JesslynLee's

2010-07-05T23:58:00.000-07:00

I think this is the latest latest post for 2010!!!
Hahahah.
Looking back at the past's blog posts..
Reminds me of memories (like hell lot) and how things have changed. ... ..
Anyway,PRE-U2 spells only one thing.
S-T-R-E-S-S.

2009-09-09T08:31:00.000-07:00

Somehow,looking back at the past months's memories is really comforting and amazing.Be it verbally,written,or drawn.

Ahem.
Throughout the September holidays,i didn't revised much because practically everyday was spent at school,so i was constantly being "spoon-feed" with new knowledge and information instead of doing revisions.Seriously Math's a killer.
As for Chemistry.........Well,i think i am pretty weak at Energy Cycle and Chemical Bonding.
Gotta buck up.

Today's 09/09/09.Is there any good phenomenon for this?

RESEARCH ON M.P TREND ACROSS PERIOD III

2009-08-20T09:12:00.000-07:00

http://www.creative-chemistry.org.uk/alevel/module1/trends8.htm#graph

-Has practically everything you will need to know for it. :-D

2009-08-09T04:28:00.000-07:00

Omg blogger's down with all the html codes missing AGAIN.-.-
Energetics is pretty okay,just need some time to get to the gist of it.Have some more practice,should be fine?
There's going to be a "Timed assignment 6A" for Energetics soon,hopefully i'd be able to score.
Just did finish Chemistry Tutorial..realised i've been neglecting my Physics for quite a bit (A lot?)..gotta buck up..
& MI NDP celebration(dress code:retro) was fun..before and after :P

2009-08-01T23:06:00.000-07:00

Finally,blogger's back with a the html codes for blogging.Am very glad.
Just did some of the Energetics Tut.6 questions,structured questions at the end's a blur.Just hoped that this topic's is gonna be a breeze somehow.. ..

P.s:Jesslyn,you got to face the problem and stop avoiding

2009-08-01T01:41:00.000-07:00

(Another update)
Haven't been touching up on any of the Chemistry Revisions,lazy "High inertia"
Just thought about my future job,though "Journalist" still is appealing,"A private Investigator" would sound more intriguing for me.
Definately discovering the various depths of how evil and the darkest secrets of human beings sounds fun?

P.s:I still need time to be by my side

2009-07-30T04:21:00.000-07:00

Hello,been long since i last updated.Shall give some brief happenings for Chemistry:
#1:Promotional Examinations (1) H2 CHEMISTRY is really badly done in my perspective,excluding the "Overall Results".
#2:Chemistry topics are getting tougher,can sense it.
#3:Shall update about the term ,"Standardization" in this post,since Ms.Gee asked us to do some research for those who are not too clear about the definition.

-Standardization of a solution refers to an experiment in which the concentration of a solution is determined.
-A process in which the value of a potential standard is fixed by a measurement made with respect to a standard whose value is known.

Can't seemed to find any useful definitions!!!!!!!!!!!!

Shall talk about Ideal Gas.
Ideal Gas equation: pV=nRT
p-pressure in Pa
V-volume in m^3
n-amount in mol
R-universal gas constant (8.314)
T-temperature in K

According to the Kinetic Particle theory of gasses, an ideal gas will have:

-Volume of gas particles negligible as compared to volume of the container
-Negligible intermolecular forces between gas particles
-Gas particles are moving in constant random motion
-Gas particles collides in an perfect elastic motion

Shall talk about Energetics:
So far,we had only learnt the various definitions of different types of enthalpy change/energy.For example,Standard enthalpy change of solution,Standard enthalpy change of hydration,Standard enthalpy change of neutralisation,Standard enthalpy change of atomisation,Standard enthalpy change of reaction,Standard enthalpy change of formation,Bond dissociation energy,Lattice energy,Electrons Affinity,etc.Just remember that the standard conditions is 1atm pressure,298K in temperature.

Finally to summarise(with questions!)
Why is enthalpy change for exothermic reactions negative?
Because energy has been released to the surroundings. The products therefore have a lower enthalpy than the reactants and the final enthalpy is less than the initial enthalpy

Why is standard enthalpy changes of combustion always negative?
Because heat is always evolved, the reaction is exothermic and therefore heat is lost to the surroundings. The energy required to break bonds is always less than the energy released when bonds are formed

Alright,see ya guys! :-)
P.s:I am just plain happy and blessed recently,excluding those physical and mental pain.

2009-06-26T06:49:00.000-07:00

Hello teachers,i want to know if it's still necessary to keep this "Chemistry Blog" and if yes,do we still need to keep the updates going on?Thankyou!

