轻舟已过万重山 -

Passione V ;

2010-12-12T20:57:00.001+08:00

(: ;

2010-05-29T18:25:00.003+08:00

Food & Hotel Asia ;

2010-04-26T13:11:00.000+08:00

my 20 at Kbox ;

2010-04-02T23:10:00.003+08:00

Happy Birthday to myself ;
Happy Birthday to myself ;
Happy Birthday to myself ;
Happy Birthday to myself .

Thankyoo Laodou - Jasline
Thankyoo Baomu - Zhenghuang
Thankyoo Ahyi - MeiShan

I had a wonderful night. with the K-box session, the surprise self-made cake from yoo guys. Love yoo all loads! touch* (:

movie & breakfast ;

2010-03-20T13:08:00.000+08:00

Last shot inside the theater right after the movie -Kaiji. [ handsome Tatsuya Fujiwara ! ]

outside hall 2. we got chased out because no camera is allowed inside !

actually wanted to play bowl. but ii got no socks! zzz. so we choose to take a few pics [ is free ]

den head home.

ii am a good citizen. ii don't play with such a thing. however, is me who asked them to take picture with such pose! hahas. !!

The starting point of our journey. we are going to walk back from here to my house. because is alr 2.30am & we choose not to take cab as we can exercise! Total distance = 4.5km. estimated using my iPhone map, it requires 57mins to walk back !

However, we reached back ard 3.20am. [ is a long long straight journey ]

my breakfast. [ hot cakes with saussage ] + ice milo without ice. >.<

if yoo see closer, the boy wearing the blue shirt. It printed '' ii am on a strict diet'' behind. & why the hell is he appearing at mac?! arent him on diet? hahas. !

& my last shot. my breakfast with kave's lunch. oh ya. almost forget. her mac spicy double really HOT !!! is too spicy for me.! she still say, 'really?!'

omg~

dinner out with Fiona ;

2010-03-15T23:39:00.003+08:00

today was my first day of March-Holiday. I stayed at home doing homework till quite fed-up. & so, thinking of having ppl to accompany me for dinner. well. I dunno why ii decided to ask 'Luo han yu' out. hahas. maybe she working at Paya Lebar & is quite near from my house.

I meet up with her at Singapore Post. Intend to eat Long John Silver but she wanted to eat mac! so went in to find seats. while waiting for our dinner to be ready, sth happen to Fiona! LOL. [ inside joke , only me, her and the mac employee who served us know ! ]

after my dinner, out of curiosity, ii explored Fiona's wallet. & saw that one of the change she got back from the Mac cashier was a Ten-ringgit. hahas! & ii helped her changed it back.
after dinner, went toilet ... & have a few shots via my iPhone. (:

& we went to This Fashion to shop. I got myself two lingerie ! [ red + black ]

before heading home, we have a few more shots ! *above

well ~ dere goes a day. tmr got phy lesson !

teo heng outing ;

2010-02-26T10:34:00.009+08:00

went Tanjong Katong shopping centre with bestie Jamie & her bestie Hiro ;
Teo heng family KTV !!
we have fun guessing their mascot & got it - ans is penguine ! hahas ;
sing from 6pm to 9pm & off to play pool ;
after that , we have dinner - wan tan mee !!
bus 40 backed to Bedok and changed to 168 with Hiro.
afterall , had a tired day but it was enjoyable !
ii will miss my sister when she's gone ~
but we will meet up again when she is back!
takecare, my 2yrs plus bestie ! (:

outing day ;

2010-01-23T23:30:00.002+08:00

Last weekday outing before sch reopens ;

2010-01-08T23:13:00.002+08:00

nights out ;

2010-01-06T23:56:00.001+08:00

a night out with buddy , Jamie ;
had Heineken & Tiger with two plates of peanuts ;
windy night with full of laughter ;

awaiiting ;

2010-01-04T23:52:00.001+08:00

Random ;

2009-12-31T19:43:00.003+08:00

Love does not only compose of happiness but also sadness and hurt.
It hurts when yoo cut a piece of your heart to seal a hole in mine, and in the same way ii do for yoo.
That is why I’m in your heart, and yoo are in mine always ~

zahrah's celebration ;

2009-12-31T14:39:00.012+08:00

us with bdae girl ; sister ; me me and me ;
Jonathan and waEne ;

the bestie ; pull your ears ; Girls' rule ; Jamie's star & moon ; Bella and Alice ; Jamie and Chinfang ;
LJH ;
Zahrah and Jamie ;
Jamie and Jiahui ; me & Jonathan & Jamie ; the banana ; playing with dale ; the bdae girl ; Zahrah and me ; Zahrah and Chinfang ;
my leggies ; ii look so funny ;
Jiahui . always the last to finish her meal ;
Tomato Chicken Pasta ;
Jamaican Jerk Spice ; Black Pepper Chicken Steak ; Minced Beef Steak ; Lunch place at Tampines 1 ;

TO ZAHRAH :
Happy 18th Birthday. Although is kind of very belated celebration [ cos yoo're nt around ] , we still hope yoo had enjoyed yourself & well , love the presents too~

Team Building Day ;

2009-12-24T17:35:00.004+08:00

badminton ;

2009-12-22T18:45:00.002+08:00

take a break from badminton ;

clark quay ;

2009-12-21T00:47:00.003+08:00

forever and on ;

2009-12-16T14:21:00.003+08:00

what is a home ?

a place to have a shelter ?
a bed for yoo to sleep ?
a bathe room for yoo to clean up yourself ?
a enclose 'freedom' prison?

what is a home actually ?

forever and on ;

2009-12-16T14:02:00.004+08:00

the pain tore me apart
until yoo came and fixed my broken heart

ii guess everyone needs a way out & yoo say there’s no escape but take my hand so we can fly away together forever and ever again ;

forever and on

can yoo feel that?

