FANCY THAT (V) : CORRECTION FLUID

CORRECTION FLUID

Correction fluids normally contain trichloroethane.

This is very volatile ( easily changes to a vapour ).

When exposed to the air, this liquid in the correction fluid evaporates leaving the familiar white solid.

FANCY THAT (IV) : ANAESTHETIC

ANAESTHETICS

There are chemicals with sleep-inducing properties. One of the first to be used was ether, C2H5OC2H5, in 1846.

Prior to that date, surgery was a very risky and painful experience. The surgeon had to be very quick in doing the operation and often the patient died from shock!

Laughing gas, nitrogen (I) oxide, N2O was another early anaesthetic, but perhaps the well known of all was chlorofoam, CHCl3. This was first used by Sir James Simpson in 1847.

He used it on women at childbirth. This met with great opposition from various religious groups. However, in 1853, Queen Victoria used it at the birth of Prince Leopold. Since then there has been little religious objection!

Nowadays, other halogenated hydrocarbons are used. Chlorofoam itself is too toxic. Ether is too flammable and dangerous, while laughing gas does not produce a deep sleep.
More substituted hydrocarbons become more inflammable and have more anaesthetic effect. However, the disadvantage is more toxic.

The solution is to use a halogenated ethane molecule!
The most common anaesthetic in operation theatres is
1,1,1-trifluoro-2-chloro-2-bromoethane.

It is more commonly known as fluoethane.

FANCY THAT (III): DECLINE AND DOWNFALL OF ROMAN EMPIRE

'DECLINE AND FALL OF ROMAN EMPIRE’?

In Roman times, the metal lead was common.

It was called plumbum and was used for making containers, various cooking implements and water pipes.

They also store their wine in lead vats and even added it to some wines to improve their flavour!

Lead is poisonous and perhaps, one of the reasons for the ‘decline and downfall’ of the Roman Empire was lead poisoning!

FANCY THAT (II): COSMETICS

COSMETICS

Chemicals which are used for improving the appearance or for beautifying are called cosmetics.
Since very early times, people have been concerned with their appearance and had sought the help of chemicals.

Egyptians, in 5000 B.C., used a fine powder formed of Antimony (Sb), mixed with green copper (II) carbonate (CuCO3) and used as eye-shadow.

In Elizabethan times, iron (II) oxide (Fe2O3) rouge was used to give the face a rugged complexion.

However, in Georgian times, ‘pale faces’ were more in fashion and women used white lead carbonate (PbCO3). As a result many women died as a result of the poisonous nature of lead!

Nowadays, the manufacture of cosmetics is an important industry. Some of these simple salts are used in the cosmetics. Oils and creams are often natural hydrocarbons like carnauba (‘Brazilian Wax’) and paraffin waxes.

FANCY THAT (I) : The HOPE DIAMOND

The ‘HOPE’ Diamond

Diamond is a form of carbon where atoms are held together by covalent bonds in tetrahedral lattice. Each diamond crystal is in fact just one molecule made up of millions of covalently linked carbon atoms.

The ‘HOPE’ Diamond is perhaps the most famous or ‘infamous’ of all diamonds. It weighs 20g and was first used to form the eye of a statue of Sita who was a Hindu goddess. Although its history is varied it hardly brought ‘hope’ to its owners. The story goes that when it was stolen from the statute, the goddess was very angry and made a curse on anybody who owned it.
After being stolen, it was taken to France. Eventually, some hundreds years later, it became part of the French Crown Jewels.

(1) Marie Antionette was believed to have worn the
diamond just before she was executed.

It was then sold to various owners all whom suffered ill luck.

(2) Its English owner, Henry Hope, from whom it got
its name, became bankrupt and died in poverty.

(3) Its Greek owner was killed in a car crash.

(4) A Turkish sultan was overthrown just after he had
acquired it.

(5) American owner, Mrs Evelyn Walsh tragically lost
all of her children in various accidents.

After her death, it was given to the Smithsonian Institute in Washington where it is currently on view.

FANCY THAT !

I came across my secondary school textbook ( from the midst of cobwebs ) with many interesting background reading and fascinating facts!

Some of the background reading are historical while others emphasize the importance of chemicals in modern everyday life.

Hence, i decided to add these into the blog entries so that you will find Chemistry not so CHE-MISERY , CHE-MYSTERY but CHE-MASTERY.

Note:

(1)These articles are adapted from COMPREHENSIVE CHEMISTRY FOR 'O' LEVEL SCIENCE by CHRISTOPHER N PRESCOTT.

(2) These articles are meant for sharing and not meant for any profit-making uses.

Ionic and Covalent Project for 3e1/2 sci chemistry

dear 3e1/2,

these are the compounds that you will have to make during the march holidays!

instructions:
(a) each pupil is to construct your own compounds. No group work. In short, you are responsible for your compounds.

(b) you may want to buy the styrofoam balls together as the shops don't sell one or two. This can help you to save cost.

(c) for large structure, please limit the structure to be 15 cm by 15 cm. This means you don't need so many styrofoam balls. The structure will be small and cute, right?!

