Search found 20 matches
- Fri Mar 17, 2017 11:47 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Calculating Work
- Replies: 1
- Views: 404
Re: Calculating Work
If you're referring to question 2b from Quiz 1, you can use the formula W = -nRTln(v2/v1) and plug in the given values, as indicated by the information on Course Reader p. 31.
- Fri Mar 10, 2017 10:38 am
- Forum: *Alkanes
- Topic: Reaction Profiles
- Replies: 3
- Views: 698
Re: Reaction Profiles
This can also be distinguished by a positive or negative standard reaction Gibbs free energy value. If this value is negative, it is a favorable exergonic reaction. If the value is positive, there is an unfavorable endergonic reaction.
- Wed Mar 01, 2017 10:12 pm
- Forum: *Electrophiles
- Topic: Examples of electrophiles in course reader
- Replies: 1
- Views: 581
Re: Examples of electrophiles in course reader
Alkyl halides are compounds where the H atoms normally bonded to C are replaced by halogens, so CH3Cl, CH2Cl2, CH3Br, etc.
Carbonyls are compounds that have CO functional groups replace H atoms, so (CH3)2CO, CH3CO, CH2(CO)2, etc.
Carbonyls are compounds that have CO functional groups replace H atoms, so (CH3)2CO, CH3CO, CH2(CO)2, etc.
- Sun Feb 26, 2017 6:06 pm
- Forum: *Cycloalkenes
- Topic: Self test 1.11A question b
- Replies: 1
- Views: 428
Re: Self test 1.11A question b
On page 28, it says carbon numbering is first determined by the double bond, then by the alkyl substituents. So the numbering of the carbon bonds goes counterclockwise so that the double bonds include the lower numbered carbon atoms (1-2 and 4-5) and the functional group also still included the lowe...
- Tue Feb 14, 2017 5:54 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Quiz 1
- Replies: 5
- Views: 1032
Re: Quiz 1
Dr. Lavelle waits until the end of the quarter when the scores from the 3 quizzes, midterm, online discussion, and final are totaled up (out of 400 points) and assigns grades based on the class average.
- Wed Feb 08, 2017 12:04 am
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Winter 2015 Midterm question 2and 3c
- Replies: 2
- Views: 604
Re: Winter 2015 Midterm question 2and 3c
In part B, 84 kJ/mol was the enthalpy of the reaction for 2 moles of H2O, so 42 kJ/mol is the standard enthalpy for 1 mole of H2O, which you would then use as the value of standard enthalpy in calculating the the standard enthalpy of formation of HI.
- Mon Jan 30, 2017 10:01 am
- Forum: General Science Questions
- Topic: Sig Figs with Logs
- Replies: 2
- Views: 1589
Re: Sig Figs with Logs
The course reader uses "mantissa" when explaining sig figs for logarithm problems. This term refers to the digits after the decimal point, so since 10^2.18 has 2 sig figs after the decimal point, there will be 2 sig figs in the final decimal answer written in scientific notation, 1.5x10^2.
- Thu Jan 26, 2017 11:42 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Quiz1 Prep
- Replies: 1
- Views: 459
Re: Quiz1 Prep
I believe Chemistry Moderator posted in previous threads indicating that answers would not be posted in order to encourage students to work together and determine the correct answers.
- Sat Jan 21, 2017 12:22 pm
- Forum: Significant Figures
- Topic: Sig Figs
- Replies: 8
- Views: 3422
Re: Sig Figs
There are additional significant figure examples about addition, subtraction, multiplication, and division, as well as rounding and logarithms on pages 122-123 in the Course Reader.
- Fri Jan 13, 2017 10:10 am
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Standard Enthalpy Question
- Replies: 4
- Views: 773
Re: Standard Enthalpy Question
Hello, I believe they used those reactions (O2 --> O2, Br2 --> Br2) since they demonstrate that the standard enthalpy of formation is 0. Since the reactants and products are identical, as you mentioned, no additional energy is needed to break or form bonds, and therefore no heat is being absorbed or...
- Sun Nov 27, 2016 7:50 pm
- Forum: Bronsted Acids & Bases
- Topic: Distinction between Bronsted and Lewis
- Replies: 2
- Views: 714
Re: Distinction between Bronsted and Lewis
I believe Bronsted acids and bases concern protons, while Lewis acids and bases concern electrons. A Bronsted base will accept a proton while a Lewis acid will accept an electron pair.
- Fri Nov 25, 2016 3:10 pm
- Forum: Bronsted Acids & Bases
- Topic: Weak Acid
- Replies: 4
- Views: 1051
Re: Weak Acid
Since HF has a smaller atomic bond, wouldn't that mean it has a shorter bond length, which is why it is a weaker acid and harder to break the bond?
- Fri Nov 25, 2016 3:05 pm
- Forum: Student Social/Study Group
- Topic: RE: Final Study Group
- Replies: 1
- Views: 627
Re: RE: Final Study Group
Hello! I'm up for studying this week! My lounge probably isn't the most ideal as it's usually filled with people studying.
- Fri Nov 25, 2016 3:03 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3006675
Re: Post All Chemistry Jokes Here
Good luck with finals, everyone!
- Thu Nov 10, 2016 9:30 am
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3006675
Re: Post All Chemistry Jokes Here
I asked the guy sitting next to me in lecture yesterday if he had any Sodium Hypobromite…
He said NaBrO. :(
He said NaBrO. :(
- Wed Oct 26, 2016 4:50 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Quiz Grades
- Replies: 3
- Views: 903
Re: Quiz Grades
I just checked my grades on UCLA and it has my Quiz 1 score posted. MyUCLA > Classes > Exam and Homework Grades
- Tue Oct 18, 2016 4:58 pm
- Forum: Trends in The Periodic Table
- Topic: Grouping of Valence Electrons [ENDORSED]
- Replies: 3
- Views: 1514
Re: Grouping of Valence Electrons [ENDORSED]
Hello Parsia,
Pb has 4 valence electrons since its valence shell (n=6) has 4 electrons. The 6s and 6p sub-shells are both holding 2 electrons, which means the 6s orbital is full, but the 6p orbitals still have room for 4 additional electrons.
Pb has 4 valence electrons since its valence shell (n=6) has 4 electrons. The 6s and 6p sub-shells are both holding 2 electrons, which means the 6s orbital is full, but the 6p orbitals still have room for 4 additional electrons.
- Mon Oct 17, 2016 10:02 pm
- Forum: Hybridization
- Topic: Memorization Tricks
- Replies: 9
- Views: 5331
Re: Memorization Tricks
My high school chemistry teacher taught us "King Henry died by drinking chocolate milk", so pretty similar to what everyone else has been suggesting.
- Fri Oct 07, 2016 10:10 am
- Forum: Administrative Questions and Class Announcements
- Topic: Scantrons?
- Replies: 2
- Views: 544
Re: Scantrons?
During my discussion session yesterday, my TA didn't mention anything about scantrons and said we could complete our quiz in pen so I am assuming we don't need to purchase Scantrons. Do you know where to purchase Scrantons if we end up needing them for a future exam?
- Fri Oct 07, 2016 10:06 am
- Forum: Student Social/Study Group
- Topic: Rieber Hall 14A Study Group (Fall 2016)
- Replies: 49
- Views: 9842
Re: Rieber Hall 14A Study Group (Fall 2016)
Hello everyone!
I'm from Rieber Terrace, but it appears we don't have a study group at this time. I'm interested joining you all and wanted to know the next time you were planning to get together. Thanks!
I'm from Rieber Terrace, but it appears we don't have a study group at this time. I'm interested joining you all and wanted to know the next time you were planning to get together. Thanks!