we’re really doing it

for the first time in our lives

we seem to be flying ;

this is one hell of a ride

so lets do this together

we’ll get through together

forever and on

brace yourself now

just hold on tight now

tighter then ever ;

forever and on

& just thinking about

seeing your face or hearing your voice

takes the tears away

& they say yoo are the best thing that ever happened to me

we’re simply meant to be ;

now this is one hell of a miracle

so lets do this together

we’ll get through together

forever and on

brace yourself now

just hold on tight now

tighter then ever ;

[ 不能說的秘密 ]

male versus female ;

2009-12-14T11:07:00.004+08:00

He is domesticated and home-loving enough to provide a secure care for the restless house lady. On the other hand , she is happy and affable enough to complement his depressed moods. He may be jealous and possessive while she is independent and impulsive but she is not sensitive enough to take his self-pitying ways too seriously. She is capable , delightful and quick at catching onto delicate signals. He could curb her freedom by providing her with enough variety and attractive options to stay and spice up his life.

with this ; A strong and possible enduring marriage will last forever ~

ii love yoo ;

2009-12-13T14:18:00.002+08:00

跟隨著音符踏上旅程﹐第一眼就決定了緣份。當旅途走到了終點時﹐回去的路就藏在急速的旋律中。

[ 愛是不是不開口才珍貴 ? ]

Lurb Love Luv ;

2009-12-13T11:30:00.002+08:00

What is love ?
An emotion so stong and so pure that nurtured and shared with another ;
What is love ?
A force to bring the mighty low , with the strength to shade the mountains and half time ceaseless flow ;
What is love ?
A triumph , a glorious goal attained the union of two souls , two hearts , a bond the angels have or dained ;
What is love ?
A champion to cast the tyrant from its toe and wave the flag of truth and peace and fear of death over it or throw ;
What is love ?
A reason to guide the way towards heart , a blazing light upon the shoals that dash cherished dreams apart ;
What is love ?
Forever , eternal and sincere , a flame that through war and lane will outline life brief years ;

so ii will fell if on top of the mountains , in all places high and low , that LOVE for yoo is my reason to be and will neber break or bow ;
I thought LOVE was just a mirage of the mind . It's an illusion , it's fake , impossible to find but the day I met yoo .
I began to see that LOVE is real and exists in me ;

awaiiting ;

2009-12-09T18:57:00.008+08:00

LIFE . . .

生活就在於知道如何去享受一點點
而忍受許許多多。
每天給自己多一點自信。
即使生活有一千個理由讓你哭
你也有一千零一個理由笑。

awaiiting.

2009-12-06T23:15:00.001+08:00

人生自是有情痴 ﹔
此恨不關風與月。

Life yoo may evade but death yoo shall not ;

2009-12-06T12:00:00.002+08:00

A stranger yoo were once then with a gentle look . yoo took my hand.
As our lives engaged . yoo lit my life and I held both your hands.
Now that decades have passed . our soul have indeed become one.
How fortunate we are that we have found the love so true that everyone dreams about?

Lurve ;

2009-12-02T11:48:00.004+08:00

A special world for yoo and me. A special bond one cannot see. It wraps us up in its cocoon and holds up fiercely in its womb.
Its fingers spread like fine spun gold. Gently nestling us to the fold. Like silken thread it holds us fast. Bonds like this are meant to last.
And though at times, a thread may break, a new one forms in its wake. To bind us closer and keep us strong. In a special world where we belong.
A gentle world like a spark of light, illuminates my soul. And of each sound goes deeper, it's your devotion that makes them still.
And yes, yoo always speak to me in sweet honesty and truth. Your caring heart keeps out the rain, your love, the ultimate roof.
So , thank yoo, my love for being there for supporting me, my life. I'll do the same for yoo. Yoo know, my beloved, my love.

vivo ;

2009-11-20T23:53:00.001+08:00

vivo city night view ;

final destination ;

2009-08-31T18:09:00.003+08:00

random ;

2009-08-02T14:25:00.001+08:00

me ; me ; is me !

study ;

2009-07-06T23:20:00.002+08:00

take a break from studying ;

chemistry assignment ;

2009-06-20T22:48:00.001+08:00

awaiiting.

2009-06-02T17:52:00.001+08:00

awaiiting.

2009-06-02T17:51:00.001+08:00

chemistry ;

2009-04-08T22:46:00.001+08:00

Reaction kinetics ;

2009-04-08T20:40:00.003+08:00

Reaction Kinetics

A) Explain the use of terms: Rate of reaction; rate equation; order of reaction; rate constant; half-life of a reaction; activation energy; catalysis.

Rate of reaction: The rate of reaction is defined as how fast a reaction takes place.
Rate Equation: The rate equation shows how the rate of the reaction is dependent on the concentration of the reactants.
Order of Reaction: The order of reaction is the power of the concentration of the reactants.
Rate Constant: The rate constant is a constant of proportionality in the rate equation. The rate constant is only affected by temperature.
Half Life of a Reaction: The half-life of a reaction describes the time needed for half of the reactant to be depleted.
Activation Energy: The energy needed to overcome so that the reaction will take place.
Catalysis: Catalysis is the process where the rate of reaction is being increased by the catalyst.