(d) just make 1 will do. Don't make extra!

(e) the number refers to the number you have chosen! Eg: (41) diamond meant the person who chose 41 will have to make DIAMOND.

(f) different elements are represented by diffeent colours. Eg: chlorine is green.
please use the appropriate colour.

here are the compounds you have to make:

1. carbon dioxide ( number 1 and 20 )
2. methane ( number 2 and 21 )
3. chlorofoam
4. ethanoic acid ( vinegar )
5. ethanol
6. hydrogen chloride ( number 6 and 22 )
7. hydrogen molecule ( number 7 and 23 )
8. fluorine molecule ( number 8 and 24 )
9. chlorine molecule
10. sodium chloride ( 15 cm by 15 cm ) ( number 10 and 27 )
11. ammonia molecule
12. hydrogen fluoride ( number 12 and 28 )
13. oxygen molecule ( number 13 and 25 )
14. nitrogen molecule ( number 14 and 26 )
15. silicon dioxide ( 15 cm by 15 cm )
16. sodium fluoride ( 15 cm by 15 cm )
17. carbon monoxide
18. sulfur dioxide
19. nitrogen dioxide

and 29. water molecule

that's all, enjoy folks!

this project is for pupils in miss pang's group. Have fun and enjoy!

Explanation For Electrolysis- FYS Pg (4)1-(4)17

Multiple-Choice Question

(2) C
reason: filtration, crystalization and distillation are physical methods. Can only separate mixtures not the individual elements within a compound.

(3) D

reason: elimination method: Aq NaCl and Molten NaCl will have products at electrodes. Bromine is a poor conductor of electricity. Mercury is a metal, just that it exisit in liquid state and it can conduct electricity. So, of course it can conduct electricity. Actually, this question can be seen as a electricity question.

(4) C

reason: cations are attracted to cathode: only option C is cation.

(5) D

reason: this is a typical example of electro-plating, Remeber i taught you to draw cathode on the left? For electro-plating, the object to be plated is on the cathode ( the negative electrode ) while the metal is on the anode ( positive electrode ). Obviously, the electrolyte must be the salt solution of the metal used for plating.

(6) D

reason: the question is trying to ask you what are the possible ions for conc LiCl. So there should be Li+, Cl- (from salt) and H+, OH- ( from water). Cations move towards cathode and anions move towards anode.

BUT, if the question asked about products, then LITHIUM is not discharged. Instead Hydrogen gas. Reason: Lithium is high up in the electro-chemical series as compared to hydrogen!

(7) C

reason: anions attracted to anode. So, no need to crack your brains thinking about the options. All the rest of the options are cations!

(8) B

reason: From the products, X and Y2, you can deduced it is a compound with the formula XY2.

(9)D

reason: Firstly, you need to choose 2 different metals from the reactivity series. And the electrolyte need to be aqueous ( ions ) or molten. But, Cu and Ag is quite a poor example. Why? Because these metals are not much further apart in the reactivity series. The voltage produced will not be larger enough.

(10) B

reason: ions discharged: H+ and Cl-. H+ discharge because Na+ is more difficult to be discharged due to electro-chemical series. Cl- is discharged due to 'concentration effect', so OH- ( from water ) is not discharged instead.

(11) D

reason: cathode gains mass due to copper from anode deposited onto it. Option C is rejected because electrode has weight, should not start from zero.

(12) B

reason: metal ions gain electrons at cathode while non-metal lose electrons at anode.

(13) A

reason: in aqueous copper (II) sulphate. Copper is below hydrogen in the electro-chemical series. So, copper ions will be discharged and copper will be deposited on to the cathode.

(14) B

reason: choose 2 different metals from the reactivity series. Question request for the greatest voltage.

(15) A

reason: (B)-anode is chlorine ( if concentrated; else is O2 ); cathode is hydrogen- NEVER sodium

(C):anode-hydrogen, cathode-sodium

(D):anode- bromine, cathode-lead

(16) A

reason: notice electrode X is connected to positive terminal, so electrode X is anode. Anions are attraced to anode. Cl- ions becomes Cl2 gas. Oxidised.

(17) A

reason: tricky question: the electrode is CARBON. this means all the ions involved are from the ELECTROLYTE. Cu2+ are attraced to cathode while OH- are attraced to anode. So, more of H+ is left behind. Hence solution becomes more acidic. If the question changes to COPPER electrode, then the concentration of CuSO4 and colour remains unchanged!

(18) C

reason: anions attracted to anode. SO42- is not discharged and OH- is discharged instead. This is the concept of 'Selective Discharge'.

(19) A

reason: (B) solution will become acidic. see question 17. For option C, Cl- will be discharged at the anode, H+ will be discharged at the cathode. So, the solution will have more OH- remaining. Hence, it will be alkaline. Option (D): due to the removal of water molecules [ cathode: hydrogen, anode: O2 ], so the concentration of sulfuric acid increases.

(20) B

reason: (A):how can cation forms negative ions. (D):R is below hydrogen, because if it is aqueous, then metal R ions will not be discharged.