2009-04-11T23:26:00.000-07:00

What are the properties of ethanedioic acid that make you think that it is a good choice for standardisation of alkali(NaOH)?(Why we do not use HCl or H2SO4 to standardise)

Is it because that it is,
:a weak acid,pure,stable in air, readily soluble in water and have a relatively large relative formula mass.

:a solid acid whose mass is an accurate measure of the number of moles of H+ ions it will require.

Anyway for extras:
:We cannot prepare standard NaOH solution by dissolving a measured mass of pure NaOH in a known volume of water,because NaOH is
hygroscopic,which means it readily absorbs atmospheric moisture. (Results in inaccurate concentration?)

:The balanced equation for the acid-base reaction involved in the standardization procedure is;
H2C2O4(aq) + 2 NaOH(aq) → Na2C2O4(aq) + 2 H2O(l)

2009-03-31T08:20:00.000-07:00

Ethanedioic acid.

Molecular formula : C2H2O4 /C2H2O4 .2H2O (?)
MW : 90.04
CAS No. :144-62-7

Nature transparent colorless crystals or a white powder, odorless, The findings. 1.650g/cm3 density. 101 ° C melting point. The boiling point of 150 ° C (sublimation). Slightly soluble in water, soluble in water, alcohol, ether-soluble, non-soluble in benzene. In dry air heating or small crystal water will be lost. The organic acids are strong acid, alkali and the Sino-and role. With reductive. With sulfuric acid role lose moisture, the foundation decomposed into dioxide and carbon monoxide. And the role of oxidant easily oxidized into carbon dioxide and water. Toxic to the skin, mucous membrane and stimulate corrosion vulnerable by the epidermis, mucosal absorption cause poisoning. Air maximum allowable concentration of 1m g/m3.

2009-03-23T09:28:00.000-07:00

My goodness.It's really suffocating and tedious for me since I have no background of whatsoever the "orbital" thing is about in the new topic,Atomic Structure.
First of all,i was lucky because i had my sister's notes(which was a miracle she didn't threw it yet),which aided a lot on my study for this topic.Secondly,i really don't understand anything when Mr Tan explained roughly on the topic to the class (So sorry!) It's my fault,haven't been reading up
So,apparently,chemistry's taking a hell lot of my sleeping time.haha.

Back to the main reason for this post,..

Protons(p) is positioned in nucleus,with +1electric charge,relative mass of 1.
Neutron(n) is positioned in the nucleus,with 0
electric charge,relative mass of 1.
Electron(e^-) is positioned around the nucleus,with -1 electric charge,relative mass of 1/1840.

Principal quantum numbers >No of energy lvl>e.g (n=1,n=2....)
Types of subshells: s,p,d,f. (Mr tan said we only need to learn up to s,p,d)
The sequence goes, 1s^2,2s^2,2p^6,3s^2,3p^6,3d^10
When drawn in boxes,(electron-in-boxes method).................each box can draw up to 2 electrons.
By which their spins is always opposite,starting from up arrows,followed by downward arrows
1s have the lowest energy,4f-the highest,however to take note,3d has higher energy than 4s

shapes of orbitals for s,-spherical
shapes of orbitals for p(px,pz,py)-Dumb-bell
Different aces of symmetry,mutually,perpendicular to one another,orbitals (px,py,pz) with the same p.q.n have the same energy,ie.they are degenerate

the laws/rules to follow:
1)Pauli Exclusion Principle
2)Aufbau (for building up) Principle
3)Hund's Rule

Ok,i typed this all out because i find the online notes gave quite a lot redundant information.(ops) haha.It's quite messy though,sorry Ms Jee/Mr Tan

As for Ionisation Energies,NEXT TIME PLEASE!

2009-03-21T20:07:00.000-07:00

Question:How does the equivalence point of a titration differ from its end point?

Answer:
The equivalence point is the point where the number of moles of base equal the number of moles of acid. The end point is the point where the indicator being used changes color. If the indicator is chosen correctly, the end point will essentially be exactly at the equivalence point. The point of the titration is to find the equivalence point -- the end point is just a very close approximation to it. This is because the pH of the solution changes very rapidly close to the equivalence point. Therefore, the indicator will change colour very close to the equivalence point because of the steepness of the pH change.

I understood now,clearly!
C:
C:
C:

2009-03-20T00:09:00.001-07:00

Ohhhh..I've just realised my dates and time's so screwed up.
And it's cool,because that meant that i woke up on 4.12a.m(previous post) just to post an entry.
Now now,how hardworking am i?HAHA

2009-03-16T04:12:00.000-07:00

Well hello there!
This entry's gonna be on my choosen career,which was like for now,a journalist.
First of all,on lighter note,let me elaborate on why i wanted to be one.
The reasons is fairly simple.1)I like writing,a lot. 2)I like to have updates on the latest news. 3)I like anything related with english language! 4)Working alone sounded quite fun(i guess....) As quoted,"Traditionally, journalists have more or less worked alone."

