CHEMISTRY COMMUNITY

Umair Khan 2G

You are essentially right when talking about priority for naming Z and E. Lets start with the right side first The carbon on the right is connected to a hydrogen (not shown) and the rest of the carbon chain. Since the carbon is angled down, the hydrogen must be pointed up. Also, since carbon has a b...

Umair Khan 2G

Reading over my answer, I can I wasn't very clear. Your are right in that double and triple bonds have priority over substituents in all cases. Also double and triple bonds have equal priority. As such, in this example, prioritize the the double bond is given the lower number, because it give the su...

Umair Khan 2G

Based on this molecule, Cl actually has priority. Notice that the name of this compound is (E). This means that the structure is a trans, and that the bigger elements attached to the carbons in the double bond are on opposite sides. If we look at the carbon on the very right, we compare Cl and CH2CH...

Umair Khan 2G

The Arrhenius equation is:
$k=Ae^{\frac{-Ea}{RT}}$
As you increase the value of A, k increases.

Umair Khan 2G

In the Introduction to Organic Chemistry, on pg. 154 the book says "reactions with activation energies below 80 kj/mol can occur at room temperature." Question number 30 is just some organic chemistry concept, there is no math involved from what I can tell.

Umair Khan 2G

Priority goes to the double and triple bonds when numbering and when naming. When both double and triple bonds are present, I believe that double bonds get priority.

Umair Khan 2G

You are right in thinking that in a normal carbon chain a triple bond would get priority over a double and single bond. However, recall that when naming structures and assigning numbers we have to look at the numbering of the substituents first. Since we give chlorine and fluorine the smaller number...

Umair Khan 2G

The example in the course reader and the example Lavelle said in class were for different types of organic compounds. Let's first start with the book. The compound in the course reader is called 4-Ethyl-2-Methyl-1-Propycyclohexane rather than 1-Ethyl-3-Methyl-4-Propylcyclohexane because the first na...

Umair Khan 2G

Since both O2 and NO2 are products, we know that they are being formed, so the rates for both species will be positive. O2 has a rate of 2.28 and and since NO2 to O2 is a 4:1 ratio, if we multiply 2.28 by 4 we get 9.12. 4 NO2 are being formed for each 1 of O2, or the rate of NO2 is 4 times that of O...

Umair Khan 2G

Intermediates are only in reactions that have multiple parts. Given a reaction that satisfies such conditions, we can identify something as an intermediate if we see it formed in one step and then used in another step. In other words, the intermediate is not a reactant or product because it doesn't ...

Umair Khan 2G

The first step we need to do is too write the the full reaction from the cell diagram. We know that the anode is on the left and the cathode is on the right so the 2 half reations are: Anode: Cu_{s} \rightarrow Cu^{2+} + 2e^{-} Cathode: Cu^{2+} + 2e^{-} \rightarrow Cu_{s} Combining these 2 equations...

Umair Khan 2G

Remember from the Nerst Equation: E=E^{0}-\frac{RT}{nF}*ln(Q) and that at equilibrium E^{0}=\frac{RT}{nF}*ln(K) and solving for K, when we change ln to log, we get K=10^{\frac{n*E^{0}}{0.0592}} Since n is always a positive, the only thing that matters is the cell potential. If the Ca...

Umair Khan 2G

Since Hydrogen has a charge and ends up affecting the placement of electrons for the half reaction, it is written in the cell diagram.
H2O isn't reduced or oxidized and because it has no charge it isn't mentioned. H+ isn't reduced or oxidized, but it affects the charge.

Umair Khan 2G

The simple definition of energy is the ability to do work. In class we talked about 3 main ways to change energy: 1. Add or remove a substance 2. Heat or Cool a substance 3. Do work on the system If a substance cools, its motion of particle slows down and it loses energy. And if a substance heats up...

Umair Khan 2G

In a normal battery an anode and cathode is present. The flow of electrons goes from anode to cathode making the anode side very positive and the cathode side very negative. In a short amount of time, less than a few seconds, the anode side gets such a positive gradient that electrons have trouble e...

Umair Khan 2G

First note that the idea that entropy of the universe is always increasing, not necessarily the system. When we do a reaction we can define a system as having "0 entropy" and the process the system goes through can either decrease of increase this arbitrary 0 value. For example, freezing w...

Umair Khan 2G

An irreversible reaction is where the external pressure will always be constant. As such we can use w=-PdV, because the force needed to move something will always be pushing against a constant pressure. This is irreversible because the process can only expand one way: from high pressure toward the a...

Umair Khan 2G

Intensive properties are properties that don't change if the sample size change. Specific heat capacity and molar heat capacity are intensive because in the equations, you divide by the amount of concentration of the substance giving you a per mol or per gram value. For example, if you have a little...

Umair Khan 2G

When your nuclear charge (the z value, also known as the atomic value) is less than 8 the energy difference between the pi is sigma is so close to each other that the pi is filled first. As you go across the periodic table and down groups, the energy difference between sigma and pi grows, and sigma ...