(21) A

reason: electrons flow from anode (+) to cathode (-). so, cathode should be Y. Cathode is the more reactive metal.

(22) A

reason: for concentrated or dilute, sodium is NEVER discharged.

(23) C

reason: just focus at cathode-metal; anode-non metal. For option (A), it should be metal ions gaining electrons, and not giving electrons.

(24) B

reason: anode dissolves, all the Cu2+ ions are attracted to cathode hence metal is deposited. electrolyte remains unchanged. IF the electrode is NOT COPPER, example: carbon, then the blue colour of CuSO4 will fade away.

(25) B

'that's all folks!'

ELECTROLYSIS

Molten

Ions attracted to the cathode: Only positive ions ( metal ions )

Ions attracted to the anode: Only negative ions ( non- metal ions )

Cathode: Metal
Anode: Non-metal

Aqueous

Ions attracted to the cathode: Only positive ions
( non-reactive metal ions and hydrogen ions )

Ions attracted to the anode: Only negative ions
( non-reactive metal ions and hydroxide ions
Cathode: Non-reactive metal or Hydrogen gas
Anode: Halogen ( for concentrated )or oxygen ( for dilute cases )

Aqueous ( concentrated / dilute )

Concentrated :
Cathode: non-reactive metal or hydrogen gas
Anode: halogen or oxygen gas.

Dilute
Cathode: non-reactive metal or hydrogen gas
Anode: oxygen gas

If the electrode is reactive, it often dissolves in electrolyte.

Electric Cell ( Simple Cell)

• The further apart the metals are in the reactivity series, the greater the voltage.
• The more reactive metal is placed at cathode. Eg: Zinc at cathode; Copper at anode.
• Any salt solution can be used at electrolyte.

Value Added Series I ( Preparation Of Salts )

Most pupil are puzzled regarding the use of various salt-making methods.

(1) why can't titration be used for all the salts?

(2) Since the first reaction for the topic 'Acids-Bases' introduced 'acids react with REACTIVE metals to give salt and hydrogen gas, can we use this method instead?

Discussion:

There are many methods to make a salt, HOWEVER, we need to see if the method is feasible ( workable).

For the case of 'reactive metals and acids'

Of course, you can use reactive metals and acids to make a salt.

BUT, it will be too dangerous if you are using a REACTIVE metal.

Eg: To make Potassium chloride (KCl), it will be DANGEROUS if you are going to react Potassium with Hydrochloric acid ! Potassium explodes with cold water. [Can You Imagine the reaction of potassium with acids?]

Hence, this method ( acids with reactive metals) can only be used for metals that are moderately reactive! example: magnesium, zinc, etc.

If you want to form Copper(II) sulphate, you cannot use this method because copper is unreactive to acids!
Hence reacting copper(II) oxide/carbonate with acids is the ONLY method!

_____________________________________________________

For the case of 'insoluble oxides/insoluble carbonates with acids'

Ever wonder why it has to be insoluble reagents in the first place?

Back to basics: 'what are acids made of' ?

'An acid is a substance that produces H+ ions when dissolve in water.'

In short, there is water in an acid.

If the oxides and carbonates are soluble in water, then how do you ensure that your acids will be FULLY reacted?

remember in our procedure for heating insoluble oxides/carbonate with acids, step #2

(1) Warm the acid.
(2) add EXCESS insoluble oxides and carbonate and stir to dissolve.
(3) FILTER the mixture ........

If your acids did not REACT with the insoluble oxides/carbonate FULLY, then the acid will contaminate the salt that is formed in the process!

In short, for the usage of heating acids with reactive metals/ insoluble oxide/ insoluble carbonates, the REASONS behind it include:

(1) the oxides /carbonates will be insoluble in water, hence will definitely be able to react with the acids FULLY. Upon complete reaction with acids, all excess metal/insoluble oxides/carbonates will remained and this is an indication that all acids had fully reacted.

(2) the metals used are moderatly reactive and is suitable to react with warm acids.

______________________________________________________

What about 'titration'?

There are a few reasons for the usuage of titration.

The first reason is because the metal is too reactive and using their hydroxides is more appropriate.

Eg: to make sodium nitrate. We cannot use sodium metal as it is far too reactive with acids.
So, we use sodium HYDROXIDE and nitric acid.

In this case, we cannot use heating method as both are soluble and we cannot tell when neutralization takes place.

Hence, for the second reason:

Second reason: If you use soluble oxides and carbonates for the method of heating, one problem you foresee would be unable to know when neutralization occurs. Reason: all the reagents are soluble, you can't tell. ( recall for the case of heating insoluble oxides/carbonates, the reagent is insoluble so you can see when the reagent no longer dissolves in the acid).

But titration is able to tell because of the use of INDICATOR.

Hence, we will be able to know the EXACT amount of alkali needed to neutralize the acid to form the salt when the indicator CHANGES COLOUR.

Please do not state this reason as your answer for 'why titration is used': 'because if we use insoluble oxides/carbonates, it will not be able to pass through the burette' !!!!

