Red Cabbage Juice as An Acid Base Indicator

Have you ever tried this red cabbage(Brassica oleracea var. capitata f. rubra) before? It's often used for salads. Some of friends do not dare to tried even a small piece of it because of its colour.

The cabbage is red/purple, due to the presence of a colour pigment called anthocyanin. Its colour depends at the pH value of the soil. 

More acidic soil, the leaves grow more reddish.

More alkaline soil, more greenish yellow cabbage is produced.

Due to this special characteristic, red cabbage juice can be used as a home made acid base indicator. For more details, please visit http://www.funsci.com/fun3_en/acids/acids.htm.

Try to look around your garden too. May be you can colloect some flower petals and test whether there is any colour when difference acidic/alkaline substances are added. Who knows you might discover your own natural indicator too! Please don't forget to share with me your new finding too!!!

Predict the Product of Electrolysis of Aqueous Solution

Most students are having a big problem in electrochemistry.  Normally questions related to electrolysis of aqueous solution are their common mistakes.

This is one of the questions in Chemistry SPM 2009 Paper 2.

Electrolysis Of Potassium Iodide Solution from sweemoi khor

If you need guide to predict the product of electrolysis of aqueous solution, click here.

You're welcomed to email your answer to sweemoi@gmail.com.  I'll reply and give comments as soon as possible.

Rate of Reaction between Zinc and Hydrochloric Acid

This video shows the reaction between zinc and hydrochloric acid.  Hydrogen gas is released in both conic flasks.

Points to ponder:

1. Any possible reasons that contribute the different size of ballons in both experiments?
2. How to measure the of rate of reaction?

Relationship Between Concentration of Acid and pH Value

Chemistry SPM 2009 Paper 3 Q3 from sweemoi khor

This question appeared in Negeri Sembilan Trial paper. Those students from this state are very lucky.

Some students said they didn't carry out this experiment in their chemistry laboratory. Thus they have no idea how the experiment plan should be.

To my dear current form 4 students, Let's discuss this question together.

Common Chemicals

Common salt - sodium chloride
Table Sugar - sucrose
Vinegar - ethanoic acid
Vitamin C - ascorbic acid
Baking soda - sodium bicarbonate
Dry ice - solid carbon dioxide
Aluminium foil - aluminium
Copper wire - copper
Clean sand - silicon dioxide
Diamond - carbon crystal

SPM 2009 Paper 1, 2 & 3

Paper 2

1. Alloy
2. Period 2 & formation of ionic bond
3. Empirical formula of copper oxide
4. Homologous series, chemical properties of alkene
5. Rate of reaction, collison theory
6. Heat of neutralisation
7. Homologous series, empirical formula & molecular formula & isomerism
8. Electrochemical series based on potential difference, factor of concentration towards the producf of electrolysis of an aqueus solution
9. Redox reaction involving changing iron(III) ion to iron(II) ion, U tube
10. numerical problems involving molarity, role of water on the properties of acid, confirmatory test of cation and anion in a sample of salt given

Paper 3

1. Electrolytic cell: study how the type of electrode affect the product of electrolysis of copper(II) sulphate solution
2. Rate of reaction between marble chip and acid
3. Relationship between the concentration of acid and pH value.  A look at the question.

Paper 1
 
  I notice some blogs already uploaded with the answer. May be you all can have a look. Click here.

Chemistry Related Career

   One day, one of my students came to approach me after the end of her chemistry lesson.
    "Teacher, is it good I further study in chemistry?" She asked.

   "Of course, yes! But which part of chemistry do you like the most?" I said.

   She started to fall into a deep thought.

   Actually, deep in my heart, I'm glad my students have interest and plan to study more about chemistry.

  There are many fields requires chemistry knowledge:

1. food science
   
2. forensic science
3. environmental science
4. oceanology
5. geochemistry
   
6. education(teacher, or lecturer)
7. biotechnology
8. medicine
9. engineering
10. plastic chemistry
    
11. metallurgy
12. agrochemistry
13. pharmaceuticals
14. dietian

  The list is incomplete. Chemistry works in any industrial, educational, scientific, or governmental field. A chemistry student is equipped with excellent analytical and mathematical skills which help them to solve problems in their job.


