Overseas and beyond (VI)

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Day 6:
It feels as though I've spend a month in Brunei, the rich experiences that seemed to last so long and so vividly.

The recent past seems so distant and the day I ORDed feels like it's ten months ago.

Time passes by, flowing, without being conscious of the beings that it sweeps away. Each experience, treasured, cherished, fades away from memory, acquiring a surreal, sepia tinge.

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Overseas and beyond (V)

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Day 5:
Probably the most memorable day of the entire journey. After all, who wouldn't remember the first time they tried eating worms?
It tasted plain weird. I was in a daze after that, with why did you eat the worm?! repeating endlessly in my mind like a badly-tuned radio. And the plantation worker below actually ate the fat worm live!

We visited the padi fields to try our hands at planting the seedlings. It was really therapeutic, planting the padi seedlings. Rows after rows, rows after rows. It's immensely gratifying, doing something tangible that has an immediate effect.

The girls were hysterical as they sank in the mud while the guys found their place in the world as they frolicked in the mud. I suspect that the latter are reincarnations of swines.

Actually, I was rather tempted to join them in the mud but desisted. See, I'm all matured now.

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Overseas and beyond (IV)

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Day4:
The second day spend at the school was eye-opening, with their kids putting up some traditional Malay dances and ours doing a hiphop dance routine.

We bid farewell most unwillingly with this very hospitable school and their teachers.

From what I could remember, our Singapore students treat foreign visitors with aloof diffidence. I could only hope that they would not be disappointed by the lukewarm welcome they would most probably receive the next time they come over to Singapore for immersion trips.

We visited some museums to understand more about the culture of Brunei in the afternoon. Can't say much about this, it was rather fun at that moment in time. The curators were eying the group tensely as the kids frolicked about, treating the museum like a playground.

To be honest, the kids treated everywhere like a playground, so we tend to attract unwanted attention everywhere.

It was followed by some shopping at the pasir malam where I saw this:

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Overseas and beyond (III)

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Day 3:
Visited a school in Brunei and was overwhelmed by their warm welcome. Kids lined the corridors to clap and play musical instruments. Door gifts were given to all of us while teachers shook our hands with much delight.

It was as though we were royalty!

The principal began to give a speech in their cosy library. Since I don't understand Bahasa Malayu, I started to look around the room, all the while pretending to take photos. To my horror, I was the only one wearing shoes in the entire room. How embarrassing!

Assuming an air of professionalism, clutching to my tiny compact camera, I feigned indifference. Immediately, after the speech, I hurried out of the library to shed my shoes.

The teachers of Brunei are really well-off. Many of them carry DSLRs and MacBooks. Envious, envious. Incidentally, Brunei is a really affluent country with a benevolent sultan who provides free healthcare and education to all Bruneians.

With idle interest, I began to observe some teachers as they read a book. The interest intensified when I realised what the three of them were reading.

They were pointing a picture of the female reproductive system and giggling demurely while the rest of the room listened attentively to the principal's speech. Such naughtiness! From the gentle way the teacher were giggling, one would imagine them to be sharing a quiet joke on the weather, not looking at reproductive systems!

And they actually posed for a photo as their colleague took a photo of them with the book resting on their laps, diagram of the menstrual periods on one page and a drawing of the male reproductive system on the adjacent. It's really LOL.


We immersed ourselves in the culture of Brunei as the teachers cordially guided us along.

The camaraderie among the teachers was impressive. They sat down, played with some drums together, laughed and shared stories. Our Singapore teachers pointed out that they would hurry back to Brunei, feeling blessed, if they were to spend one torturous month working in a Singapore school.

Why must working in Singapore be so tiring?

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Overseas and beyond

Just returned from a trip to Brunei and am feeling all mellow within. The joy that I experienced was unparalleled. It opened my eyes wide to the world outside.

To be honest, I was like the frog in the well, knowing nothing but the confines of the bricks and yet, arrogantly believing that I was the center of the world. It was good to be reminded of the foolishness of my own self-absorption once in a while.

Brunei is a prosperous country with tech-savvy residents, well-developed infrastructure and it reminds me of Singapore (without the traffic congestions, concrete jungle and supercilious folks).

