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.

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

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.