This is one of the questions in Chemistry SPM 2009 Paper 2.
You're welcomed to email your answer to firstname.lastname@example.org. I'll reply and give comments as soon as possible.
This video shows the reaction between zinc and hydrochloric acid. Hydrogen gas is released in both conic flasks.
Points to ponder:
- Any possible reasons that contribute the different size of ballons in both experiments?
- How to measure the of rate of reaction?
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.
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
- Period 2 & formation of ionic bond
- Empirical formula of copper oxide
- Homologous series, chemical properties of alkene
- Rate of reaction, collison theory
- Heat of neutralisation
- Homologous series, empirical formula & molecular formula & isomerism
- Electrochemical series based on potential difference, factor of concentration towards the producf of electrolysis of an aqueus solution
- Redox reaction involving changing iron(III) ion to iron(II) ion, U tube
- numerical problems involving molarity, role of water on the properties of acid, confirmatory test of cation and anion in a sample of salt given
- Electrolytic cell: study how the type of electrode affect the product of electrolysis of copper(II) sulphate solution
- Rate of reaction between marble chip and acid
- Relationship between the concentration of acid and pH value. A look at the question.
I notice some blogs already uploaded with the answer. May be you all can have a look. Click here.
"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:
- food science
- forensic science
- environmental science
- education(teacher, or lecturer)
- plastic chemistry
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.
Soap and Detergents
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?
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!
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, email@example.com. The follows are some guides what you could write:
- Do you like your chemistry lesson?
- What activity in the class you like the most? Computer simulation of abstract concepts, group experiment, module, topical questions, answering tips, pair/group discussion?
- What are your suggestion to improve your chemistry lesson?
- How frequent do you visit this blog? Everyday?
- Which part in this blog do you like? Notes, tips, class activity, chemistry related website link, chemitry related knowledge?
I think the most important is to get to know the format of Paper 3 first.
Different scientific skills are evaluated in this paper:
- measuring and using numbers
- using space-time relationship
- interpering data
- defining operationally
- controlling variables
- planning an experiment(problem stat/ement/aim of experiment, hypothesis/variables, materials & apparatus, procedure and tabulation of data)
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.
Hopefully this analysis will help students who are trying their best effort before sitting the Chemistry paper on 8 Dec 2009
Measuring is one of the scientific skill included in Paper 3 Chemistry SPM. After going through different exam papers, examples of apparatus that I have noticed are as follows:
- stop watch(2003, 2008)
- Ruler (2003)
- Electronic balance(2004)
- Thermometer(2005, 2006, 2007)
- write the value of the measurement according to the accuracy of the apparatus. E.g. buretthe reading has 2 decimal places.
- All the values must be consistent and with units.E.g. the unit for buretthe reading is cm3. Please ensure all reading recorded with 2 decimal places.
- Hanna & Hanni who have contributed their analysis for Trial Kelantan paper.
- Dhiya who has sent her analysis for Trial Negeri Sembilan paper
- Anis Adibah who has comments on Trial Perlis paper. (Incomplete analysis on Paper 2)
- Syafiqah, Nazirah and Shakina who have posted their comments on Trial Kedah paper
- Liyana Yahaya and Rohiza comment on Mallaca Trial Paper
- Sofea and Syazwani comment on Selangor Trial Paper
- Lisa and Najihah sent their comments on Perak Trial Paper.
- which electrode is the negative terminal/positive terminal?
- mark the flow of electrons on the circuit
- which one is the oxidized substsance/releases electron/reducing agent?
- which one is the reduced substance/gain electron/oxizing agent.
- write half equation to show the reaction occur at each electrode
- write overall ionic equation for the reaction that occur in the U-tube
- Write observation.
Actually a student only need to remember some examples of oxidizing agent and reducing agent. Some examples of oxidizing agent and reducing agent are as follows
Lets take an examples when iron(II) sulphate solution and bromine water are used.
iron(II) sulphate solution is the reducing agent.
- iron(II) ion loses electron to form iron(III) ion.
- So, iron(II) ion is the oxidized substance.
- As electrons is produced, the electrode that dipped in the iron(II) sulphate solution is negative terminal
- electrons flow from this eletrode to another one through the external circuit.
- Observation: the green iron(II) sulphate solution turn yellow/brown
- Half equation: Fe2+ --> Fe3+ + e-
Bromine water is the oxizing agent.
- electrode that dipped in bromine receive electron from the external circuit.
- So, this electrode is the positive terminal.
- Bromine gain electron, so bromine is reduced to bromide ion.
- So bromine is the reduced substance.
- Half equation: Br2 + 2e- --> 2Br-
- Observation : the brown bromine water turn colourless.
As writing overall ionic equation, a student just need to add both half equation together.
