Search found 22 matches
- Tue Mar 08, 2016 2:43 pm
- Forum: *Constitutional and Geometric Isomers (cis, Z and trans, E)
- Topic: 1.26, 28, and 29
- Replies: 2
- Views: 429
Re: 1.26, 28, and 29
To clarify, for naming an organic compound with a double bond and indicating “E” or “Z”, there will always be a longest chain on each side of the double bond. Alternatively, you may be naming “E” or “Z” with a functional group on either side of the double bond, be sure to look up a list priorities o...
- Wed Mar 02, 2016 2:26 pm
- Forum: *Alkanes
- Topic: is HI a nucleophile or electrophile
- Replies: 1
- Views: 2609
is HI a nucleophile or electrophile
Hello! Is the molecule HI considered a nucleophile or an electrophile? I- is a nucleophile, I is an electrophile, and HI has lone pairs, so shouldn't it be a nucleophile? However HBr (a similar molecule) is an electrophile so should HI be an electrophile?
- Tue Mar 01, 2016 12:22 pm
- Forum: *Alkanes
- Topic: Identifying substituents in the molecular formula
- Replies: 3
- Views: 532
Re: Identifying substituents in the molecular formula
Hello, double bonds take priority over alkanes, so you would need to start on the side of the molecule that would get you to number the double bond first. It doesn’t matter if the double bond is part of the main chain or just a substituent, you still need to start numbering so that you can get to it...
- Tue Feb 23, 2016 3:42 pm
- Forum: *Alkanes
- Topic: Naming Clarification
- Replies: 3
- Views: 615
Re: Naming Clarification
When naming a non-cyclic organic compound, the first thing you should do is determine your base chain. This is the longest possible chain from head to tail (the structure and the way it is drawn can mislead you from picking the longest chain though). Then, you determine which side of your base chain...
- Thu Feb 18, 2016 1:38 pm
- Forum: Second Order Reactions
- Topic: Units for Second Order
- Replies: 2
- Views: 968
Re: Units for Second Order
The units of k can be really helpful in a problem because they can tell you what overall order of reaction you have without even knowing any other information! For any order reaction, the units of k will always be such that the rate of the reaction equals “mol/(L*sec)” or concentration/time. So for ...
- Thu Feb 11, 2016 7:35 am
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: q=?
- Replies: 2
- Views: 474
Re: q=?
I’ve seen that you commonly use the equation q=C(deltaT) when you are calculating the heat for a calorimeter (qcal=C(deltaT)). It’s also important to remember that qcal=-qsystem. Most other times, you use q=mC(deltaT) or q=nC(deltaT), depending if you are given heat capacities in g or moles. I hope ...
- Wed Feb 03, 2016 3:04 pm
- Forum: Balancing Redox Reactions
- Topic: Half-Reactions
- Replies: 3
- Views: 538
Re: Half-Reactions
You will have to balance your own half reactions sometimes without being able to look them up in an Appendix. Here is a set of rules for balancing redox reactions. For balancing in an acidic solution: 1. Divide the equation into two half reactions. 2. Balance any atom other than O or H first. 3. Bal...
- Wed Jan 27, 2016 4:58 pm
- Forum: Phase Changes & Related Calculations
- Topic: Quick significant figures question
- Replies: 4
- Views: 859
Re: Quick significant figures question
I think you only base significant figures on the values used in your calculations. (So if you didn’t actually use the value 4.2g in any of your calculations, you wouldn’t use it for determining the amount of sig figs in your answer). Additionally, it is helpful to know that you go through your entir...
- Wed Jan 20, 2016 10:33 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Degeneracy equation
- Replies: 2
- Views: 540
Re: Degeneracy equation
In order to find the molar residual entropy of a system, you must use the equation S=kB ln W, where S is the molar residual entropy of the system, kB is Boltzman’s constant (1.3806 x10^-23 J/K), and W is the degeneracy of the system. I like to think of W as the number of microstates possible for the...
- Thu Jan 14, 2016 7:00 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: QUIZ 1 Material
- Replies: 7
- Views: 1089
QUIZ 1 Material
Hello,
I was wondering if Chapter 11 material (assigned in the syllabus) would be part of Quiz 1 material? Thank you very much!
I was wondering if Chapter 11 material (assigned in the syllabus) would be part of Quiz 1 material? Thank you very much!
- Wed Jan 13, 2016 2:21 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: 8.73 Bond Enthalpy of Benzene
- Replies: 4
- Views: 5193
Re: 8.73 Bond Enthalpy of Benzene
For Problem 8.73 and any other problem involving calculating reaction enthalpy using bond enthalpies, you need to look up tables (Table 8.7 in this case) for the bond enthalpies of the bonds being broken and formed. The total reaction enthalpy will be equal to all of the bonds being broken subtracte...