I mentioned this point to the class because i wanted you to remember insoluble hydroxides and oxides cannot be used for titration in the LABORATORY. How can an insoluble reagent flow through a burette?

The answer why 'titration is used instead of heating method' because: ** both the reagents are soluble and there is NO INDICATION when neutralization takes place. For titration, indicator can be used to identify the point of neutralization.

Now, is it much clearer?!

2007 EYE PURE CHEM PAPER SOLUTION

SECTION A (MCQ)

1. (B)

2. (C)

3. Redox not covered in sec 3, anyway, answer is (A)

4. (A)

5. given no. of moles of Al2O3 = 1.0 mole
mole ratio of Al2O3:O2 is 2:3
no. of moles of oxygen is 3/2 x 1 = 1.5 moles
mass = mole x Mr of (O2)
= 1.5 x 2(16)
= 48 g (B)

6. chlorine = 2,8,7
when chlorine gains 1 electron to form chloride ion, it becomes 2,8,8 and it has 3 SHELLS
fluorine = 2,7
when fluorine gains 1 electron to form fluoride ion, it becomes 2,8 and it has 2 SHELLS
Magnesium = 2,8,2
when magnesium lose 2 electrons to form magnesium ion, it becomes 2,8 and it has 2 SHELLS
Oxygen = 2,6
when oxygen gains 2 electrons to form oxide ion, it becomes 2,8 and it has 2 SHELLS

so form the largest radius.... which means greater 'circumference' = chlorine
(A)

7. chemical analysis not tested in sec 3, anyway, answer is (B)

8. for graphite, each carbon atom is COVALENT bonded to each other. However, the carbon atoms form a HEXAGON RING. Each ring is connected to another ring by weak VAN DER WAALS ( weak VDW) forces of attraction. Graphite is used as lubricant because its layers can SLIDE over each other. (D)

9. (D)
All these elements are from group 2. All have 2 electrons in the outermost shell.

10. (B)

11. REDOX not teated in sec 3, anyway, answer is (D)

12. option (A) look like group 1 metals , option (B) look like macromolecules. copper is a metal, so it will have HIGH MP, HIGH DENSITY, GOOD ELECTRICAL CONDUCTIVITY (D)

13. (B)

14. empirical formula is the SIMPLEST ratio but MOLECULAR FORMULA is the formula multiply by a factor. In order to calculate the Molecular Formula, we need the relative molecular masses. Eg: the Mr of methane, CH4 is 16 while the Mr of (CH4 )2 is 32. (B)

15. given conc of acid = 1.0 M and mass of CaCO3 = 1.0 g.

no. of moles of CaCO3 = 1/100 = 0.01 mol

mole ratio of HCl: CaCO3 is 2:1

no. of moles of HCl = 0.01 x 2 = 0.02

vol = 0.02 / 1.0 = 0.02 dm3 = 20 cm3 (B)

16. H2SO4 + MgO ---> MgSO4 + H2O ;

H2SO4 + MgCO3 ---> MgSO4 + H2O + CO2

so, in both reactions, water is formed. (C)

17. CHEMICAL ANALYSIS not tested in sec 3, anyway, the answer is (A)

18. (A)

19. option B is very interesting. Covalent compounds are made up by atoms.... but the BETTER word for ' Nature of Particles' should be MOLECULES. Anyway, the formula for option B is wrong too. answer(C)

20. you need knowledge from Chemical Analysis, not tested in sec 3. Anyway, option (D)

21. (C)

22. if X is noble gas, then X,Y,Z is consecutive. So, Y should be in group 1, Z should be group 2.(D)

23. IMPT

Cl2 (g) + 2KBr ( aq) ---> 2KCl (aq) + Br2 (aq) ; colour of KBr and KCl = colourless; but aqueous Br2 = reddish brown

Cl2 (g) + 2KI (aq) ---> 2KCl (aq) + I2 (aq) ; colour of KI and KCl = colourless; but aqueous iodine is dark purple or blue (D)

24. although both potassium (2,8,1) and calcium (2,8, 2) have more electrons than aluminium ( 2,8,3 ). But aluminium donates MORE electrons into the sea : Al (s) ---> Al3+ (aq) + 3e- so answer (A)

25. total no. of electrons share = no. of BONDS in the molecule: 8 bonds x 2 e- = 16 e- answer (C)

26. (C) reason: the formula should be XO

27. when ammnium chloride is heated, it forms ammonia gas and hydrogen chloride gas: NH4Cl (s) ---> NH3 (g) + HCl (g) option (B)

28. notice the no. of protons and elecytrons for both X and Y is not equal! by right, in an neutral atom, X should have 4 electrons and 4 protons while Y should have 20 protons and 20 electrons. So this shows that both X and Y lose electrons. Only Metals lose electrons. Hence option (D)

29. R has 4 electrons involved in bonding. Hence R is in group 4. option (B)

30. given X contains acid ---> from universal indicator, X should have a pH less than 7. As for the reaction between KI and Pb(NO3)2, it will give a yellow ppt of PbI2 :

2 KI + Pb(NO3)2 ---> 2 KNO3 + PbI2 ( PbI2 is yellow ) option (A)

SECTION B (STRUCTURED )

