CHEMISTRY COMMUNITY

Crystal Eshraghi 2L

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.

Crystal Eshraghi 2L

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).

Crystal Eshraghi 2L

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.

Crystal Eshraghi 2L

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...

Crystal Eshraghi 2L

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!

Crystal Eshraghi 2L

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.

Crystal Eshraghi 2L

Yes, A is the reactant and P is the product.

Crystal Eshraghi 2L

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) ...

Crystal Eshraghi 2L

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...

Crystal Eshraghi 2L

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 $\Delta S=\frac{q_{rev}}{T}$ .

Crystal Eshraghi 2L

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 ...

Crystal Eshraghi 2L

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.

Crystal Eshraghi 2L

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...

Crystal Eshraghi 2L

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...

Crystal Eshraghi 2L

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.

Crystal Eshraghi 2L

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...

Crystal Eshraghi 2L

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 ...

Crystal Eshraghi 2L

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.

Crystal Eshraghi 2L

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.

Crystal Eshraghi 2L

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...

Crystal Eshraghi 2L

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...

Crystal Eshraghi 2L

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...

Crystal Eshraghi 2L

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 ...

Crystal Eshraghi 2L

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...

CHEMISTRY COMMUNITY

Search found 24 matches

Re: Question 9A on Winter 2015 Final

Re: Determining Steric/Torsional Interactions

Re: Question about the final

Re: Parentheses confusion

Re: Memory Tips

Re: reaction order

Re: Quiz 2 prep #1

Re: When to add Pt(s)

Re: cathodes and anodes

Re: Reversible vs. Irreversible

Re: Specific heat capacity and molar heat capacity

Re: Affecting Isolated Systems

Re: Dividing Heat Capacity

Re: Exceptions of anions

Re: Location of amphoteric compounds in periodic table?

Re: Volume and Concentration

Re: D orbital vs S orbital

Re: Polarity of Double Bonds

Re: Cations and Anions [ENDORSED]

Re: Electron Spins

Re: Spin State

Re: Not understanding the use of ml

Re: Molecular Formulas

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