B) Construct and use rate equations of the form rate = k [A]a [B]b (a & b can represent any numbers.) Part I) Deducing the order of reaction by the initial rates method. First, write the ratio of the rate laws for two trials.
r1r2
=
k [A]1a [B]1bk [A]2a [B]2b
Next, substitute the numerical values into the equation. ( The numbers are examples only. You can find the true numbers at the table in your question)
2.73 mole L-1 sec-16.14 mole L-1 sec-1
=
k (0.100 mole L-1)a (0.100 mole L-1)bk (0.150 mole L-1)a (0.100 mole L-1)b
Notice that the units for each quantity and the rate constant can be removed, and in this case the exponent b is removed when the concentrations of B divide. The equation simplifies to
2.736.14
=
0.100a0.150a
0.4446 = 0.6667a
To convert a from an exponent into a coefficient, take the logarithm of both sides of the equation.
ln[0.4446] = ln[0.6667a]
-0.8106 = -0.4054a
The value of a may now be readily determined.
a =
-0.8106-0.4054
=2

The order of reaction of a is 2! So if 2 it means it’s second order of reaction. If a is 1 then it’s first order of reaction.
Part II) Justifying, for zero and first order reactions, the order of reactions from concentration-time graphs. For Zero order of reactions: It would mean that the reaction proceeds at a constant rate, the decrease of the reactants will be constant. This would mean that the concentration time graph will be a straight line that is sloping downwards. For First order of reactions: There is a half life reaction in first order of reaction, so the rate of the graph is constant. The reactants are being reduced by half of the previous concentration. This would show that the concentration time graph is a slope downwards, characterized by having half of the reactants from the previous concentration, in the continuous same amount of time.

Part III) Calculating an initial rate using concentration data. This can be done if we know the rate equation and a value for k (which can either be derived from the above formula or known on its own). Then it is just a matter of putting the values into the equations and working out the answer.D) Explain qualitatively, in terms of collisions, the effect of concentration changes on the rate of a reaction. As concentration increases, there will be more particles in the reaction, thus increasing the frequency of effective collisions, which leads to a higher rate of reaction. Reaction Kinetics (Learning outcome)

Rate of reaction is affected by
concentration of reactant
temperature
catalyst
surface area of reactant

For a reaction to take place, the reactant particles must possess sufficient activation energy to break existing bonds with the correct orientation to bring reactive sites close together.

Activation energy is the minimum amount of energy that reactant particles must possess in order to react.

Below is the activation energy level diagram.
The rate of reation increases as the concentration of reactants is increased. Rate is proportional to reactant.

The concentration of reactants will increase the frequency of collisions between particles and this increases the rate of reaction. The rate started off the fastest at the beginning and gradually decreases as the reactant are gradually used up. It stops when one of more reactants are used up.
Below shows the graph of the rate of reaction of the reactant against time.

For gaseous system, an increase in pressure increases the rate of reaction. This is because molecules are brought closer together and they collide more frequently.

The rate of reaction increases as the temperature increases. A 10 C rise in temperature approximately doubles the rate of reaction.

This is because increasing the temperature will increase the average kinetic energy of the molecules, resulting in more collisions per unit time. There is an increase in the proportion of molecules with energy equal to or greater than the activation energy, Ea, required for the reaction. Below is the Boltsmann-distributive curve.
Ea
Energy E
Fraction of molecules with energy E
T2 ( >T1)
T1
Fraction of molecules with energy>Ea at T2
Fraction of molecules with energy>Ea at T1

A catalyst is a substance which alters the rate of a reaction but is left chemically unchanged at the end of the reaction.

In most of the reactions, a catalyst is added to speed up the reaction; i.e to increase the rate of reaction.

Catalysts are usually only required in small amount.
Catalysts generally increase the rate constant (k) for the reaction. Catalyst do not initiate the reaction; it usually accelerate a reaction that is already occurring.

A catalyst works by providing an alternative reaction pathway of lower activation energy, Ea so that more molecules would now have energy >Ea

Lower activation energy would result in a larger rate constant,k, and hence a faster reaction.
Ea
Ea’
Fraction of molecules with energy > Ea for catalysed reaction
Fraction of molecules with energy > Ea for uncatalysed reaction
Energy E
Fraction of energy with energy E

In a reversible reaction, a catalyst has no effect on the position of equilibrium. It simply speeds up the reaction so that equilibrium is reached faster and hence, the same equilibrium yield can be obtained more quickly. Both forward and backward reaction increases by the same amount. Hence, Kc value remain unchanged.

When a product of a chemical reaction acts as a catalyst in the reaction, the catalyst is said to be an autocatalyst. It is slow at first and then become more rapid as the catalyt is produced in the reaction.

In autocatalyst reaction, the concentration of the catalyst increases with time.

Eg. Reaction of acidified KMnO4
The smaller the size of the reacting particles, the greater the total surface area exposed for reaction and consequently the faster the reaction.
In homogeneous catalysis, both catalyst and reactant are in the same physical state.

The catalytic activity of a homogeneous catalyst depends on its ability to exist in variable oxidation states.

A homogeneous catalyst take part in the reaction and an increase in concentration will increase the speed of the rate-determining step.

Eg. Oxidation of S2O8 (2-), oxidation of atmospheric SO2 by atmospheric oxides of nitrogen, acid-catalysed esterification

In heterogeneous catalysis, both catalyst and reactant are in different physical states.

A heterogeneous catalyst works by providing a surface for which reactants are adsorbed and from which products of the reaction are desorbed.

Its catalystic activity depends on the availiability of partial filled 3d orbitals, which allows reactant molecules to be adsorbed onto the surfaces to be adsorbed onto the catalyst surface.

This adsorption weakens the bonds in the reactant molecules and hence, lowers the activation energy and increases the surface concentration of reactants. Reactant molecules are brought closer together and so, the rate of reaction is increased.

Eg. Haber process, Contact process, manufacture of margarine, catalytic removal of NOx in exhaust gases from car engines.

Enzymes are denatured by high temperature and extremes of pH. i.e the 3-D structure of enzyme is altered and its catalytic activity is destroyed.