1a) ammonia b) Chlorine
c) Lead (II) oxide
d) Magnesium chloride
e) Brass

2(a) chemical analysis Not tested in sec 3

a) zinc hydroxide / white / soluble in excess giving colourless solution. [1.5]
iron(II) hydroxide / dark green / insoluble in excess [1.5]

b) (i) Magnesium, sodium, caesium and beryllium [½]
(ii) Sodium, aluminium, magnesium and chlorine [½]
(iii) Hydrogen, sodium and caesium [½]
(iv) Carbon and tin [½]

3 a) ionic / ionic / covalent / covalent / covalent / covalent [2]
b) giant / giant / simple molecular [2]

c) MgO is ionic and giant structure is strong and stable, hence it has higher
melting point. whereas the SO3 is covalent bonding and a simple
molecular structure. [2]

d) Na2O(s) + H2O(l) ---> 2NaOH(aq) [1]
SO3(g) + H2O (l) ---> H2SO4(aq) [1]

4 ( chemical analysis not tested in sec 3 )
a) A Copper(II) carbonate [1]
B Carbon dioxide [1]
C Copper(II) chloride [1]
D Silver chloride [1]
E Copper(II) nitrate [1]

b) CuCO3 (s) + 2HCl(aq) ---> CuCl2(aq) +CO2(g)+ H2O(l)
CuCO3(s) + 2H+ ---> Cu2+(aq) +CO2(g)+ H2O(l) [2]

5 (oxidation and reduxtion not tested in sec 3)
a) i) +6 ii) +3 [2]
b) Aluminium [1]
c) gain of oxygen or increase in oxidation state [1]
d) Cr2O3 is oxidizing agent. [1]

6 a) i) yes, they all have similar formulae
ii) yes, peroxides and super oxides are likely formed at the
elements below the group.
b) O- , O2-
c) i) H+(aq) + OH-(aq) ---> H2O(l)
ii) 2I-(aq) + Cl2(g) ---> 2Cl-(aq) + I2(s)
iii) Zn(s) + 2H+(aq) ---> Zn2+(aq) + H2(g)

7 a) i. P6O4 ii. P3O2 [2]
b) It is an non-metal oxide
it is covalent bonding
it has no free electron and no mobile ions when molten. [3]

SECTION C (FREE RESPONSE)

1 a) i) Mg(s) + S(s) ---> MgS(s) [1]

iii) Mg :24 + S: 32 à MgS : 56
3 4
12g 16g

Actual: 16g of Mg is used, Sulphur will be used up first in the reaction. [1]
Hence sulphur is the limiting agent. [1]

iv) S MgS
32 56
16g 28g 28g of MgS formed [1]
b) CaCO3 (s) + H2SO4(aq) à CO2(g) + CaSO4(s) + H2O (l) [1]
100 24000
y 1200 [1]
y = 100 x 1200/ 24000
= 5 g (CaCO3 is reacted) [1]

Percentage purity = 5/6 x 100%
= 83.3 % [1]

2 a) i) % of Na = 12.5/45 x 100%
= 27.8%

ii) Na H C O

27.8 12. 14.3 56.7

27.8 1.2 14.3 56.7
23 1 12 16

1.2 1.2 1.19 3.54

1 1 1 3

Empirical formula = NaHCO3
iii) Mr of empirical formula (NaHCO3 )= 23+1+12+ 16x3 = 84
Mr of molecular of NaHCO3 =84
n = 84/84 = 1, Hence, molecular formula = NaHCO3 [1]

b) i) NaHCO3(aq) + HCl à NaCl (aq) + CO2(g) [1]
ii) 84 24
45 x

Conc. Of HCl = 91.3/36.5
= 2.5 mol/dm3
mol of HCl used = 280/1000 x 2.5
= 0.7 mol
hence, vol of CO2 produced = 0.7 x 24dm3
= 16.8 dm3

c) [ chemical analysis, not in syllabus ]
Add equal volume of sodium hydroxide and small spatula of
aluminium powder into a sample solution. [1]
Warm till the aluminium dissolves. [1]
Effervescence and pungent smell gas produced turns red litmus
paper blue. [1]

3 a) methyl orange [1]
b) 22.8 cm3 21.5 cm3 28.7 cm3 [1]
√ √ [1]
c) 25.0 cm3 [1]
d) H2SO4 + 2NaOH à Na2SO4 + 2H2O [1]
e) average of sulphuric acid used = (22.8 + 21.5) / 2 = 22.2 cm3 [1]

mol of H2SO4 / mol of NaOH = 1 / 2
mol of H2SO4 = ½ x mol of NaOH
0.05 x 22.2/1000 = ½ x 25/1000 x mol of NaOH
mol of NaOH = 0.0444 mol/dm3

Disclaimer: only the MCQ answers are from miss pang, answers from section B and C are done by another teacher. Miss Pang is not responsible for the accuracy of the answers!

Old Blog Revived!

Hey pupils,

I was so forgetful and I didnt remember my password and my poor blog was not manned.

