CHEMISTRY COMMUNITY

Mikaela Gareeb 3G

Dr. Lavelle, Thank you for not only helping me understand chemistry better, but also for helping ease the transition from high school into college. You have been understanding every step of the way and have supported me, as well as your thousands of other students, in this exciting, yet nerve-wracki...

Mikaela Gareeb 3G

If you're not part of the solution, you're part of the precipitate.

What's "HIJKLMNO"?
H2O

Why does a hamburger have lower energy than a steak?
It's in the ground state

Mikaela Gareeb 3G

Electrophilic addition reactions are always two step mechanisms (and therefore always have two transition states). On the other hand SN2 reactions are all one step reactions with one transition state.

Mikaela Gareeb 3G

Did you hear about the guy who got cooled to absolute zero ?
He's 0K now

What's a girl's future best friend?
Carbon
C (graphite) -> C (diamond)

Mikaela Gareeb 3G

Common names apply to specific molecules, but Lavelle said that he's not going to specify the type of naming that we must do (IUPAC vs common), so we can just use IUPAC any time a question asks to name a molecule.

Mikaela Gareeb 3G

What do you call iron blowing in the wind?
Febreze

What do dipoles say in passing"
"Have you got a moment?"

Mikaela Gareeb 3G

The question will clarify which elementary reaction is faster and slower because you can't determine that by just looking at the steps.

Mikaela Gareeb 3G

We know that step two is going to be the slow step because there is going to be a buildup of the intermediate from step one; therefore, because step one is progressing so quickly, there will be a bottle-neck effect.

Mikaela Gareeb 3G

Kb would apply to a basic reaction, so I assume that you would solve it the same way as you would for an acidic reaction.

Mikaela Gareeb 3G

The electrode (inert conductor) should sandwich the molecules being oxidized and reduced, but other than that the order of the molecules within the anode and cathode does not matter. It's important to know where to put the lines that separate the molecules- draw a line when the molecules are in diff...

Mikaela Gareeb 3G

An optimist sees the glass half-full and a pessimist sees the glass-half empty, but the chemist sees the glass half-filled with liquid and half-filled with gas... unless the system is in a vacuum.

Mikaela Gareeb 3G

First, you must create an equation in which the only product is N2O5 by manipulating the two given equations. Once you attain the standard enthalpy of the reaction for your new equation, solve for the standard enthalpy of formation for N2O5 by using the formula: DeltaH = 2DeltaH(N2O5) - 3DeltaH(O2)-...

Mikaela Gareeb 3G

DeltaS=q/T = DeltaH/T = ((1.00 mol)(-6.01 kJ/mol))/(273.2 K).
-6.01 kJ/mol is the enthalpy of fusion (melting), and since freezing is the opposite of melting you just take the negative of delta H. Also, the freezing point of water is at 273.2 K- both of these values are found in table 8.3.

Mikaela Gareeb 3G

You're adding up the enthalpies of the reaction. You are given an equation and the enthalpies of combustion for each of the individual molecules, so when you create a combustion equation for each of the molecules (remember that combustion is a molecule + oxygen -> carbon dioxide + water) you will ha...

Mikaela Gareeb 3G

I'm not sure why the solution manual doesn't break the C-H bonds that are on the reactants side (as well as the products side), but this is how I did it: break 1 C-C triple bond: (3 mol)(837 kJ/mol) break 2 H-C single bonds: (3 mol)(412 kJ/mol) form 6 C-C resonance bonds: -(6 mol)(518 kJ/mol) form 6...

Mikaela Gareeb 3G

When HCl and NaOH react with each other, H2O and NaCl form, but because NaCl is a salt, it doesn't react with anything. Whenever you are using density, you should also use specific heat capacity because density times volume equals mass which can be multiplied by specific heat capacity and temperatur...

Mikaela Gareeb 3G

I found the UA hours especially helpful because there are so many of them, but also because there are fewer people there so you can ask more questions. Also, since the UAs are usually third- or forth-years they can give you practice problems from earlier versions of the course reader.

Mikaela Gareeb 3G

I think we need to know what they are (weak acids that change color when the stoichiometric point is reached), but when I asked Lavelle during office hours, he said that we don't need to know the colors.