- Wed Jan 13, 2016 2:18 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Mean Bond Enthalpy
- Replies: 2
- Views: 763
Re: Mean Bond Enthalpy
You’re right, there is only one mole of water molecules in the reaction, however each water molecule is made up of TWO H-O bonds (think about the Lewis structure). That is why you need to multiply the bond enthalpy for the H-O bond by 2. I hope this helps!
- Wed Jan 06, 2016 3:38 pm
- Forum: Phase Changes & Related Calculations
- Topic: Enthalpy values
- Replies: 2
- Views: 564
Re: Enthalpy values
Hello, In order to find the enthalpy of a reaction using bond enthalpies, you will need to have a chart of all bond enthalpies at hand (something like Tables 8.6 or 8.7 on Page 300 of our textbook). Then, it is important to know that the enthalpy of the reaction will be the difference between the bo...
- Tue Dec 01, 2015 6:26 pm
- Forum: Acidity & Basicity Constants and The Conjugate Seesaw
- Topic: Using the formula
- Replies: 2
- Views: 703
Re: Using the formula
For answering questions regarding acids/bases, I have memorized these equations. It is true that Kw=1.0*10^-14 at 25C. Additionally, you will have to be given at least one other piece of information specific to the question in order to correctly solve the other variables, such as pH, pOH, pKa, pKb, ...
- Mon Nov 23, 2015 3:02 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Strong Acid/Base
- Replies: 2
- Views: 412
Re: Strong Acid/Base
Also, strong acids have higher Ka values, so they dissociate almost 100%, while weak acids have very low Ka values, which makes them only partially dissociate in solution.
- Wed Nov 18, 2015 8:26 pm
- Forum: Ideal Gases
- Topic: Question about Kp vs Kc
- Replies: 2
- Views: 707
Re: Question about Kp vs Kc
Hello, this is true. And another thing that may be useful to mention here is a way to convert Kc to Kp (or vice versa). To do this, you use the equation given in the textbook on Page 438, where Kp= [ (cRT/P)^(delta n) ] *Kc. I hope this helps!
- Wed Nov 11, 2015 10:38 pm
- Forum: Biological Examples
- Topic: Other Biologically Important Coordination Compounds
- Replies: 1
- Views: 556
Other Biologically Important Coordination Compounds
I was wondering what other coordination compounds are important in biological systems? For example, in our course reader, Dr. Lavelle talks about the heme molecule being an iron-based coordination compound. Also, I found on-line that Vitamin B is also a coordination compound with a cobalt metal cent...
- Tue Nov 03, 2015 3:09 pm
- Forum: Ionic & Covalent Bonds
- Topic: Midterm 2011 question 6B
- Replies: 2
- Views: 923
Re: Midterm 2011 question 6B
In order to rank compounds in terms of their relative ionic character, one needs to first understand the spectrum of covalent and ionic comounds. Covalent compounds share electrons, and the closer together two atoms’ electronegativities are, the better they will share their electrons. Similarly, the...
- Sat Oct 31, 2015 7:33 am
- Forum: Limiting Reactant Calculations
- Topic: Limiting Reactants & Limiting Reagents [ENDORSED]
- Replies: 7
- Views: 3140
Re: Limiting Reactants & Limiting Reagents [ENDORSED]
I have made one educational chemistry video about the limiting reactant calculation. Thank you very much. -Aya Ghoneum
- Wed Oct 28, 2015 4:22 pm
- Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
- Topic: OF+
- Replies: 2
- Views: 6681
Re: OF+
The bond order and magnetism (paramagnetic or diamagnetic) found through molecular orbital theory is not always reflected in the Lewis structure for a molecule. Lewis structures are strictly based on valence electrons and the octet rule. They give a generic understanding of the molecule, mainly help...
- Thu Oct 22, 2015 8:13 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Polar vs Nonpolar
- Replies: 3
- Views: 3944
Re: Polar vs Nonpolar
One easy way to differentiate if a molecule is polar would be that any molecules with at least one lone pair on the central atom is polar. If there are no lone pairs on the central atom and all of the surrounding atoms are equivalent, then the molecule is non-polar. If there are nonequivalent atoms ...
- Mon Oct 05, 2015 3:05 pm
- Forum: DeBroglie Equation
- Topic: Atomic Spectra and Rydberg Question
- Replies: 1
- Views: 479
Atomic Spectra and Rydberg Question
For the homework question 1.15, "In the ultraviolet spectrum of atomic hydrogen, a line is observed at 102.6 nm. Determine the values of n for the initial and ending energy levels of the electron during the emission of energy that leads to this spectral line." can I assume that the ending ...