Search found 24 matches

by Crystal Eshraghi 2L
Sat Mar 12, 2016 12:41 pm
Forum: *Cycloalkanes
Topic: Question 9A on Winter 2015 Final
Replies: 1
Views: 318

Re: Question 9A on Winter 2015 Final

Because the parent chain always has to include the functional group. In this case, the cycleheptane ring doesn't have the alcohol group directed attached to it, so you have to consider the smaller propane chain to be the parent instead.
by Crystal Eshraghi 2L
Fri Mar 11, 2016 12:01 am
Forum: *Cyclohexanes (Chair, Boat, Geometric Isomers)
Topic: Determining Steric/Torsional Interactions
Replies: 3
Views: 573

Re: Determining Steric/Torsional Interactions

Torsional strain is the strain that exists when atoms are eclipsed with respect to each other. Steric strain, on the other hand, exists when atoms are physically in contact with one another (e.g. flagpole interaction in the boat conformation).
by Crystal Eshraghi 2L
Tue Mar 08, 2016 1:50 am
Forum: Administrative Questions and Class Announcements
Topic: Question about the final
Replies: 1
Views: 388

Re: Question about the final

Yes, Dr. Lavelle mentioned that the questions will be longer than they were on the midterm, but that we should still have more than enough time within the almost 3 hours.
by Crystal Eshraghi 2L
Wed Mar 02, 2016 1:55 am
Forum: *Alkynes
Topic: Parentheses confusion
Replies: 2
Views: 812

Re: Parentheses confusion

If, for example, you have the formula CH3CH2CH(CH3)C(CH3)3, you would be able to see clearly the the CH3 in parenthesis in the middle of the formula is a substituent, since a single carbon can't have four bonds (3 H's and 2 of the C's right next to it). Also, you would always include ONE of the mole...
by Crystal Eshraghi 2L
Thu Feb 25, 2016 7:08 pm
Forum: *Electrophiles
Topic: Memory Tips
Replies: 8
Views: 1086

Re: Memory Tips

You can also think of nucleophiles as being "negative" because both words start with the letter N; thus, having a negative charge would cause the nucleophile to be electron-rich. All you have to do from there is just remember that electrophiles are the opposite of nucleophiles!
by Crystal Eshraghi 2L
Sat Feb 20, 2016 11:35 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: reaction order
Replies: 3
Views: 446

Re: reaction order

You can use the general formula for a rate constant's units to determine this: (M^-(n-1))(s^-1), where n is the order of the reaction. So, starting with a zero-order reaction, the units of k would be M/s. You then just have to divide by M each time you "increase" the order by one.
by Crystal Eshraghi 2L
Thu Feb 18, 2016 12:10 am
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Quiz 2 prep #1
Replies: 3
Views: 444

Re: Quiz 2 prep #1

Yes, A is the reactant and P is the product.
by Crystal Eshraghi 2L
Sun Feb 14, 2016 9:12 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: When to add Pt(s)
Replies: 2
Views: 2744

Re: When to add Pt(s)

You only add Platinum to the cell diagram/redox reaction when there is no solid already in the anode or in the cathode of the cell. In this case, you would just add Pt (s) to whichever portion does not already have a solid. If both the anode and cathode are without solids, then you would add Pt (s) ...
by Crystal Eshraghi 2L
Sat Feb 06, 2016 12:23 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: cathodes and anodes
Replies: 1
Views: 286

Re: cathodes and anodes

For the most part, the cathode should be on the right and the anode on the left. However, if the question specifies that it is the opposite, you should just remember to do all of your calculations with the specified orientation in mind. Basically, if it doesn't specify, assume that the cathode is on...
by Crystal Eshraghi 2L
Thu Jan 28, 2016 2:01 am
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Reversible vs. Irreversible
Replies: 1
Views: 284

Re: Reversible vs. Irreversible

I think that in regards to entropy calculations, the question itself should tell you that an isothermal, reversible process is occurring. For reversible reactions then, use the equation .
by Crystal Eshraghi 2L
Thu Jan 21, 2016 9:48 pm
Forum: Calculating Work of Expansion
Topic: Specific heat capacity and molar heat capacity
Replies: 3
Views: 1684

Re: Specific heat capacity and molar heat capacity

Specific heat capacity and molar heat capacity are essentially the same concept -- the only different is that specific heat capacity (Csp) deals with mass in terms of grams while molar heat capacity (Cm) deals with mass in terms of moles. Heat capacity, however, does not account for the substance's ...
by Crystal Eshraghi 2L
Thu Jan 14, 2016 5:26 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Affecting Isolated Systems
Replies: 2
Views: 364

Re: Affecting Isolated Systems

I also believe that there is no way to change the energy of an isolated system -- since you cannot heal or cool such a system, or even compress or expand its volume through work, there seems to be no way to actually alter its internal energy.
by Crystal Eshraghi 2L
Fri Jan 08, 2016 9:08 pm
Forum: Phase Changes & Related Calculations
Topic: Dividing Heat Capacity
Replies: 2
Views: 308