Day1:
Met up with 16 kids and 2 teachers and all of them are Malay Muslims. I got a shock and immediately regretted my choice.

I didn't know what I was signing up for when I hesitantly agreed to be an impromptu tour guide. It just seemed too good an opportunity to miss : a $1, 127 trip for free, a 6 day-stay in a 4-star hotel, daily allowance of $30/day, food and lodging provided. All I had to do was to lead some children around. It ought to be easy, shouldn't it?

And it turned out not only to be easy but great fun. The kids were really spirited and bounced around with such energy that I felt incredibly old and frumpy in comparison. I felt so frail and I'm only twenty! And the teachers were really cool people too.

Had a room in the hotel all to myself. It was really quite luxurious, this feeling of lazing about in the air-conditioned room with nary a thought about the future.

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Tuition for Kindergarten and its Horror

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Was searching online to see if there are people who require guidance for their learning. Didn't expect to see anything profoundly disturbing.

Yet, I did. I was shocked by some of the advertisements, searching for tutors - NIE trained, current teacher, 5 years of experience, female etc - for some kindergarten kids.

Kindergarten!

Tech-savvy parents were actually searching for tutors for kids who are barely 5 years old. Ain't that amazing?! And it wasn't just one family, but a few of them!

Perhaps I'm being presumptuous but the poor kids! So young and yet they're forced to sit and stuff their brains with cold, unfeeling facts. What about playing? What about exploring? What about the faculty of wonderment?!

The education system - so highly competitive! - is driving desperate parents to take desperate measures to put their children ahead of the pack.

Sigh.

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A New Journey

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Am going to Brunei soon as a tour leader.

My aunt got back recently from this stint as a tour leader and enjoyed herself completely, repeatedly saying that it was a good experience. The kids were well-behaved and the teachers guided the students well. All she had to do was some minor admin and help herself to the mountains of food.

Apparently, there's always food to be had in Brunei, particularly if you're on a cultural exchange trip.

Am a little hesitant to embark on this journey. In fact, I'm particularly fretful and am sleeping fitfully.

New experiences frighten me. Why so? I guess it's because I am afraid of making mistakes and the attending criticisms. I'm scared that I'd not be loved by the people around me for failing to be perfect, to be beyond reproach.

It's a bit hard, almost unimaginably difficult to let go of all those limiting self-beliefs. How does one find courage to pursue one's dreams when one doesn't know what it is?

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Actions

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About to begin on the tenacious art of batik painting.

Bit nervous as though I'm meeting an ex-lover after not seeing her for 12 months.

Fear that I won't be able to create works of startling beauty.

It's time, time to take the leap despite self-doubts, fears and limiting beliefs.

No one ever moves forward when they focusing on the past.

Perhaps art can be one of the stream of income, passion merged with livelihood.

Please please, have the courage to move forward regardless of what others feel or think.
*
Need to learn to focus on others and reply in a tactful manner.

'No one nor schools have a monopoly on intelligence and diligence. I'm sure everyone can do well.'

Don't tease or joke in a manner that might prove to be hurtful. Learn to control your mouth! Don't let it get away with its wild comments, tame it! It's not a separate part of you and shouldn't be allowed to act on its own accord.

Learn to listen, for only through listening and inspection, that one can achieve growth and enlightenment. Listen and observe, listen and observe. Speak less, Learn more; Talk Less, Observe more.

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Camping

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Was working as a camp facilitator for the last two days and was shocked by the behaviour of the children. I didn't expect them to behave in such an atrocious manner and was rather affected. Can't quell the unnerving sensations coursing silently throughout my mind.

The kids were very prone to violence.

One kid threatened to fight with another facilitator and stormed off with 4 other boys without my foreknowledge nor permission. I was struggling to control my panic after noticing that a quarter of my charges were gone. After I found him, I counselled him and wanted him to apologise, all the while controlling my anger.

'But, I don't like saying sorry and almost never say it,' he whined and pouted.

As his punishment, I made him gather the rest of the class around me. It was a mistake, one that I shouldn't have made. He actually went about collecting the guys, punching those who refused to obey him. Nightmare.