Enzymeonly work well over a narrow range of pH about 5-8 and over a narrow range of temperature about 20-50 C

The rate of an enzyme-catalysed reaction increases at first, and then decreases as temperature increases as the enzyme starts to denature.

temperature
RateEnzymes are highly specified , catalyzing one particular type of reaction. A theory which accounts for their specificity is the lock and key model. According to the model, the substrate and the enzyme molecule have complementary shapes so that they fit together like a lock and a key. The substrate fit the active site of the enzyme in the same way that a key fits a lock, The bond –breaking and the bond-making processes that transform a substrate to products occur while the substrate is bound to active site of the enzyme. The enzyme-substrate complex breaks apart as the products are formed free to catalyse further reactions

In an enzyme- catalysed reaction,

1. Enzyme is very small compared to substrate
2. rate of reaction is directly proportional to enzyme.

For a fixed amount of enzyme, there is a finite number of active sites. Rate is directly proportional to substrate and the reaction is qpproximately 1st order w.r.t to substrate.

The increase in rate becomes increasingly smaller as increases.

Finally, increase in substrate has no effect at all on the rate of reaction; reaction is zero order w.r.t to the substrate.

At this point, the enzyme is saturated with its substrate. Each enzyme binding site has a substrate bound to it, and all the enzyme molecules are continuously catalyzing the conversion of substrate to product.

chemical equilibria ;

2009-04-08T20:25:00.002+08:00

Chemical Equilibria

(a)A reversible reaction is one which can proceed in both directions. Dynamic equilibrium refers to a reversible reaction in which the rates of forward and reverse reactions have become equal and there is no change in the concentration of the reactants and the products.

(b)Le Chatelier’s Principle states that if a change is made to a system in equilibrium, the system reacts in such a way as to tend to oppose the change and a new equilibrium is formed.

If the reactants added (or products are removed) in an equilibrium, a new equilibrium is produced which contains a higher proportion of the products, i.e. the position of the equilibrium shifts to the right.

If the pressure of an equilibrium mixture is increased, the mixture will try to reduce the pressure (Le Chatelier’s Principle) by reducing the number of moles of gas. Hence, a new equilibrium will be producing containing fewer moles of gas.

If the temperature is increased, the system tries to decrease it by ‘absorbing’ some of the extra heat energy and hence, favors endothermic reactions. If the temperature is decreased, the system tries to increase it by ‘producing’ heat and hence favors exothermic reactions.

(c)Equilibrium constants are only affected by changes in temperature only.
Equilibrium constants are not affected by changes in concentration, pressure or the presence of a catalyst for a reaction.

(d) and (e)
KC = { [C]c [D]d} / { [A]a [B]b}
Kp={ (Pc )cX (Pd)d} / { (PA )aX (Pb)b}
(f) and (g)In the chemical industry, the chemist aims to convert the reactants into products as quickly as possible, as completely as possible and as cheap as possible.
Thus, they would try to fufil the conditions:
1. Moderate temperature of 500℃ as forward reaction is exothermic.
2. Low pressure of 200 atm as the forward reaction is accompanied by a reduction in number of molecules of gases.
3. Use of a suitable catalyst to speed up both rates of forward and backward reactions to speed up the attainment of equilibrium.
The industrial conditions are:
i. Low temperature through increases equilibrium concentration of ammonia cannot be used as then rate of reaction will be too slow to be acceptable; rate of reaction is almost zero at room temperature. A temperature in the range of 450 to 500 degree Celsius is used in order to have a reasonable rate of reaction.

ii. High pressure favours both the rate of reaction and position of equilibrium. However, with increasing pressure, cost of an industrial plant and maintenance of the plant becomes more expensive. In reality,a pressure of 200 – 300 atm is used.

iii. To speed up the reaction to a reasonable rate, a catalyst of finely divided iron with promoter Al2O3 is used.

The yield of ammonia would be 10-15%.

chemical energetics ;

2009-04-08T20:21:00.001+08:00

Chemical Energetics

Chemical reactions are accompanied by heat energy changes.

a) Exothermic reactions
It is a reaction where heat energy is given out and temperature of reaction mixture rises.
Products have a lower energy level than reactants.
ΔH has a negative value.

Endothermic reactions
It is a reaction where heat energy is absorb from surroundings and temperature of reaction mixture drops.
Products have a higher energy level than reactants.
ΔH has a positive value.

bi) Enthalpy change of reaction
Enthalpy change of any given reaction, ΔH, however, can be obtain as follows after the reaction has taken place:
ΔH = (Total enthalpy of products) – (Total enthalpy of reactants)
Standard enthalpy changes
It refers to a reaction that is performed under the following conditions.
- A pressure of 1atm or 101 KPa
- Temperature of 298K (25 Degree Celsius )
- Substances must be in the physical state (solids, liquid or gas) that are normal under these conditions eg. Carbon dioxide is a gas/ substances in their most stable states eg. Carbon as graphite and not diamond
- Solutions, if any, at a concentration of 1mol dm¯³

Types of standard enthalpy changes

Standard Enthalpy change of formation ΔHf.
It is the enthalpy change of 1 mole of a compound is formed from its elements under standard condition, both compounds and elements are in their standard states
Eg. H₂ (g) + O₂ (g) → H₂O₂ (l) ΔHf = -188kJ

Standard enthalpy change of combustion ΔHc

It is the enthalpy change when 1 mole of a substance is completely burned in oxygen under standard condition
- Eg. C₂H₆+⁷⁄₂O₂(g) → 2CO₂(g) + 3H₂O(l) ΔHc= -1560kJmol¯¹

Enthalpy change of hydration
It is the enthalpy change for the production of a soluition of ions from 1 mole of gaseous ions. It is affected by ionic size and ionic charge.
Eg. Na⁺ (g) + aq → Na⁺ (aq) ΔH = -390kJmol¯¹