Mikaela Gareeb 3G

If the reaction is endothermic (requires heat), then heating the equation will favor products (forward reaction) whereas if the reaction is exothermic (releases heat), then heating will favor reactants (reverse reaction). Also, since pressure and volume are inversely proportional (as pressure increa...

Mikaela Gareeb 3G

The question is asking for the pH of NH4Cl (an acidic salt) and because it dissociates into NH3 and H3O+, we need to find the concentration of H3O+ by doing an ICE chart. At equilibrium we find that the concentration of of H3O+ is x, and by solving for x we get 9.2e-6, so by using the equation pH=-l...

Mikaela Gareeb 3G

If you are given an ion such as NO+ and are told to draw the MO diagram for it, which atom would the electron be taken from? Would the N have one less electron because it is less electronegative than O and therefore able to lose an electron more easily?

Mikaela Gareeb 3G

What kind of fish is made out of two sodium atoms?
Tuna (2Na)

Mikaela Gareeb 3G

CO:(sigma 2s)^2 (sigma 2s*)^2 (pi 2p)^4 (sigma 2p)^22. Bond order=3
CO+: (sigma 2s)^2 (sigma 2s*)^2 (pi 2p)^4 (sigma 2p)^11. Bond order=2.5
Because CO has a higher bond order, it has a stronger bond.

Mikaela Gareeb 3G

Whats the chemical formula for banana?
BaNa2

Mikaela Gareeb 3G

Lavelle said that the best way to study for the midterm is by reviewing the past two quizzes which means that the midterm would be up to chapter three. However, I'm not sure if he would put anything from chapter four on the midterm, but if I hear anything I'll update this post.

Mikaela Gareeb 3G

H, He, Li, and Be do not follow the octet rule. Also, B can form less than an octet, such as BF3, but it can also attain an extra electron to fulfill the octet rule, such as BF4^-

Mikaela Gareeb 3G

It's possible to have resonance structures in which the resonance occurs with different elements so long as, in this case, nitrogen and oxygen do not have expanded octets. Also, be aware of the formal charge; if the compound is neutral and double bonding the nitrogen or oxygen gives you an overall n...

Mikaela Gareeb 3G

Radicals will react with an electron from a DNA molecule and oxidize it, but antioxidants (like the ones in blueberries) catch radicals before the can cause damage.

Mikaela Gareeb 3G

For all equations that include joules use kilograms- this includes the De Broglie equation and Heisenberg Uncertainty Principle. Also, always use liters for molarity. To remember to convert units just look at the units you want in your answer and keep in mind that 1 J = 1 kg*m^2/s^2.

Mikaela Gareeb 3G

For the chapter one homework questions, it asked to determine the type of electromagnetic radiation from the wavelength calculated, so I would assume that we should know the different regions for the quiz next week.

Mikaela Gareeb 3G

Total energy-threshold energy=excess energy describes the photoelectric effect in steps. In other words, a certain amount of energy is inputed by a photon and the process of removing an electron takes up some energy, but if there is some left over, then the electron takes the excess/kinetic energy w...

CHEMISTRY COMMUNITY

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Re: Saying Thank You to Dr. Lavelle

Re: Post All Chemistry Jokes Here

Re: Electrophilic Addition Example in Quiz 3 Prep

Re: Post All Chemistry Jokes Here

Re: IUPAC vs. Common names

Re: Post All Chemistry Jokes Here

Re: Speed of reaction

Re: Pre-Equilibrium Approach

Re: Finding Ka

Re: Cell Diagrams

Re: Post All Chemistry Jokes Here

Re: 8.65

Re: Homework Question 9.15 (a)

Re: 8.57

Re: Homework 8.73 a

Re: Calorimeter questions

Re: Most Helpful Resource

Re: Importance of Indicators

Re: chemical equilibrium

Re: page 161 of the course reader

MO diagrams for ions

Re: Post All Chemistry Jokes Here

Re: 4.61 Homework Question

Re: Post All Chemistry Jokes Here

Re: MidTerm Review [ENDORSED]

Re: Lewis Structure Octet Rule Exceptions

Re: Resonance structures [ENDORSED]

Re: Radicals

Re: Conversions

Re: Atomic Spectra Requirements [ENDORSED]

Re: Kinetic Energy