Another guy went absolutely nutty, clutching the left arm of a poor kid. 'May I break his arm? May I?' He asked so politely and seriously while tears pooled at the corners of his eyes. His friends giggled at his sombre tone and the British accent that his voice affected. The whole scenario was so bizarre and disturbing that I have no idea what to make of it, be it now or then.

He was also the guy who stood in a corner and cried during the camp for no rhyme and reason.

Then, there were games.

Games, games. It should be safe, shouldn't it?

Turned out that one guy slapped another when the latter refused to participate. Slap. One tight slap across the cheek. For refusing to participate.

I wasn't so nefarious when I was younger, so violent and aggressive. (I hoped.) Such violence and aggression!

From the camp, I learnt. Kids, nowadays, are genuinely spoiled with overworked parents who have little time for them. Teachers have to scream and shout to bring their point across. Come to think of it, the teachers, like parents, are overworked.

Some kids were really sweet and precocious, but the bulk of them were little terrors. 

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Taking Charge

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Always torn between decisions.

How I wished someone would make all the choices for me so that I could blame him for all the consequences.

It's so much easier to thrust one's fate into the hands of others, to abscond from the responsibility of one's future.

It's harder, much more difficult to make decisions when the effects of each path feels so stunningly clear and daunting.

But make a choice I must, and let the Lord guide me. Amen.

Dear Lord, I trust in you, and follow the almost-silent calls that You send to me daily. The whispers are always there though I fail to hear them sometimes. Please continue to nourish me, so that You can be proud of me. I thank You for Your parental indulgence and strictness and love and kindness and patience and understanding and guidance.

For someone who isn't a Christian, I tend to pray very often. Would rather believe that there is a benevolent force looking after us than to believe that the world is random and meaningless.

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Lab Report on Ion Selective Electrodes

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The lab report below was submitted as part of the coursework for CM2142 Analytical Chemistry. Please do not plagiarise from it as plagiarism might land you into trouble with your university. Do note that my report is well-circulated online and many of my juniors have received soft copies of it. Hence, please exercise prudence while referring to it and, if necessary, cite this webpage.

1.      Aim
To determine the concentration of cupric ions in aqueous solutions using ion selective electrodes by calibration curve and titration with ETDA.

2.      Results and calculations
By calibration curve
Preparation of 1000pmm standard solution
Concentration of Cu2+ solution used= 1000ppm = 1 g L-1Mass of Cu2+ in 50mL of solution =  = 0.05g
No. of moles of Cu2+ in 50mL of solution                =   = 7.868 x 10-4 mol
Concentration x volume = no. of moles                                 0.1 x v = 7.868 x 10-4
 Volume of 0.1 M Cu2+ used =                 = 0.007868 L = 7.87mL 7.90mL

Table 1: electrode potential at various concentrations of Cu2+
Volume used to prepare standard
Concentration of Cu2+ /ppm
Log [Cu2+]
Electrode Potential /mV
7.90 mL of 0.1 M Cu2+
1000
3
272
5.00 mL of 1000ppm
100
2
241
5.00 mL of 100ppm
10
1
211
5.00 mL of 10ppm
1
0
181
5.00 mL of 1ppm
0.1
-1
151
-
Unknown
-
272
Graph 1: Graph of electrode potential against log [Cu2+]
From the graph, y= 30.2 x +181, where y is the electrode potential (mV) and x is the log [Cu2+].
Since the unknown Cu2+ solution gave an electrode potential reading of 244 mV,
log[Cu2+] in unknown solution = (244-181) ÷ 30.2 = 2.086
Concentration of unknown Cu2+ solution = 10 2.086 121.89 ppm 122mg/L =0.122 g /L
Molarity of unknown Cu2+ solution = 0.122 / 63.546 0.00192 mol/L
By titration
Given the molecular mass of EDTA = 372.24 g/mol,
Theoretical mass of EDTA needed to make 0.01M EDTA solution
= (100/1000)L x 0.01 mol/L x 372.24 g/mol   = 0.37224 g
Mass of EDTA used to make EDTA solution = 0.3720 g
\Molarity of EDTA solution prepared = (0.3720 g ÷ 372.24 g/mol) ÷ (100 ÷ 1000)L » 0.0100 M