Enthalpy change of solution
It is the enthalpy change when 1 mole of solute is completely dissolved in a solvent to form an infinitely dilute solution under standard conditions of 1atm and 298K

Enthalpy change neutralizationEnthalpy change when one mole of water is formed during neutralization between an acid and a base under standard conditions of 1 atm and 298KEnthalpy change Atomisation
Enthalpy change when one mole of separate gaseous atoms are produced from the element in its standard state under standard conditions of 1 atm and 298Kb(ii) Bond Dissociation Energy, B.E.
Energy required to break one mole of covalent bonds between 2 atoms in the gaseous state.The greater the bond energy, the stronger the bond.

b(iii) Lattice energy Enthalpy change when 1 mole of an ionic compound is formed from its gaseous ions under standard conditions of 1 atm and 298K.

c) Heat is always transferred form a hot substance to a cold substance. This will produce a change in temperature, which can be measured. The amount of heat transferred from a hot substance to a cold substance can be measured if the mass of the substance, its specific heat capacity and the temperature change are known.Q= mc T the amount of heat transferred is generated by chemical reaction with a fixed molar quantity.
Hence the enthalpy change can be calculated as such:H = Q / No. of mol of limiting reagent x coefficient of limiting reagent.

E.g. In an experiment, 10g of gallium metal (in excess) was added to 250 cm3 of 0.2 mol dm-3 CuSO4 in a plastic cup. The temperature of the solution is increased by 14.2°C when the reaction was completed. The Equation for the reaction is

2Ga(s) + 3Cu2+(aq) à 2Ga3+(aq) 3Cu(s)

Calculate the enthalpy change of reaction.Q= mc T
= (250 x1.00) x 4.20 x 14.2
= 14910J
No of mol of CuSO4 = 250/100 x 0.2 = 0.05 à limiting reagentHence, 14.91 kJ of heat energy is evolved when 0.05 mol of CuSO4 reacts with GaQ = 14.91 x 3/0.05 =894.6 kJ

Hrxn = -894.6 kJ mol-1
d) Ionic radius:With reference to the lattice energy for NaF, NaCl, NaBr and NaI
è lattice energy becomes smaller in magnitude as the size of ions increases.
- The smaller the size of ions, the closer they can approach each other in the soild crystal, i.e. the shorter the interionic distance between the ions.
- Thus, electrostatic attraction is stronger
- Hence, lattice energy increases.
Ionic charge:
With reference to the lattice energy of NaCl and MgCl2,
è lattice energy becomes larger in magnitude as the charge of ions increases.
- The greater the ionic charge, the stronger the attraction between ions.
- Hence, lattice energy increases.

gaseous state ;

2009-04-08T20:10:00.002+08:00

The Gaseous State

(a) Basic assumption of kinetic theory as applied to ideal gas.

1. Gas particles have negligible volume when compared with the volume of the whole gas.
2. Gas particles have no intermolecular forces of attraction, except at the instant of collisions.
3. Gas particles in constant random motion.
4. Collisions between molecules are perfectly elastic.

(b) (i) Conditions necessary for a gas to approach ideal behaviour.

1. Molecular size
- Molecules of a gas have finite volume and not negligible volume.
- Measured volume appeared to be larger than ideal.
- The larger the size of the molecules, the greater the deviation from ideality.

2. Intermolecular forces
- Interactive forces between the molecules cannot be neglected.
- Attraction tends to make the observed gas volume smaller than ideal.
- Observed pressure is also less than ideal as molecules near the wall experience an overall force pulling back into the bulk.
- The stronger the forces between the molecules the greater the deviation.

(ii) High pressure

- Gas particles take up a larger percentage if total volume. i.e. volume of gas particles is significant due to the decrease in the volume of the gas.

- Gas particles are packed closer together, therefore intermolecular forces more significant.

Low temperature

- Gas particles have smaller kinetic energy and move closer i.e.

- Volume of gas particles is significant compared to volume of gas which is now smaller.

- Intermolecular forces of attractions between gas particles are more significant.

General Gas Equation

pV = nRT where p = pressure in Pa
V = volume in m³ n = no. of moles in gas
R = gas constant (8.31 JK-1mol-¹)
T = temperature in K

~ To find the determination of Mr, substitute the no. of moles (n) to (mass / Mr) and sub values given in the question into the equation respectively.

atomic structure ;

2009-04-08T20:05:00.001+08:00

Atomic Structure

Particle
Protons,Neutrons and Electrons

Symbol
p,n,e

Relative Electric Charge
+1,0,-1

Relative Mass Location
Nucleus,Nucleus & surrounding the nucleus

Isotopes
Definition: Isotopes are atoms of the same element with different number of neutrons but same number of protons.

Have the same…
i. Atomic number or proton number
ii. Number of electrons
iii. Electronic Configuration
iv. Chemical properties

Have different…
i. Number of neutrons
ii. Mass numbers
iii. Relative isotopic mass
iv. Physical properties

Orbitals
Definition: Orbitals are regions in space in which there is a greatest probability of finding a particular electron.

Shapes of Orbitals
(1) s orbital
- each s sub-shell has 1 orbital only
- spherical shape
- size increases as the principal quantum number increases.
(2) p orbital
- each p orbital has 3 orbitals
- dumb-bell shape
- different axes of symmetry for each p orbital
(3) d orbital
- each d orbital has 5 orbitals
- orbitals with the same principal quantum number have the same energy i.e they are degenerate.

Relative energies of sub-shells
The energy level of a particular principal quantum shell is s <>

Aufbau Principle: Electrons occupy orbitals of the lowest energy available.

Pauli Exclusion: Each orbital can accommodate only 2 electrons, and these must have opposite spins.

