 each to balance the oxidation states.
- Wed Oct 26, 2016 3:07 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Quiz Grades
- Replies: 3
- Views: 938
Re: Quiz Grades
I was wondering if we are able to check quiz grades online? I can't find a CCLE link and the grades section on myUCLA is blank.
- Tue Oct 18, 2016 11:24 am
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 4036510
Re: Post All Chemistry Jokes Here
I heard they're starting a whole new chem channel devoted to as xenon tv products.
- Tue Oct 11, 2016 3:24 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Quizes
- Replies: 21
- Views: 3052
Re: Quizes
Are pencils or pens preferred on quizzes?
- Fri Oct 07, 2016 12:41 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Changing signs [ENDORSED]
- Replies: 2
- Views: 703
Re: Changing signs [ENDORSED]
As to your first question, be sure to stick to the greater than or equal to symbol unless the minimum is asked for, otherwise it could result in lost points. But to your second question you are correct, for example if a problem listed plus or minus six the uncertainty would be tweleve.
- Tue Sep 27, 2016 11:47 pm
- Forum: Limiting Reactant Calculations
- Topic: Combustion Analysis
- Replies: 1
- Views: 673
Re: Combustion Analysis
First, you see in example m4 that the mystery compound contains only Carbon, Hydrogen, and Oxygen. The goal is to find the amount of each of these elements (moles). In terms of variables you need to use the mass of carbon dioxide produced and its molar mass to find the moles of CO2 (n= m/M). Once yo...
- Sun Sep 25, 2016 8:34 pm
- Forum: Empirical & Molecular Formulas
- Topic: Calculating Molecular and Empirica Formulas
- Replies: 5
- Views: 2878
Re: Calculating Molecular and Empirica Formulas
In the audio visual module Professor Lavelle posted about empirical and molecular formulas he mentioned that a 3.89 would be fine to round up to 4 but a decimal more like 3.75 would signal that you need to multiply by something else (four). I would say 3.87 is close enough to 4 to be rounded. Usuall...