01 Dec 2011

Modern Physics - The professor drew the space-time diagram thing. We derived Lorentz transformation equation for velocities and acceleration.

"In any reference frame any measurements made cannot be greater than c. The interpretation can." (something along this line.)

We talked about relativistic mass, which increases with velocity (with respect to the observer's reference frame). There's no point in talking about mass if it's not constant. There is always a reference frame, the "relativistic mass" in which is what naturally we call "mass" (in the classical sense). Apparently (even) Einstein said that "it is better to introduce NO other mass than "the rest mass" m. Instead of introducing M, it is better to mention the expression for the momentum and energy of a body in motion." (so who are we to think otherwise, haha.)

Organic Chemistry - We talked about Hecks Reaction, Suzuki's Reaction and Alkene Metathesis. Focus should be on the catalytic properties of Paladium. Again, read up professor's posting on course website.


Economics - fell asleep.

Hofman Degradation = Hofmann Elimination

Quatenary ammonium salt to tertiary amine and alkene with the attack of a base (OH). (Water as by-product)

Econ2a : Unemployment

Problems in measuring unemployment rate.

Why is it not necessarily an accurate depiction of unemployment in the economy?

1. It is difficult to distinguish between a person who is unemployed and a person who is not in the labor force (not actively seeking job?).

2. Not all unemployment ends with the job seeker finding a job. Almost half of all spells of unemployment end when the unemployed person leaves the labor force.

3. Some people call themselves unemployed to qualify for government aid, or they are working but paid "under the table" (tax evasion).

4. Discouraged workers: Individuals who have given up finding jobs after unsuccessful search.

--------- Mankiw

30 Nov 2011

Modern Physics - (absent) something about Neutrinos - stuff I don't care about.

Organic chemistry - We talked about organometallic compounds, such as R-Li and R-MgCl, the latter traditionally referred to as Grignard reagent.

These compounds are useful and important for the substition of RX with a metal atom changes the carbon atom from being an electrophile to a nucleophile, i.e. electrophilic attacck of the carbon atom may occur more easily.

Coupling reactions.

Displacement reactions.

Note of interest: Lithium compounds came to play much later than magnesium due to greater reactivity and consequently difficult in storage of Lithium and (some of) its compounds.

- read course handouts on webpage to appreciate the significance of these reactions.

These organometallic compounds are sensitive to -OH, -NH2 groups. Thus the relevant reactions need to be carried out under air-free, inert atmosphere.

Intro to Economics -- We talked about Fisher Effect, inflation and the cost of inflation (shoeleather cost, menu cost) etc. Coiner remarked that expected inflation are generally less harmful (something along this line). When inflation is below what was expected, creditors benefit, debtors (penghutang) lose; and vice versa.

Mankiw writes that inflation itself does not necessarily lead to decrease of purchasing power.

Linear Algebra -- We began to see the link between eigenvalues and orthogonality/orthogonal matrix. I was totally lost in the lecture. Need to study the last few subtopics of Eigenvalues.

Carbocation Rearrangement

If you avoid formation of carbocation in your synthesis, you avoid carbocation rearrangement. (advantage of using oxymercuration-reduction route in synthesis of alcohol from alkyl-substituted alkenes.)

Reminder -- Treasure in State Library

1. Calculus books.



2. Astronomy



3. STPM reference books, particularly the Longman series.



4. TOEFL



5. The Right College (near TOEFL guide books).

Alkanes

I intend to turn this blog into my study log.
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Alkanes are saturated alipathic hydrocarbons. All the carbon atoms are bonded to 4 atoms or groups.

Preparation of alkanes:
"The principal source of alkanes is petroleum. Alkanes from this source consist of a mixture of different alkanes according to the chain length." (Koay's organic chem. notes)

1. Hydrogenation of alkenes

C=C + H2 -----(Ni; Pt; Pd)-----> C-C Pressure = 3 atm, temperature = 100'C


2. Hydration of Grignard Reagent

Grignard Reagent can be prepared by the reaction of alkyl halide and Mg in ether. (Koay)
R-X + Mg -----> R-MgX

.....in diethylether. (Tan Yin Toon)

.....by heating alkyl halide, RX and Mg in ether under reflux. (Madamme How, 8/3/10)


The alkane can be obtained by adding the reagent to water or dilute acid. (Koay)

R-MgX + H2O -----> R-H + Mg(OH)X

X = I, Br, Cl (Koay)

This reaction is not useful for mass production. (Koay)


3. Wurtz Reaction (Koay)
"Wurtz Reaction involves the reaction of an alkyl halide with sodium metal, resulting in the lengthening of the carbon chain and formation of sodium halide salt.

2RX + 2Na -----> R-R + 2NaX

This reaction is especially useful in the synthesis of symmetrical alkanes*, i.e. not pentane.

If 2 different alkyl halides are used, a mixture of alkanes will be obtained.

3 CH3CH2Cl + 3 CH3Cl + 6Na -----> CH3CH3 + CH3CH2CH3 + CH3CH2CH2CH3 + 6NaCl


Reactions
1. Combustion
2. Halogenation, in the presence of light.

C-C + Cl2 ------> C-C-Cl + HCl

1. Cl2 ----> 2Cl (chain initiation)

2. Cl + C-C ---> HCl + C-C (radical) (chain propagation)

3. C-C (radical) + Cl2 ---> C-C-Cl + Cl (chain propagation)

4. Cl + Cl ----> Cl2

5. Cl + C-C (radical) ----> C-C-Cl

6. C-C (radical) + C-C(radical) -----> C-C-C-C (butane)

4,5,6 are chain termination steps.

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*It is worth noting that in the latter chapter, we will learn that halogenation of alkenes take place in the absence of light. Light causes the homolytic fission of halogen molecules, splitting them into free radicals, which hinders the addition reaction. (wwechampion, 8/3/10)

* This does not corroborates with YA and Success Chemistry SPM, page 342.

* Koay said, "The addition of halogens to the double bond is easy to be carried out. The reaction takes place in the absence of light."

The confusion arises from here, on whether presence of light will prevent the reaction from occuring.