Hund’s Rule: When electrons are added successively to a sub-shell, they occupy the orbitals singly first before pairing occurs. All electrons in singly occupied orbitals have the same spin.

Ionisation Energy
Definition: Ionisation energy is the minimum energy required to remove one mole of electrons from one of gaseous atoms/ions to form one mole of gaseous cations.

Factors affecting ionization energy
Nuclear Charge [No. of protons]
Size of atom
Screening or shielding effect
Charge
Orbital penetration
Electron pairing

Trend of ionization energy
v Ionisation energy increases across a period.
v Ionisation energy decreases down a group.

Atomic Structure

(a) Protons are positively charged. Each proton has a relative charge of +1 and a relative mass of 1 atomic mass unit

Neutrons are uncharged. Each neutron has a relative charge of 0 and a relative mass of 1 atomic mass unit

Electrons are negatively charged. Each electron has a relative charge of -1 and a relative mass of 1/1840 atomic mass unit

(b) Protons and electrons are deflected by both electric and magnetic fields, but in opposite directions
- Protons are deflected towards the negative potential
- Electrons are deflected towards the positive potential
- Neutrons are not deflected at all
The size of the deflection depends on the relative masses of the particles. The lighter particles are deflected more than the heavier ones.

Electrons are lighter than protons, so, are deflected more than protons.

(c) In an atom, the protons and neutrons are tightly packed in the nucleus, thereby making the nucleus very dense.
- The nucleus provides nearly all the mass, but very little of the volume of an
atom. Most of the rest of the atom is empty space, where the electrons move.
- The nucleus is exceeding small compared to the size of the atom itself. The
diameter of an atom is typically in the order of 105 times the diameter of its
nucleus
- The electrons are attracted electrostatically by the positively charged protons

In an atom, the number of electrons is equal to the number of protons. i.e. atoms are electrically neutral

(d) Number of electrons = Number of protons
Number of neutrons = Nucleon number – proton number

In a negative ion, the number of electrons is greater than the number of protons since a negative ion is formed by adding electrons to a neutral atom

In an positive ion, the number of electrons is less than the number of protons since a positive ion, is formed by removing electrons from a neutral atom

(e) Isotopes are atoms of the same element that have the same proton number but different number of neutrons

Isotopes therefore distinguished based on the different number of neutrons

Isotopes have the same chemical properties, but different physical properties

(f) A sub shell is a group of orbitals with the same energy level, but differ in their orientation in space

In an atom, the orbitals have definite amounts of energy called energy levels.

In an atom, the orbitals are filled in order of increasing energy
- Aufbau Priniciple – The added electron will always occupy the orbital with the lowest energy first

- Pauli Exclusion Prinicipal – each orbital can hold a maximum of 2 electrons of opposite spins

- Hund’s Rule of Multiplicity – When filling a sub- shell, each orbital must be occupied singly (keeping electron spins the same before they occupied in spins)

Paired electrons can only be stable when they spin in opposite directions so that the magnetic attraction which results from their opposite spins can counterbalance the electrical repulsion which results from their identical charges

(g) s orbitals are spherical
p orbitals are dumb bell shaped

(h) The electronic configuration of an element describes how the electrons of its atoms are arranged in their shells, sub shells and orbitals

(i) The first ionization energy of an element is defined as the amount of energy required to remove one electron from each atom in a mole of gaseous atoms producing one mole of gaseous cations

Size of the positive nuclear charge:
As the nuclear charge increases, its attraction for the outermost electron increases and more energy is required to remove an electron, i.e. ionization energy increases

Size of atom/ion
As atomic/ionic size increases, the attraction of the positive nucleus for the negative electron decreases and less energy is required to remove an electron, i.e. ionization energy decreases

Screening effect of inner electrons
The outermost electron is screened (shielded) from the attraction of the nucleus by the repelling effect of the inner electrons. As shielding increases, the attraction of the positive nucleus for the negative electron decreases and less energy is required to remove an electron, i.e. ionization energy decreases

(ii) Ionization energy decreases down a group (in spite of the higher charge on the nucleus) due to increasing atomic size and increasing shielding effect

Down a group, the atomic radius increases due to the increasing number of shells of electrons

The outer electrons are therefore, further from the nucleus and are better shielded by the inner shell of electrons. They become less strongly attracted by the positive nucleus and so, less energy is required to remove the electron

Ionization energy increases across a period due to increasing nuclear charge and decreasing atomic radius

Since all the electrons all go into the same shell, the shielding of the ionizing electron is about the same. The outer electrons are, therefore, increasingly more strongly attracted by the positive nucleus and so, more energy is required to remove an electron

atoms molecules and stoichiometry ;

2009-04-08T19:58:00.001+08:00

Atoms, Molecules and Stoichiometry

Learning Outcomes

a) Define the terms relative atomic, isotopic, molecular and formula masses, based on the ¹²C scale.

· Relative atomic mass (Ar) is defined as the mass of one atom of an element compared with 1/12 the mass of one atom of carbon- 12. No unit.

· Relative isotopic mass is defined as the mass of one atom of an isotope compared with 1/12 the mass of one atom of carbon- 12 (i.e. ¹²C). No unit.

· Relative molecular mass (Mr) of a compound is the sum of the relative atomic masses of all the atoms in one molecule of a covalent compound. No unit.

· Relative formula mass is the sum of all relative atomic masses from the formula of any give substance (atoms, molecules, ions, ionic compounds, etc). No unit.

b) Define the term mole in terms of the Avogadro constant.

· The number of carbon atoms present in exactly 12.0g of carbon- 12 is 6.02 x 10²³. This huge number is known as the Avogadro constant.

· Hence, one mole of any substance is the amount of substance containing 6.02 x 10²³ particles.

d) Define the terms empirical and molecular formulae.