Okok..
Now..Let's go into much formal stuffs...like what it is all about!

Journalists in both the news business and feature writers for magazines typically will develop their stories, dig up their leads, conduct their interviews and draft the final product themselves. In the newspaper business, major stories will sometimes become collaborative efforts where several reporters are working on aspects of a story and their work is edited into a single piece, published under multiple bylines.

Ok..Job requirements!(generally)

Responsibilities:
-Gather, edit, write & voice the daily news & sports bulletins
-Ensure that the quality of news & sports bulletins is of a high standard, accurate & credible
-Conduct roving reports & interviews for news
-Cover assignments & produce capsules for radio news
Entry Requirements:
-Diploma or Degree in Mass Communications, Journalism, Chinese Studies or Political Science
-Preferably 1 year of experience in journalism or related field
Attributes:
-Passionate in news writing with keen interests in current affairs & sports
-Writes well & able to work under pressure.
-Ability to read and write in English is an advantage
-Mature, independent & has initiative.

Ok..I know it's a bit far-fetched from what i'm studying now(SCIENCE STREAM) which was like a bit unrelated..But well,i can't get in mass communication in NgeeAnnPoly in the first place,not as if i don't want to ):
Sad huh?!But i believe,just believe that....Nothing's impossible!(yeah!good phrase to quote!thanks Nike! C:)----EDIT,BY ADIDAS,(thanks to Mr.Kensei.)

2009-03-10T06:54:00.001-07:00

Weakness in chemistry:
Can't balance equations fast enough.
Takes quite some time in analysing questions.

Strength in chemistry:
I've no idea?The best result i've ever gotten in certain topics?
& my strength in chemistry is that i like chemistry.:D

2009-03-02T08:40:00.000-08:00

Reflection:
I learnt the different tips and precautions to take note of.
And how to use experimental equipments safely and properly and rightly.

2009-02-23T22:20:00.000-08:00

I've learnt... (In binary covalent nomenclature tutorial)
-Converting Formulas to Names

-. Organic compounds, like methane, CH4, ethane, C2H6, and propane, C3H8, are named by a systematic procedure.

-
water - H2O
ammonia - NH3
methane - CH4
ethane - C2H6
propane - C3H8

I've learnt... (In cation names and formulas tutorial)
-Metallic atoms hold some of their electrons relatively loosely, and as a result, they tend to lose electrons and form cations. In contrast, nonmetallic atoms attract electrons more strongly than metallic atoms, and so nonmetals tend to gain electrons and form anions.

-The fact that the noble gas atoms do not gain, lose, or share their electrons suggests there must be something especially stable about having 2 (helium, He), 10 (neon, Ne), 18 (argon, Ar), 36 (krypton, Kr), 54 (xenon, Xe), or 86 (radon, Rn) electrons.

-The names of monatomic cations always start with the name of the metal, sometimes followed by a Roman numeral to indicate the charge of the ion. For example, Cu+ is copper(I), and Cu2+ is copper(II).

I've learnt... (Anions names and formulas tutorial)
-Metallic atoms hold some of their electrons relatively loosely, and as a result, they tend to lose electrons and form cations.

-The positive cations and the negative anions attract each other to form ionic bonds.

-Polyatomic ions are named with the word hydrogen in front of the name of the anion if there is one H+ ion attached and dihydrogen in front of the name of the anion if two H+ ions are attached.

I've learnt...(in ionic nonenclature tutorial)
-Metal‑nonmetal: Ionic compounds whose formula contains one symbol for a metal and one symbol for a nonmetal are called binary ionic compounds.

-Metal‑polyatomic ion: Polyatomic ions can take the place of monatomic anions, so formulas that contain a symbol for a metallic element and the formula for a polyatomic ion represent ionic compounds.

-Ammonium‑nonmetal or ammonium‑polyatomic ion: Ammonium ions, NH4+, can take the place of metallic cations in an ionic compound, so chemical formulas that contain the formula for ammonium with either a symbol for a nonmetallic element or a formula for a polyatomic ion represent ionic compounds.

I've learnt..(in Balancing Chemical Equations Tutorial)
-
Consider the first element listed in the first formula in the equation.
If this element is mentioned in two or more formulas on the same side of the arrow, skip it until after the other elements are balanced.
If this element is mentioned in one formula on each side of the arrow, balance it by placing coefficients in front of one or both of these formulas.
Moving from left to right, repeat the process for each element.
When you place a number in front of a formula that contains an element you tried to balance previously, recheck that element and put its atoms back in balance.
Continue this process until the number of atoms of each element is balanced.

2009-02-23T04:26:00.000-08:00

My first entry.
Went to O Hub during chemistry's lesson.