Re: Dividing Heat Capacity

From what I understood from lecture, heat capacity in its intensive form is more useful because it allows us to know the actual, specific amount of substance being dealt with. As an extensive property, however, we are not sure how "large" the object of interest actually is, and so our over...
by Crystal Eshraghi 2L
Mon Nov 30, 2015 2:51 pm
Forum: Identifying Acidic & Basic Salts
Topic: Exceptions of anions
Replies: 2
Views: 469

Re: Exceptions of anions

Because they are both derived from strong polyprotic acids (H2SO4 and H2PO4), meaning that their parent acids can donate more than one proton. As a result, HSO4- and H2PO4- are considered weak acids in contrast to their strong parent acids, but can still donate a proton even though it will be much h...
by Crystal Eshraghi 2L
Wed Nov 25, 2015 1:45 am
Forum: Amphoteric Compounds
Topic: Location of amphoteric compounds in periodic table?
Replies: 2
Views: 777

Re: Location of amphoteric compounds in periodic table?

For the most part, non-metal oxides will always be acidic and metal oxides (particularly the transition metals) will always be basic. So whatever is left over (i.e. the metalloids: Be, Si, Ge, As, Sb, Te, Po) exhibits both acidic and basic properties and thus forms amphoteric compounds.
by Crystal Eshraghi 2L
Thu Nov 19, 2015 2:30 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Volume and Concentration
Replies: 2
Views: 336

Re: Volume and Concentration

If you decrease the volume, the pressure increases (from the inverse relationship between pressure and volume in the ideal gas law: PV=nRT). So if you decrease the volume, the side with more moles (let's say the products, for this example) will have its volume more significantly decreased causing th...
by Crystal Eshraghi 2L
Thu Nov 12, 2015 12:04 pm
Forum: Hybridization
Topic: D orbital vs S orbital
Replies: 2
Views: 422

Re: D orbital vs S orbital

In its ground state, the electrons in Chromium's 4s orbital are at a higher energy level, and thus are less stable than the electrons in the 3d orbitals which are at a lower energy level. When electrons are being removed, it is always easier to remove electrons that are at a higher energy level; as ...
by Crystal Eshraghi 2L
Wed Nov 04, 2015 12:19 am
Forum: Dipole Moments
Topic: Polarity of Double Bonds
Replies: 1
Views: 1267

Re: Polarity of Double Bonds

No, for our purposes, as long as the molecule is symmetrical with no lone pairs on the center atom (as in this case, where the molecular shape is tetrahedral and the P has no lone pairs, causing the dipole moments between the P and each O to cancel each other out) the molecule is non-polar.
by Crystal Eshraghi 2L
Mon Oct 26, 2015 9:10 pm
Forum: Ionic & Covalent Bonds
Topic: Cations and Anions [ENDORSED]
Replies: 12
Views: 1095

Re: Cations and Anions [ENDORSED]

A cation is an ion or group of ions (an atom or molecule) with a total positive charge, while an anion is one with a total negative charge.
by Crystal Eshraghi 2L
Tue Oct 20, 2015 9:40 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Spins
Replies: 3
Views: 522

Re: Electron Spins

The point of assigning spin states is to distinguish between the two electrons that can fill each orbital; the +1/2 and -1/2 ms values are essentially arbitrary, as they do not actually describe a physical phenomenon experienced by the electrons but simply serve to clarify which electron is which wh...
by Crystal Eshraghi 2L
Wed Oct 14, 2015 2:03 pm
Forum: Quantum Numbers and The H-Atom
Topic: Spin State
Replies: 3
Views: 512

Re: Spin State

Yes, the spin state orientation for a particular electron in an orbital is arbitrary. However, when you continue to fill the subshell with electrons, placing one electron in each subsequent orbital at a time, these electrons must have the same spin state as the first one's. In accordance with Hund's...
by Crystal Eshraghi 2L
Tue Oct 06, 2015 1:48 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Not understanding the use of ml
Replies: 2
Views: 431

Re: Not understanding the use of ml

From what I understand, ml refers to the magnetic quantum number and determines the orientation of the orbital in question by labeling the different orbitals of a subshell with specific numerical values. Since ml can take the any value within the range of -l to l, each of those values would correspo...
by Crystal Eshraghi 2L
Tue Sep 29, 2015 4:40 pm
Forum: Empirical & Molecular Formulas
Topic: Molecular Formulas
Replies: 3
Views: 765

Re: Molecular Formulas

If the problem directly tells you that the substance consists of 15 g of C, 2 g of H, and 3 g of O, and that the total mass of the substance is 20 g, then yes, you would just directly calculate the appropriate percentage compositions by dividing 15 g by 20 g for the percent composition of C, 2 g by ...
by Crystal Eshraghi 2L
Mon Sep 28, 2015 10:33 pm
Forum: Empirical & Molecular Formulas
Topic: How to find the empirical formula being given only masses?
Replies: 3
Views: 627

Re: How to find the empirical formula being given only masse

Hi Elizabeth! As far as I know, the way you solve this problem is by initially separating your calculations into two steps. You first find the grams of carbon (C) and hydrogen (H) present in the compound in the first chemical reaction of: compound + O2 --> CO2 + H2O by using the apparent molar ratio...

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