· An empirical formula shows the simplest whole-number ratio for the atoms of different elements in a compound.

· A molecular formula shows the actual number of atoms of the different elements in one molecule of a compound.

f) Write and/or construct balanced equations.

· Examples:

1) 2Na (s) + 2HCl (aq) → 2NaCl (aq) + H2 (g)

2) C7H6O3 + CH3OH → C8H8O3 + H2O

3) Zn (s) + 2HCl (aq) → ZnCl2 (aq) + H2

bdae treat from Hong ;

2009-03-29T20:16:00.009+08:00

depression ;

2009-03-25T00:09:00.004+08:00

DEPRESSION

Depression is when yoo can't sleep & yoo get so bored looking at your roof, that yoo spend weeks nights contemplating what to do with it only to find that yoo wouldn't have enough determination to do it.

Depression isn't always suicide.

Depression is ovbious to only yourself. Suicide is ovbious to everyone.

Depression is, & always will be, my, and many others, mays of life.

Depression runs my life, makes me do things ii shouldn't do.

Depression is that voice in the back of your head telling yoo, that yoo need help.

Depression makes yoo gain weight, loose weight, not eat, eat too much, do drugs, give or take a few.

Depression has the feeling of death, without the dying part.

Depression is still killing yoo even if yoo have the best things in the world.

Depression isn't just having too little, it's having too much as well.

Depression is never seeing your father happy.

Depression is loosing your brother to his girlfriend.

Depression is the killing of the broken pieces of your heart.

Depression is slow motion and fast motion at the same time.

Depression is the illusion that the world has turned it's back on yoo & everyone in it.

Depression is seeing happiness everywhere yoo go.

Depression is hoping to survive and hoping not to at the same time.

Depression isn't contemplating suicide, but wishing yoo were already there.

Depression is when the only thing that cares is the depression itself.

Depression is when yoo are at school and yoo can't remember things yoo learnt in grade 5.

Depression is falling alseep in your favourite subject.

Depression is hating yourself because your parents hate yoo.

Depression is the hatred of your family.

Depression eats your insides with a smile on it's face.

Depression is the look in your eyes when yoo wake up in the morning, knowing yoo have to live another day.

Depression is yourself, yoo are depression.

Depression makes yoo who yoo are and who yoo'll always never want to be.

Depression makes yoo miss your old self, but once your better, yoo miss depression. but for me, mostly, depression is all of these, plus, depression is when yoo have had it so long that yoo are scared of who yoo will be when and if yoo get better. yoo wonder if yoo could survive happy and if the happiness would eat yoo. now ask yourself.. do yoo have depression?

my bdae treat ;

2009-03-20T15:47:00.009+08:00

bdae ;

2009-03-20T15:25:00.005+08:00

This is where ii had my first birthday meal from EngJia. This is just the Hotel name. we only hab Swensen inside. ! peeps, dun think wild! wahahaha. (:

EngJia's Sirloin Steak & my Salmon 'N' Mushroom Pasta.

hold me close ;

2009-03-03T23:02:00.001+08:00

[出路]

走出去就有路

寻见了就有福

拥有了一切

都进了包袱

思念是带不走的

天空疑云密布

心中翻腾起伏

虽将飘摇

前途仍模糊

此地会是我

衣锦还乡处

* 飘洋过海

我吃得起苦

相信天无绝人之路

现实有咒诅

梦里有祝福

有缘同舟风雨同渡

顶着烈日当空

眼底有迷雾

不能再让懦弱困住

日子多坎坷

命运有变数

只盼久旱逢甘露

走出去就有路

寻见了就有福

拥有了一切

都进了包袱

思念是带不走的

天空疑云密布

心中翻腾起伏

虽将飘摇前途仍模糊

此地会是我

衣锦还乡处

* 飘洋过海

我吃得起苦

相信天无绝人之路

现实有咒诅

梦里有祝福

有缘同舟风雨同渡

顶着烈日当空

眼底有迷雾

不能再让懦弱困住

日子多坎坷命运有变数

只盼久旱逢甘露

* 飘洋过海我吃得起苦

相信天无绝人之路

现实有咒诅梦里有祝福

有缘同舟风雨同渡

顶着烈日当空眼底有迷雾

不能再让懦弱困住

日子多坎坷命运有变数

只盼久旱逢甘露

awaiiting.

2009-03-03T19:39:00.003+08:00

the pain that pierce truu my heart ;

2009-02-10T01:19:00.000+08:00

Darkness
by Emily
I'm swimming all alone in a pool of darkness

and I feel like darkness is slowly pulling me under

I yell for help but no one is there to hear it

I begin to see the water at eye level

and I kick and flail

fighting to stay above the darkness

But the darkness won't let go of its hold on me

and I slowly begin to give into the feeling that lies below the water line

the waters starts to fill my lungs

the lungs that once held so much life

yet now they allow the murky water to replace that

I know that this path doesn't lead to happiness

But why doesn't someone grab my hand

pull me from darkness's grasp?

Because no one knows I stand at the boundary

The boundary between light and dark

so I give in to the thing that holds me

All of the strength and all of the courage that I once held in my heart can't save me from the water

So I slowly slip below the world of conscientiousness

undetected by the occupants of that world

I don't want to fight anymore

I've given into darkness

awaiiting.