Half equation 2Fe2+ + Br2 --> 2Fe3+ + 2 Br-
Try different questions to see how much you apply the tips given. All the best!
Photos shown my students were working in groups to set up apparatus to study transfer of electrons at at distance.
- students thought that the moles is the same with molarity.
- they thought that volume refer for both solution and gas.
- to have a clearer picture about the examination format
- to identify which areas you are still weak in.
- First part explain WHAT is it;
- Second part explain anything about the term. For example: How it happen; What is the properties; When....etc.
- What is the meaning of neuralisation?
2. What is empirical formula?
3. What is the definition of hydrocarbon?
Hydrocarbon is a compound that consist of carbon and hydrogen atom only.
4. What is meant by heat of displacement?
Heat of displacement is energy change when 1 mol of metal is displaced by a more electropositive metal by its salt solution.
I wish students who sit for SPM compile a list of common chemistry terms and understand them. The list helps as you can refer it anytime instead of flipping through your thick notes or reference books. If you have any doubts, I'll always ready to help.
Paper 1; Answer
Paper 2; Answer
Paper 3; Answer
Paper 1, 2, 3; Answer
Will upload more when I find more questions from other states. Any problems with this exam papers, just click comment and leave your message.
To determine the end point in the titration of hydrochloric acid and sodium hydroxide solution using acid-base indicator
Titration is an important method to determine the concentration of a solution.
Through Acid-base titration, concentration of acidic or alkaline solution can be determined.
Format of the Report
(Refer practical book page 103)
Schedule for PEKA is as follows :
4E : 15/9/09(Tuesday)
4D : 18/9/09(Friday)*
*Subjected to changes, might be earlier.
Will write more what I notice in the students' answers once I finish marking all the papers.
This paper touch on
- Electrochemical series
- Effect of temperature on the rate of reaction
Now, 2 councils in Selangor are about to start to collect used cooking oil from restaurants. The used cooking oil can be reprocessed to become bio-fuel and bitumen. Good approach!! For more details, read Councils to recycle used cooking oil from The Star.
Once added into soil, ammonium ferlisers which consists of ammonium ions are converted to nitrate ions by bacteria. Nitrate ions are absorved by plant roots. Nitrogen is used to make proteins in stalks and leavers.
Ionic Compound consists of ions.
- Positively charged ions and negatively charged ions are attracted by strong electrostatic force/ionic bond.
Covalent Compound consists of molecules.
- Molecules are attracted by weak intermolecular force/van der Waals force.
Therefore, ionic compound
- has high melting and boiling point
- can conduct electricity in molten state or aqueus solution. WHY?
- has low melting and boiling point
- cannot conduct electricity in all state. WHY?
Question 1 : Soap & Detergent; Food additives
Question 2 : Atomic Structure, Isotope, Heating and cooling curve
Question 3 : Determining of empirical formula
Question 4 : Preparation of soluble salt and insoluble salt
Question 5 : Carbon Compounds
Question 6 : Redox reaction in the transfer of electron at a distance and displacement of halogen
Question 7 : Alloy and Contact Process
Question 8 : Ionic Compound and Covalent Compound
Question 9 : Rate of reaction
Question 10 : Energy Profile Diagram and Heat of Combustion
I wish my students can review their mistakes carefully in this paper. Revise those topic that you're still weak for example: numerical problems related to the moles, rate of reaction, carbon compounds, redox, thermochemistry. and avoid careless mistakes during examination. All the best in the coming Trial JPWP!
Any comments, just write under this post, ok?
- 25 cm3 of ammonium hydroxide 1 mol dm-3 is pipetted into a conical flask and few drops of phenolphthalein is added.
- A buret is filled with aulphuric acid. Initial burette reading, V1 is recorded.
- Sulphuric acid is added into drops by drops into the ammonium hydroxide solution and the content of the conical flask is swirled.
- Continue adding sulphuric acid until the colour of phenolphthalein turn to colourless from pink.
- Final burette readind, V2 is recorded.
- Steps 1 - 5 is repeated by adding (V2- V1) cm3 of sulphuric acid from the burette into 25 cm3 of ammonium hydroxide solution in the conical flask(with adding phenolphthalein) and the conical flask is swirled.
- The content of the conical flask is then poured into an evaporating dish and heated until the volume become one third from the initial volume.
- The content is cooled into room temperature and filtered. The crystal (ammonium salt) is dried by using filter paper.
Throughout the lessons, everybody paid 100% attention. By the time they started working in groups, they started talking profesionally.
"use the coin as cathode"
"copper is connected to the positive terminal"
"Wow, teacher, come and have a look! Changes occur so fast!"
"TEAcheer, how does it happen?"
"The coin is so nice!!!!"