Volume of EDTA added (ml)
Electrode potential Reading (mV)
Volume of EDTA added (ml)
Electrode potential Reading (mV)
0.00
235
4.70
165
0.50
233
4.80
118
1.00
230
4.90
103
1.50
229
5.00
98
2.00
227
5.20
95
2.50
224
5.40
93
3.00
220
5.60
90
3.20
219
5.80
86
3.40
215
6.00
82
3.60
213
6.20
82
3.80
212
6.40
81
4.00
207
6.90
80
4.10
204
7.40
78
4.20
205
7.90
76
4.30
200
8.40
74
4.40
197
8.90
73
4.50
191
9.40
71
4.60
185
9.90
71
Table 2: electrode potential with addition of EDTAGraph 2: graph of electrode potential against volume of EDTA added
From the graph above, the equivalence point occurs at = 150mV with volume of EDTA added= 4.80mL
EDTA4- + Cu2+ è [Cu(EDTA)]2-
No. of moles of EDTA = 0.00999 ×   0.00004796 0.0000480 mol
No. of moles of Cu2+ = 0.0000480 mol
Molarity of Cu2+ solution =  = 0.00100 M
3.       Discussion
Ion-selective electrodes
Ion-selective electrodes (ISE) are membrane electrodes that measure the electric potential of a specific ion in the presence of other ions. They are used in biochemical, biophysical and environmental analysis for determining the concentration of various ions in aqueous solution.
 In this experiment, a cupric ISE is used. This instrument consists of a thin solid-state crystal membrane (right diagram) which specifically permits the movement and transport of Cu2+ from a high concentration to a low concentration and generates a potential difference which can be measured by a voltmeter.
Increasing Cu2+ concentration results in more Cu2+ ions attracted towards the electrode, hence producing a greater current flow. This measurement is done at equilibrium, where the rate of exchange of Cu2+ across the membrane is the same. The electrodes can be calibrated by measuring the electrode potentials in standard solutions of various concentrations and the concentration of unknown ion in solution can then be determined from the calibrated curve obtained.
Advantages of using a ISE
ISE are frequently used for analysis because[1]:
·      ISE are responsive in a linear manner to the log of activity of analyte.
·      It does not consume the sample being tested.
·      It has negligible contamination.
·      It is unaffected by turbidity and color.
·      It has a rapid respond time.
·      It is relatively inexpensive as the basic setup requires only a meter capable of reading millivolts, a probe for the analyte of interest, and chemicals to adjust the ionic strength of the solution.
·      With careful use and frequent calibration, ISEs can produce accurate results reliably.
Due to the above reasons, ISE are frequently employed to characterise reactions.
Limitations of ISE
The accuracy of ISE measurements may be decreased due to the activities of other ions in the same solution[2]. ISEs are not ion-specific; they are sensitive to ions with similar physical properties to some extent. For many applications these interferences are insignificant and can be ignored.
The cupric ISE will not give an accurate reading if Ag or S are present in the solution. Mercury ions also have very high interference and can only be tolerated in low concentration compared to the Cu.
Bromide and chloride ions both have selectivity with the cupric ISE and will cause a significant error if they are present in concentrations greater than one tenth of that of copper ions.
The accuracy of the results is affected by the presence of interfering ions. Should there be contaminants, the results may be inaccurate.
Experimental techniques: by calibration curve