I was so shocked that I noticed messages tagged on the C-Box that had vulgarities and profanities on it.

Please do not do such a thing, for if I want to pursue this issue, I can.

I welcome any of you to raise questions again!!!!

Sanny, you asked if you are not with me anymore, could you still ask me questions. Answer is YES!!!

Thank you Mr Chan for helping me to answer the questions . . . I really welcome you to visit the blog.

The Chronicles Of 3 Little Pigs!

Another chronicle written by my sister.

Enjoy!

******************************************************************

The wolf which attacked the three little pigs had died from the fall off the chimney, but the story, or the chronicle of the 3 little pigs did not quite end there.

That fatal accident had created a huge stir-up and earned raved reports from the press. The proud wolves found that snub hard to stomach, and that incident had, to a certain extent, affected the operation of the local Bee Hiang Hiang store. Thanks-giving was round the corner, yet there was hardly any pig caught to serve as the main ingredient. The scarcity of pork made pessimists in the Wolf-Village turn to other food-alternatives, and many lived on a vegetarian diet.

This food crisis drove everyone in the Wolf-Village to desperation, and the wish for a sumptuous meal during the festive season brought the brains of Wolf-Village together, to stage a comeback. The review committee hired the well-learned Professor Wolff to conduct an independent review of that fatal accident. Analysis showed that the huff-puff method passed down from several generations before was obsolete and was no longer effective in toppling the brick houses built by the pigs. The R &D done by the pigs in Housing Development Authority (HDA) was indeed remarkable, and the suggestion made by Professor Wolff to solve this problem was to burn the brick house and force the pigs out of their sty.
He calculated that the brick house needed at least 100 000 kJ of energy to be completely engulf in fumes, and complete combustion of 1 mole of coal released approximately 100kJ of energy. The molecular mass of this special coal, coal W, designed by Professor Wolff, was 800.00g. Detailed calculations showed that 1000 mole of coal W was needed, which would weigh 6.023 x 10 23 x 800g x 1000 = 4.8184x10 29g.

As soon as the required amount of coal W was produced, everyone from the Wolf Village was mobilized to transport the coal. The Huff-Puff method was abandoned, but the transportation left everyone huffing and puffing. The target sty for the first attack to be launched was the sty built by the 3 little pigs who were responsible the many months of distress suffered by villagers in the Wolf Village.

It was by no means an accident that the 3 little pigs survived. Although the previous ordeal was a victory for them, they did not rest on their laurels but worked on improving the safety aspects of their estate. They knew that although their houses were “huff-puff-proof”, they were nevertheless not fire-proof and would engulf in flames should a fire break out.

The smart 3 little pigs had long designed a hot air balloon that could support the mass of the 3 of them should there be a fire. Careful calculations and experimentation showed that in order for the hot air balloon to support their weight as well as the necessary amount of coal for continual burning, 2400dm3 per second of hot air was needed. One mole of a specially-designed, fuel efficient coal, coal P could provide 1 mole of hot air, which is 24dm3 upon combustion.

Thus in order for the 3 of them to stay in the air for 1 hour, 60 x 60 x 100 = 360000 mole of coal P was necessary. The molecular mass of coal P is 600.00g. Thus the total mass of coal P required was 600 x 360000 = 216000000g. Wow!!!


The time was ripe when Professor Wolff saw strong wind blowing in the direction of Pansy Village, the village where the 3 little pigs stayed.

“Comrades! Start the fire! ” ordered Professor Wolff, as he sat a distance away from that brick house, sipping red wine, waiting for succulent pork to be served soon. Professor Wolff choked on his drink when he saw the roof of the brick house shoot-open, and the 3 little pigs flying-off with a smirk on their face in the hot air balloon! The sudden attack had failed to restore the reputation of the wolves being the most-capable animals in PW town (consisting of only Pansy and Wolf Village), but further undermines the standing of Wolf Village in PW town. My goodness!!!

It appeared that the coming Thanks Giving dinner in Wolf Village had no choice but to serve many salad dishes, and there was a real prospect that a vegetarian diet might stay for good.

by: xue yin ( another miss pang )

My sister and shana inspired me ( not shana's fault, so please don't blame her ) to offer one of my chem classes on a written assignment ' The Chronicles Of The Mole '.

Being a weak english person, I try my best to write an event regarding the mole.

Enjoy...