  Perhaps I'll post more chemistry related career later. So, what's your choice?

 For further reading, you might visit American Chemical Society.

Medicines

Medicines

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What are Soap and Detergent?

Most of my students are wondering how to identify soap and detergents? In fact, it's not easy to identify through their physical properties.  Soap and detergent are different in term of their chemical structures and their chemicals required during preparation. Hopefully the slideshow below will help you to to have a better idea.

Soap and Detergents

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What's in your food?

I find this book particular interesting. The author, Chia Joo Suan who is a food chemist give us a closer look at food through comprehensive and easy-to- read guide.

Food is important. We consumer food not only to sustain our life but also for their taste, nutritional and medicinal values. Are the food we are taking safe? Many food additives are added to enhance food quality. Do we realize what are they? Do these food additives bring any side effects to our health in the long term?

Chemicals for Consumer

The discovery of chemicals manufactured for consumers such as cleaning agents, food additives and medicines has helped us improve our health and standard of living. Today, different type of these chemicals are produced to meet the needs and preferences of consumers. Therefore, understanding the chemistry of these chemicals will help a consumer select and use them wisely.

Hopefull this holiday assignment will make you realise the importance of many chemicals available in your daily life.  Any doubt, don't be hesitate to ask. Enjoy your holidays!

Chemistry Review 2009

   The 2009 School Year at last comes to the end.  This is the first year I teach in this school.  5C, 5F, 4D & 4E were my students . At first, I found it was a whole new experience to teach in a all girls school.  Anyhow, I like my girls and happy with the their effort in their chemistry class.

  But i'm curious. Do my students like their chemistry lesson with me? What do they think about my teaching strategy/approach?  Knowing my students better would help me to improve in the coming school year.

I wish my students could email me their opinion to me, sweemoi@gmail.com. The follows are some guides what you could write:

1. Do you like your chemistry lesson?
2. What activity in the class you like the most? Computer simulation of abstract concepts, group experiment, module, topical questions, answering tips, pair/group discussion?
3. What are your suggestion to improve your chemistry lesson?
4. How frequent do you visit this blog? Everyday?
5. Which part in this blog do you like? Notes, tips, class activity, chemistry related website link, chemitry related knowledge?

How to get prepared for Paper 3 Chemistry SPM?

Many of my students keep on asking me about how to score Paper 3.  They are not sure whether they are ready for it or they are applying the correct learning strategies...

I think the most important is to get to know the format of Paper 3 first.

Different scientific skills are evaluated in this paper:

1. observing
2. classifying
3. measuring and using numbers
4. inferring
5. predicting
6. communicating
7. using space-time relationship
8. interpering data
9. defining operationally
10. controlling variables
11. hypothesizing
12. planning an experiment(problem stat/ement/aim of experiment, hypothesis/variables, materials & apparatus, procedure and tabulation of data)

   The scientifil skils are acquired by the students slowly when they plan, carry out experiments and make a report in their class.  PEKA is another way of assessment to evaluate students' scientific skills and attitudes too.
 
  So, the best strategy I would suggest is to go through the above list and identify which one you are still weak in.  Go through the past year questions or trial question from different state and try to study why an answer for a particular skill is considered as excellent answer(Score 3).

All the best! All the SPM 2009 Candidates.

Volume of Gas

1 mol of any gases, as you name it, oxygen gas, helium gas, hydrogen gas, neon gas, etc.... occupy the same volume in the room condition.

This concept is known as molar volume at room condition, which is 24 dm³ mol^-1.

Question Analysis of Paper 3 Trial Chemistry 2009 from Different State

I have done some analysis on the questions from all the trial papers that I  have gathered. It seems that some  questions are quite popular. However, I haven't get trial papers from Penang and Sarawak.

Hopefully this analysis will help students who are trying their best effort before sitting the Chemistry paper on 8 Dec 2009

Question Analysis Of Paper 3 Trial Chemistry from Different State from sweemoi khor