- dry cell
- alkaline cell
- mercury cell(e.g. battery in watch, calculator)
- lead acid accumulator(e.g. car battery)
- nickel-cadmium cell(e.g. rechargable battery mostly used in camera)
- lithium ion cell(e.g. laptop, iPod)
To all the participants, they have shown their enthusiasm throughout the program. They were proactive, creative in giving ideas and fluent in English. All the best to all the participants! Hope all of you will shine.....
Actually that’s one of her way to remember the prefix used for naming of carbon compounds.
Pergi – prop
Buat – But
Pedih – Pent
Hati – Hex
Hamba – Hept
Oh – Oct
No - Non
Dia - Dec
Detergent is a salt formed from the reaction between an alkyl hydrogen sulphate and an alkali.
Additives are added to make detergent more effective in cleaning.
Examples of additives that can be recognized are:
Funtion of different types of additives in detergent:
- biological enzyme : remove protein stains such as blood. E.g. amylase, proteases, lipase.
- whitening agent(include bleaches): convert stains to colourless substances, thus make clothes whiter and cleaner. E.g. sodium perborate and sodium hypochlorite
- optical whitener: make white clothes look whiter. E.g. fluorescent dyes
- fragrances : add freagrance to fabrics.
- drying agent: ensure the detergent powder is always dry. e.g. sodium sulphate & sodium silicate
- stabiliser : control foaming in detergent. e.g. alkyl monoethanolamide
- builder: enhance the cleaning efficiency of detergent by softening the water. e.g. sodium tripolyphosphate
Normally a box of detergent contains between 15 - 20% of detergent.
"They're so beautiful!"
Comments by my students when I showed them those colourful chemical in the test tubes.
From the left, it was iron(III) chloride, iron(II) sulphate, copper(II) sulphate, potassium dichromate(VI) and potassium manganate(VII).
"A place in Malaysia?"
As I discussed about the uses of semi-metal in the microelectronic industries, I asked my students where is Silicon Valley. Above are some examples of responses I get.
Ha ha.. Silicon Valley is at the sounthern part of San Francisco, US. It originally referred to the large number of silicon chip innovators, semi-conductors and computer industries in this area. However, now it refers to the region where most of the leading ICT-based company reside. Companies like Microsoft, HP, Apple, Intel, eBay, Yahoo, Google are headquartered here.
Can we imagine, what would happen to our world without silicon? A world without handphone, ipod, mp3, computer, etc.. out of imagination... My students get stunned when the ideas sank into their deep heart...
Stanford University and its graduates play an important roles towards the development of this area.
Picture taken at Stanford Universtity, San Francisco during my visit during Christmas year 2003.
I walk down the street.
There is a deep hole in the sidewalk
I fall in.
I am lost… I am helpless.
It isn’t my fault.
It takes forever to find a way out.
I walk down the same street.
There is a deep hole in the sidewalk.
I pretend I don’t see it.
I fall in again.
I can’t believe I am in the same place.
But, it isn’t my fault.
It still takes a long time to get out.
I walk down the same street.
There is a deep hole in the sidewalk.
I see it is there.
I still fall in. It’s a habit.
My eyes are open.
I know where I am.
It is my fault. I get out immediately.
I walk down the same street.
There is a deep hole in the sidewalk.
I walk around it.
I walk down another street.
(1) Reaction between silver nitrate solution and copper
(2) Reaction between copper sulphate solution and iron nail
For the first reaction, reaction between silver nitrate solution and copper
- copper is more electropositive than silver
- copper displace silver from its salt solution
- the silver solid, silver is displaced by copper from its salt solution
- Chemical equation:
For the second reaction, reaction between copper sulphate solution and iron nail
- iron is more electropositive than copper
- iron displace copper from its salt solution
- the brown solid, copper is displaced by iron from its salt solution
- Chemical equation:
Points to ponder: Why both reaction are examples of redox reaction?
- permitted food conditioners(modified food starch, Xanthan Gum)
- permitted preservative(sodium benzoate)
Food additives are added into food in small quantity to
- make food last longer
- enhance the flavour of food
- improve food appearance
Can you identify more examples of food additives in some food packages at your homes? Do these food additives bring any harm to human if being consumed in large amount? Looking forward comments on this topic...
Here is a story from a student, Chong. She said her practice and experience in great details.
You're welcomed to post your comments after reading the article...
From t0 – t1
1 In liquid state
2 Particles are arranged closed to each other but not closely packed together
3 Particles are not arranged in order
4 Energy increases
From t1 – t2
5 In liquid and gas state
6 Some particles are close to each but some are far apart
7 Particles are not arranged in order
8 Energy remains constant//does not increase
From t2 – t3
9 In gas state
10 particles are far apart from each other
11 Particles are not arranged in order
12 Energy increase