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Huai Ren was waiting outside the A & E. The police had notified him of Jenny’s accident.
After the operation, he was informed by the surgeon that Jenny had escaped death and would be transferred to intensive care unit.
Huai Ren entered the room. Accordingly, Jenny had sprained her neck and fractured her ribs due to the crash. The fractured ribs pierced through bronchiole and the doctor had to give her pain killers through injections. Jenny’s arms suffered from deep cuts due to the broken windscreen.
Huai Ren walked towards Jenny and lamented at her misfortunes.
She was not like this before, at least 1 year ago.
Jenny had suffered from post natal syndrome ; after her maternity leave, she needed to deal with the day-to-day operations of the company and these had proven too much for her. Her dad had suggested Huai Ren to take over the CEO position so as to lessen her duties. Recently, the company was faced with problems of cash flow. A large sum of funds was trapped in an acquisition project of a promising company’s shares.
Jenny insisted Huai Ren had misappropriated the company’s funds.
Huai Ren left the ward for he knew if she woke up, he would not be the person Jenny would want to see.
After visiting hours, someone entered Jenny’s ward.
He took out a syringe and held Jenny’s arm. With a swift movement, the hollow needle pierced through the skin and into the vein. 2.25mg/dm3 of Warfarin was injected into the bloodstream via the vein. He had done his calculations well. For every 13 kg of body weight, there is an equivalent amount of 1 litres of blood. So, Jenny would have around 4 litres of blood if she weighed 50 kg.
The maximum concentration of warfarin that her body could take should not exceed 5.0 mg per body of blood. Since concentration can be defined as amount of substance dissolved in 1 L, which is 5.0/ 4 = 1.25 mg/dm3. An overdose of warfarin will lead to bleed profusely as blood will not clot.
He could visualise the shock on the nurses’ faces when they saw her bleeding while doing their rounds the next morning. Blood would be oozing non stop from her cuts.

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ms pang:)

2005 SciChemistry MCQ

2005 MCQ
1) A * explanation *less dense means light, so we use the upward dispalcement method( see notes blog )
so, reject option B. B is for heavy gases ( downward displacement method )
option C is for insoluble gases.
2) C
* explanation *
when particles at 50'C ( liquid ) becomes 120'C ( gases ),the energy of the particles increases, the spacing between the particles becomes far apart and hence the attractive forces between the particles decreases.
3) C* explanation *81 is nucleon number ( proton + neutrons ) / atomic mass37 is proton number ( proton = electron )therefore, 81-37= 44 neutrons.
4) C* explanation *Element X has a valency of +1Element Y has a valency of -2
therefore, when you use the criss-cross method, the formula is X2Y1
5) D

* explanation *

Element Q has 4 valence electrons

---> group 4 ( since number of valece electrons = group number )

Hydrogen and chlorine are non-metals.

So, non-metal & non-metal = covalent compound.

properties of covalent compound = low melting point ( see notes blog )

6) D
* explanation *look at what is given to you: you have 0.3 moles of C3H8.to find volume of gaseous productsso, which is the product they want? from the question, there is CO2 and H2O?answer: look at the state symbols, CO2 is in (g) state!!!mole ratio of C3H8 : CO2 is 1: 3no. of moles ofC3H8 = 0.1,1unit = 0.1,3 units = 0.1X 3 = 0.3 moles(please dont be careless and choose option B!! we have only found CO2's mole, the question wants VOLUME ) so,using P.K.X fav sentence: 1 mole of any gas = 24 dm3 at r.t.p,so, 0.3 mole = 0.3 X 24 = 7.2 dm3
7) B
* explanation *
during the process of neutralization, the temperature will increase ( see notes blog )that is why options C and D are out!now, when neutralization finishes, the ecess alkali added will make the temperature of the solution back to room temperature. Hence a decreasing gradient.
8) B
option A: when a more concentrated acid is used, the gradient of the graph will be steeper instead of gentle because the rate of reaction is faster.option C: when fewer amounts of reactant is used, the amount of CO2 produced will be less. So, it will not reached the same level as graph 1.option D: when powdered reactant is used, speed of reaction should increase, instead of decrease!

9) B
* explanation *

option A, D are out because all potassium salts are soluble!

remember the K-N-N-Na theory.

option C is out. Potassium sulphate is a salt, not a base.

answer is potassium carbonate neutralises the acid.

10) C

* explanation *

when halogen is Y added to X and Z, there is no reaction, this means that Y is the least reactive.

so, down the group of 7, reactivity decreases, so, Br- is the least reactive.

so, Y = Br-

if X can displace Y and Z, then X is the most reactive.

so, X = Cl-

11) B
12) D
* explanation *option A: coke is not used to oxidised slag!! coke is used to burn to give carbon dioxide and carbon monoxide!

option B: limestone is used to decomposed to form calcium oxide and carbon dioxide.

the calcium oxide is used to neutralise slag.

option C: molten iron is heavier, so it is at the bottom, and not floats on the slag!

13) D

14) B

15) A ( see textbook for the uses of cracking )

16) A

* explanantion *

in the complete combustion of organic compounds, only carbon dioxide and water are formed.

17) D

18) C

* explanation *

only compounds with C=C bonds will decolourise aqueous brmine.

other C= structure will not decompose aqueous bromine.

19) C ( see textbook )

20) D* explanation *polyester = many units of ester group.
Terylene contains ester linkage.Nylon contains amide linkage.Poly(ethene) contains many units of ethene .Protein contains amide linkage.

Remedial Timeslots for 3E2 Pure Chemistry

Dear 3E2,

These are the timeslots for our InTeNsIvE TrAiNiNg PrOgRaMmE.