Before use, the electrodes must be calibrated by measuring a series of known standard solutions, made by serial dilution of the 1000ppm solution. For a full calibration, 100 ml of solutions containing 100, 10, 1 and 0.1 ppm was prepared. To prepare the various concentrations of solutions, successive dilutions were carried out carefully.  This must be done with utmost precision: should the concentration of a preceding solution be wrongly prepared, this will result in a propagation of errors in the concentrations of successive solutions, thereby further leading to inaccurately measured conductance for all these successive solutions.
To each standard solution, 0.9 mL of ISA (5M NaNO3) was added. The Cu electrode works most reliably when samples and standards are mixed with ISA to give a background matrix of around 0.1M NaNO3. This keeps the total ionic strength of the sample and standards constant, therefore ensuring that the electrode potential reading increase proportionally with increment in Cu2+ concentration (as observed in graph 1).
After determining the electrode potential of the Cu2+ sample and with the aid of the prepared calibration graph, the concentration of the sample can then be derived.
Experimental techniques: by titration with EDTA
Ethylenediaminetetraacetate (EDTA) is a polydentate ligand where the 2 N and 4 O atoms can chelate to the Cu2+ ion to form an octahedral complex[3].
Figure 1: reaction of EDTA with Cu2+
As seen from the equation, EDTA4- + Cu2+è [Cu(EDTA)]2-, EDTA reacts with Cu2+ in a 1:1 ratio to form a [Cu(EDTA)]2- complex. As the volume of EDTA added increases, the amount of free Cu2+ ions in the solution decreases. EDTA forms a cage-like structure containing Cu2+, thereby isolating it from the solvent molecules.
The cupric ion selective electrode which measures the electrode potential of the remaining Cu2+ ions in the solution will register a drop in the electrode potential. The initial addition of EDTA produced a slow and steady decrease in electrode potential reading until when 4.80 ml of EDTA was added. This change marks the equivalence point of the titration. After that, the addition of excess EDTA continued to result in slow and steady decrease in electrode potential reading because there was little free Cu2+ present in solution.
 Using titration with EDTA to determine the Cu2+ concentration was less tedious as the electrodes need not be washed with deionised water so many times. On the other hand, this method may be time consuming should there be many data points to be taken; time is required for the reaction to be react thoroughly before the ISE could register a stable electrode potential value.

Precautions
Prior to each measurement, the electrodes on the dip cell are rinsed a few times with a dropper containing the solution to be tested. This displaces any residual ions that may be on it. For the same reason, the beaker is also rinsed several times with the solution for which conductance is to be measured.
The probe was then blotted dry. This prevented an accumulation of static charges (which might occur if it was rubbed dry) and ensured that the readings obtained were more accurate. A clean, dry tissue was used each time to prevent cross-contamination.
Time is allowed for the solution to equilibrate before its conductance is measured. Also, a magnetic stirrer was placed in the beaker containing the solution to be measured; this ensures even mixing such that a more representative electrode potential may be recorded. The stirrer may generate sufficient heat to change the solution temperature; to counteract this effect, a piece of insulating material, such as Styrofoam sheet, could be placed between the stirrer and beaker.
The standard Cu2+ solutions were measured starting with the lowest concentration of 0.1ppm to the highest concentration of 1000ppm; this minimizes the error incurred particularly if there were contaminants from previous tests.
The experiment was carried out at an environment with relatively constant temperature as variation in temperature can lead to measurement error. When not in use, the probe has to be kept moist at all times to maintain its sensitivity.
Alternative method of measuring concentration of an unknown sample
In this experiment, the concentration of copper ions is derived from a calibration curve and titration with EDTA. These results may be double-checked by recording the absorbance of the blue-colored copper-containing sample and calculating its concentration with Beer-Lambert’s law. According to this law, A = ε c l, where A is the absorbance, ε is the molar absorptivity, c is the concentration of the absorbing species and l is the path length of the sample[4]. Once the absorbance of the sample is known, its concentration of copper can then be calculated.
4.       Conclusion
The concentration of the Cu2+ in the unknown solution determined using the calibration graph is 122 ppm or 0.00192M. Using titration, the concentration of the copper solution determined is 0.00100 M.
               5.     References 
 [1] Rundle, Chris. Advantages of Ion-Selective Electrode Measurements. Article retrieved on 25 Mar 2012:  <http://www.nico2000.net/Book/Guide3.html>
[2] Prince George’s Community College. Structure of EDTA.  Article retrieved on 25 Mar 2012:  <http://en.wikipedia.org/wiki/EDTA>
[3] Rundle, Chrs. Cupric Ion-Selective Electrodes. Article retrieved on 26 Mar 2012:  <http://www.nico2000.net/analytical/copper.htm>
[4] Sheffield Hallam University. Beer Lamber Law. Article retrieved on 27 Mar 2012:                                            < http://teaching.shu.ac.uk/hwb/chemistry/tutorials/molspec/beers1.htm>

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