ANNOUNCEMENT: CHEMISTRY CCT1

Dear all,

Just to remind you that the CCT is on Week 5 Thursday, 19 April 2007.

The topics to be tested include:
1. Periodic Table
2. Salts & Qualitative Analysis
3. Redox Reactions
4. Reactivity of Metals & Metal Extraction
5. Mole Concept and chemical calculations

Format of the Paper:
Closed book, 3 sections.
• 10 MCQ (10 mk)
• Structured Questions (15 mk)
• 1 Open-ended Question (10 mk)

Please start mugging now if you want to do well. *evil grin*

How Batteries work?

Yoz everyone,

So, we have all learnt how to create a battery using a fruit.

Now, Energizer actually has quite an interesting website on the working of Alkaline battery. http://www.energizer.com/learning/howbatterieswork.asp

Please visit the website and discuss in the 'comments' section:
1. What is the cathode of the battery.
2. What is the anode of the battery.
3. What electrolyte is used in the battery.
4. What reactions takes place at each electrode? Give the half equations.
5. How does electrons flow?

In addition, quite a number of you asked how a rechargeable battery works. The same website has a short description of it. You might want to read it too.


The human electrolyte? Do you think we can act as electrolytes?
Picture taken from http://www.exploratorium.edu/snacks/hand_battery.html

Revision for CCT: Redox

Guys, here's a website that will help you revise your REDOX:

http://www.chemguide.co.uk/inorganic/redoxmenu.html

These are the things you must be able to do after going through the website:

- Define Redox in terms of electron transfer and changes in oxidation state.
- Identify O.S. of a particular ELEMENT in a substance, e.g. What is Cl's O.S. in HOCl?
- Identify a redox reaction, the reducing agent and oxidising agent.
- Write half equations.
- Combine half equations to get ionic equations.

A whole list of practice problems can be found in this website:

http://www.chemtutor.com/redox.htm#osp


A pictorial representation of REDOX. Taken from http://www.emc.maricopa.edu/faculty/farabee/biobk/BioBookEnzym.html

Reactivity Series

Yoz, everybody,

Let's recap what we have learnt this week:

1. The reactivity series ranks the reactivity of various metals [More reactive at the top]. (Remember to come up with your own acronym)

2. The more reactive metals are able to DISPLACE the less reactive ones from their oxides or their salt solutions.

To help you visualise what happens at the atomic level during displacement of metals from the salt solution, go to the following website:
http://www.chem.iastate.edu/group/Greenbowe/sections/projectfolder/flashfiles/redox/home.html

For additional notes, you could go to this website:
http://www.wpbschoolhouse.btinternet.co.uk/page03/Reactivity.htm

Lastly, remember to plan your experiment (i.e. SPA) before coming for lab next lesson. You would only have 10 mins to complete the experimentation.

Enjoy!


The Promethean Flame (aka Thermit Reaction)
[Thanks to Jon Chiam]

Achievements by End of Term 1

Dear all,

Hi. We have all survived Term 1 and it is time to celebrate your successes in the past term.

I've done some results analysis and here are the lists of Top Students and Students who have improved tremendously.

Congratulations to all.

Auspicium Melioris Aevi



Updated after remarking.

More ... Qualitative Analysis

Yoz all,

Hope you are enjoying your hols. I'm sure you have completed your task assigned by Mr Clow Snide right?! If not, you will be banished to his Kingdom (where huh??) when I see you next week... *evil grin*

Anyway, I'm going to start a new discussion about QA.

From our lessons, we have learnt to identify H+, NH4+ and some metal cations based on their reactions with carbonate, zinc, litmus paper, alkalis and lead(II) nitrate. (Can still remember which test is for which ions??!)

If all these tests fail to give us any positive results, then we may conclude that "Group I metal ions may be present". I've told you that the flame test could actually be used to identify the metal ion present.

So here's a link for you to read about flame test:

http://chemistry.about.com/library/weekly/aa110401a.htm

The article states that "the flame test is limited by interference from other brighter colors and by ambiguities where certain different metals cause the same flame color".

Now, my question is: Can we use flame test to positively identify the metal ions? If so how? What is the principle behind this technique?

Let's discuss using the comments function. The one who contributes most to this discussion will get ..........




Picture taken from http://elementy.ru/trefil/36

The picture shows flames of three burning substances, each containing the elements sodium, strontium and boron (from left to right) respectively.

CCT in Term 2

Dear all,

Hi. Holidays coming soon, which also means more work. Hehe.

First of all, holiday assignments:

1. I-learning
Please log onto the AsknLearn portal for a i-learning on Reactivity Series of Metals. You would have to print out a worksheet and use it for the i-learning.

2. Revision exercise on VA
I shall be giving out a revision exercise on volumetric analysis. Some of the classes would have gotten it at the start of the year. All are to complete this piece of work during the holidays.

Lastly, there will be a CCT next term (between Wk 3-5, haven't decided yet). It will be the first CLOSE BOOK test that you are doing this year. So must prepare well ok!

Topics to be covered include:

1. Periodic Table
2. Salts & Qualitative Analysis (Knowledge of acid/base chemistry assumed)
3. Redox reactions
4. Reactivity of Metals & Metal Extraction [i-learning, term 2's work]
5. Mole Concept and chemical calculations [Sec 3's work]

The paper would include 3 sections:

• 10 MCQ 10 mk
• Structured Questions 15 mk
• 1 Open-ended Question 10 mk

If you have any problems during your revision, you can share your questions on this blog using the comments function.

Enjoy your hols!


Hexagonal-shaped rocks crafted naturally by the sea (Jeju, Korea).

Additional Questions for QA

Yoz,

To help you in your revision for the OBA, here's two problems for you.




You can discuss the answers by posting comments. =)

Why a Temple?

Yoz guys,

I've decided to build a Temple so that I can start collecting joss-stick money.

What's in the Temple, you may ask. Well, I don't know. Maybe things that I feel you need to know, but have no time to discuss during class? Perhaps interesting articles which you might want to read?

Humm....Whatever the case, just drop by to hug the Buddha's leg occasionally.