Please bring your stationaries, Five Year Series and Chemistry Textbook and File.
Venue: 3E2 classroom

16/06/08

Elements, Mixture and Compounds

Time: 11.15am to 12.45 pm

17/06/08

Structure of solids, Bonding

Time: 9am to 12 pm

18/06/08

Balancing Equations

Time: 2pm to 4 pm

Note:

I am having lessons for 4a,4e and 5a on 16th and 18th, so i cannot schedule your 'programme' eariler.

The lesson will end early if we finish our planned programme. Please do not be late for lessons.

miss pang :)

Reply to Germaine's Question : Is hydrogen a metal or non-metal

GERMAINE: hydrogen is metal or non metal?

My Reply: Hydrogen is a non-metal! However, it loses electrons to form H+ ions. ( so, i guess that is why Germaine will question its identity ).
The reason is it is more stable.

However, in tertiary levels ( JCs / Polys/Uni ), Hydrogen can also gain electrons, which is H- ions ( hydride ). There exist many metal compounds in which metal bonds with hydrogen and hydrogen gains ELECTRONS from metals. Such compounds are known as Metal Hydrides!

Thankfully, not in your syllabus!

ms pang :)

Reply to Mark's Question

Mark asked: ' i thought carbon-carbon is a quadriplet bond? and is in diamond, which is a giant colvent bonding. '

My reply to HJ's question was ' Are there any COMPOUNDS with carbon - carbon quadruple bond. '

Your comment was for diamond.

Firstly, diamond is made up by many many CARBON atoms joined together through covalent bonding. It DOES NOT have any other elements ( only carbon atoms ) in the composition of diamond. So, it is not the same as HJ's question as diamond is an element, not a compound.

Secondly, Quadruple bonds means one element shares 4 electrons with another element, and vice versa. Total 8 electrons within the 4 bonds.

For diamond, each carbon atom forms only one bond with another carbon atom. Which means each carbon atom forms 4 single bonds with 4 other carbon atoms!

ms pang:)
p/s: I am not taking a break.... was busy with the preparation for philippine's trip!

Reply to HJ's Question: Are there any compounds with quadriplet bond?

Hj: ms pang,is there such thing as quadriplet bond?

my reply: Should not have at your level. The maximum number of bonds between two atoms is only triple bond. eg:

dot and cross structure of nitrogen molecule

Structural formula ( read as ' N triple bond N ' )

As for the presences of quadruple bond... yes.... mainly in transition metal. Eg: Chromium.

I double check with miss wendy heng regarding HJ's question and I almost forgotten that in uni, we did manage to draw quadruple bond!!! ( many thanks to her ).

Just for your information... not in your secondary syllabus.....

chromium acetate

I edited this diagram so that you can see the quadruple bond easier... the original diagram is blur and show 5 bonds due to low resolutions.

I didnt draw these structures, i got it from this website:

(1) http://www.gcsescience.com/a25.htm ( nirogen molecule )

(2) wwwchem.uwimona.edu.jm:1104/courses/chromium.html ( chromium acetate )

p/s: is KING = Gareth? .. i assume HJ as 'hong jie'

ms pang :)

Chemistry Remedial For 4E1/4 Sci-Chemistry and 3E2 Pure Chemistry

Dear 4E1/4 and 3E2

In view of the upcoming MYE ( mid year exam )2008. There will be remedials for these days:

4E1/4 ( 3e2, be patient. Your timeslot is written below 4E .. so read on)

Our remedial will resumes from this saturday ( 26 april 08 ) onwards. Reason for cancelling the remedial on 19 april is due to real busy day of mine from morning.

The remedial will be conducted at only 1 slot: 10 am till 11.30am at AVA.

Target audience... 60 pax of you.

Topic: Chemical Analysis ( Cation/Anion)

This is a SUPER difficult and important topic ; this topic worths at least [5 mks ] in exam EVER YEAR without fail.

Since this topic needs alot of practice... we will continue with more practise for chemical analysis on 3 May 08. Same time, same venue.

You are advise to turn up for both sessions so you can have maximum exposure to this topic. Should you choose to attend only 1 of the above sessions, you may feel lost as practise is a continuation process.

3E2

Please inform your parents you have remedial.

Session 1- Revision: Structure of Atoms & Bonding ( 26 april 08 / 8.30-9.30/AVA )

Session 2- Revision: Formulas & Balancing Equation ( 3 may 08 / 8.30-9.30/AVA )

I will be going through FYS on 30 April. So all of you please stay back after your last paper. Have your lunch before our revision.

For administration purpose and monitoring of results, these are the pupils who attend sat remedial:

22 march 08

anas, michael, jason, yazid, cheryl, natasha, cheng hong, ronald

29 march 08

jessica, weifen, jolene, farid, anas, michael, jason, cheng hong, natasha, cheryl, jeffery

05 march 08

farid, jeffery, cheng hong, david, michael, anas, meiling, jolene, natasha, cheryl, jia min, yan ne, pei yee, weifen

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The preparation for O-Level Exam is similarly to preparing for a Marathon.....

Before you run, you need to warm up. However, with 'conditioning your body' for the run, it is impossible to have a marathon because it may lead to sprains and you may not even complete the run!!!

Slow and steady wins the race.

cheers,

ms pang:)