2009-02-09T18:04:00.001+08:00

郭静-下一个天亮

用起伏的背影

挡住哭泣的心

有些故事不必说给每个人听

许多眼睛看的太浅太近

错过我没被看见那个自己

用简单的言语

解开超载的心

有些情绪是该说给懂的人听

你的热泪比我激动怜惜

我发誓要更努力

更有勇气

* 等下一个天亮

去上次牵手赏花那里散步好吗

有些积雪会自己融化

你的肩膀是我豁达的天堂

* 等下一个天亮

把偷拍我看海的照片送我好吗

我喜欢我飞舞的头发

和飘着雨还是眺望的眼光

用简单的言语

解开超载的心

有些情绪是该说给懂的人听

你的热泪比我激动怜惜

我发誓要更努力更有勇气

* 等下一个天亮去

上次牵手赏花那里散步好吗

有些积雪会自己融化

你的肩膀是我豁达的天堂

* 等下一个天亮

把偷拍我看海的照片送我好吗

我喜欢我飞舞的头发和飘着雨还是眺望的眼光

# 时间可以磨去我的棱角

有些坚持却永远磨不掉

请容许我小小的骄傲

因为有你这样的依靠

* 等下一个天亮

去上次牵手赏花那里散步好吗

有些积雪会自己融化

你的肩膀是我豁达的天堂

* 等下一个天亮

把偷拍我看海的照片送我好吗

我喜欢我飞舞的头发

和飘着雨还是眺望的眼光

awaiiting.

2009-02-01T20:29:00.002+08:00

曾咏霖-自己的梦

萤火虫的梦

谁没有梦

谁不曾感动

天空是雨是风

还是絢烂彩虹

你们教我学会从容

时间的钟

分分钟在跳动

快乐还有伤痛

我知道你都懂

你们的笑容

溶化所有泪水的沉重

# 拥抱每一个梦

总有颗星会为我闪动

困难再大我都会去碰

相信下一秒会变不同

编织每一个梦

总有些风会为我吹送

前路崎岖我不会放松

你们给的珍重

一直在心中

Repeat #

awaiiting.

2009-01-18T16:25:00.003+08:00

tryiny to forget someone yoo love is like trying to remember
someone yoo neber know.
yoo know yoo really love someone when they are the last one
yoo think about and the first thing yoo think about every
morning.
People say that if yoo truly love someone, yoo should let them go but if yoo let them go.
What makes yoo think that they will come back?

my love ;

2009-01-17T17:03:00.003+08:00

\\ It stalks da dae,
// It seeks out life,
\\ And whisks it awae.
// It's known as Death
\\ And othEr thinqs tOo.
// But it's all da same
\\ Watt matters is yoo.
// How dO yoO see it?
\\ Watt dOes it mean?
// It's best if yoO nOe.
\\ For Death is unseen.
// It can take yOo at dae,
\\ It can take yOo at niqht,
// Knowinq Death well.
\\ Can lend yOo some liqht,
// The passaqe tO Death
\\ Is owaes unclear.
// And it's best tO nOe
\\ That yOo're verii near .
// For Death is at hand
\\ It is for us all.
// Know it's face well
\\ So yoO don't stumble & fall.
// Now think hard on Death
\\ And know that it's near,
// And the meaninqq of life.
\\ Will be all to clear
// And that is to live,
\\ For your hearts desire.
// Not tO stumble Or fall
\\ But tO burn with a fire.
// A fire for life
\\ To live for each dae.
// To reach for your dreams
\\ No matter what people say.
// Life is a question
\\ And death holds a clue.
// Reach not for the answer,
\\ For your life's not due
// Live for the moment
\\ And die for it too.
// For it's the moment that counts,
\\ It, and you.
// Now I'm all dOne,
\\ I've said watt I'll sae.
// Just remember one thinqq,
\\ Live fOr the dae .

// death awaiits yoo .

forever my love ;

2009-01-13T21:08:00.002+08:00

当我们同在一起

如果云是天空的呼吸　
风是我慌张的叹息
回忆是爱的延续
只因为你和我已经不再一起

当我们同在一起　在一起　在一起

空气里有午后的暖意　
我听着沙沙收音机
突然间　
下起了雨　
雨让我好想好想你　想抱着你

当我们同在一起　在一起　在一起
在一起　在一起　齐快乐无比

＊你是我曾经的甜蜜
我是你爱情的过去
那一段美好的记忆　我们都不能够忘记
因为我很爱很爱你　
所以能微笑着离去
虽然我不会再见你
幸福是我们曾经在一起

Repeat ＊

空气里有午后的暖意　
我听着沙沙收音机
唱什么　听不清晰　
因为我傻傻的笑着　想起了你

当我们同在一起　在一起　在一起　在一起　在一起

When we were together

If cloud is the sky’s breath
Then Wind is my flustered sigh
Memory is love’s continuation
It’s only because yoo and I are no longer together

When we were together, together, together

There is warmth in the afternoon air
As I listen to the cracking radio
Suddenly [I feel like there’s] a gap
The rain lets me think of yoo very much, think of hugging yoo
Rain has fallen

When we were together, together, together
Together, together, such an incomparable even happiness

* You are my past sweetheart
I am your past lover
That one part of a great memory, we all can’t forget
Because I really, really love yoo
Therefore I was able to smile as I walked away
Although I can no longer see yoo again
Happiness is [knowing the fact that] we were together once

There is warmth in the afternoon air
As I listen to the cracking radio
What is playing? [i] Couldn’t listen clearly
Because I am smiling silly [as] I am thinking of yoo

When we were together, together, together,
together, together

take my hands & we shall neber part ;

2009-01-09T18:41:00.001+08:00

death awaiits yoo ;

2009-01-04T22:13:00.001+08:00

I get a funny feeling.

It comes from deep inside.

I get all mad and angry,

wanting to go and hide.

My doctor calls it depression.

My dad says it's just me.

But the thoughts and feelings,

no one will ever be able to see.

Some say I'm psycho,

some say I'm just weird.

It's like I'm a different person,

and the old me just disappeared.

I get really edgy,

I wanted to commit suicide.

Then I get a headache,

followed by feeling sad.

I wish I could get help,

I wish it would go away.

Maybe if I keep praying real hard,

It will be far away.