Umair Khan 2G

The Equation for Benzoic Acid is : C_{6}H_{5}COOH + H_{2}O \rightleftharpoons C_{6}H_{5}COO^{-} + H_{3}O^{+} When Hydrochloric Acid is added, which I'm assuming is the question, there is a 100% disassociation, meaning that HCl splits into a proton and Cl-. The proton normally would increase the conc...

Umair Khan 2G

Remember that HCl is a strong acid so it completely dissociates. This mean thats no there is no need for an ice box because whatever the original concentration of HCl is, the value will go to zero. For example if you have 0.1M of HCl you will get .1M of H30+ If you reduce the concentration by 12%, y...

Umair Khan 2G

The majority of polyprotic acids (ones that have multiple protons, or Hydrogens) are considered weak because their Ka2 values are extremely small. For example if we look at H2CO3, the Ka1 value is 10^-7 (which is not that big), however its Ka2 value is 10^-11. Relatively the second value doesn't imp...

Umair Khan 2G

When writing the the name of the compound, aqua is always used for H2O, however water is written as OH2 to show that the oxygen bonds to the transition metal, and not the hydrogen atom. In addition the suffix -ate is added when the coordination compound has a negative charge, as in it is an anion. F...

Umair Khan 2G

The energy of a photon is is Planks constant (h) times the frequency (v), which is equal to E=hv. Work function is just the minimum amount of energy required to remove an electron, also known as threshold energy. In other words, the formula you mention is exactly the same thing as hv=Ek + work funct...

Umair Khan 2G

B2 has 6 electrons that take place in the molecular orbital, 3 from each Boron atom. The first 4 electrons are used in the 2s sigma bond and the 2s sigma anti-bond. This leaves 2 electrons that need to be placed in the molecular orbital. Also, because Boron has a z value of less than 8, the pi orbit...

Umair Khan 2G

The Phosphate ion is written as PO_{4}^{-3} . This means that there are a total of 32 valence electrons for bonding. The central atom is is Phosphorus because it has a lower ionization energy. Surrounding it with all 4 oxygen, we use 32 electrons. However, calculating the formal charge we find out t...

Umair Khan 2G

The problem with the lewis structure is that it shows a 2D image, when in reality the molecule is 3D. With the tetrahedral structure, all the non-central atoms will be 109.5 degrees away from each other, so no matter where you draw the Chlorine atoms, they will technically always be next to each oth...

Umair Khan 2G

Although the way you describe would technically give the structure a lower formal charge, you have to recall that Nitrogen is part of the 2nd group and thus must obey the octet rule because it does not have access to the 3d sub-shell. If Nitrogen double bonds it would be sharing 10 electrons which i...

Umair Khan 2G

Remember that bond angles for the molecules are based off the real structures, which will be 3D. When drawing lewis structures, we can only diagram the 2D of how the molecule will share its electrons, not how they will be shaped/what the bong angles are. The bond angles for structures just have to m...

Umair Khan 2G

Remember that the angular quantum number, l , relates to the shape and can range from 0 to n-1. When l is equal to 0, this is the s-oribtal, or spherical shape which only has 1 orbital. When l is equal to 1, this is the p-oribtal, or the double-lobe which can have 3 different orbitals. When l is equ...

Umair Khan 2G

The electron configuration for carbon can be written both ways, as both notations are correct. When drawing out the electron configuration the first notation is technically correct as it demonstartes that electrons will occupy all the sub-shells before pairing up with each other, however the second ...

Umair Khan 2G

For part c, we use the formula for the photoelectric effect: E(photon) - \Phi = E(kinetic) Since part A gave us the velocity of the ejected electron we can find the E(kinetic) with E(k) = \frac{1}{2}m^{2} v^{2} , with m being the mass of the electron and v being the given velocity. In part B we solv...

CHEMISTRY COMMUNITY

Search found 32 matches

Re: Course Reader: 3,6-Dimethyl-3-Octene

Re: (E)-3-Chloro-4-fluoro-7-methyloct-3-en-5-yne

Re: Assigning Priority to Atoms/Atoms Groups

Re: Relationship b/w A and k (Arrhenius)

Re: number 30 chapter 4 homework

Re: Naming Order

Re: (E)-3-Chloro-4-fluoro-7-methyloct-3-en-5-yne

Re: Numbering for Cycloalkanes

Re: Finding the rate of formation of a reaction 2006MT

Re: Intermediate

Re: Question 14.41 finding Q

Re: k>1

Re: H+ in Galvanic Cell Diagrams

Re: Internal Energy and Temperature

Re: Salt Bridge

Re: Negative Reaction Entropies for Ions

Re: Reversible vs. Irreversible Processes

Re: Intensive properties

Re: M.O

Re: Depronatation

Re: Reduction of Acid 12.19

Re: When to use Ka1 and Ka2?

Re: Iron vs ferrate & oh2

Re: Work Function vs De Broglie

Re: Homework Problem 4.63a

Re: Phosphate Lewis Dot structure

Re: Question 4.25 Polarity of CH2Cl2

Re: HW 3.59

Re: Bond Angles

Re: Chapter 2 Question 27

Re: Hund's rule-Carbon

Re: Problem 1.33 part c