Sometimes i really wonder on the methods used by students to revise their academic subjects.

Over the years, i have received hundreds of emails enquiries from students asking for help in Chemistry questions. I am definitely glad to help them sought out their correct concepts on Chemistry Theories, but certainly not by answering any questions posed to me, without even given me their answers, workings, reasoning or thoughts.

Learning is about acquiring the knowledge and applying them , be it in tests, exams, projects or as a working adult.  Just by trying to get all answers to all the questions they have come across (without going through their own thoughts) does not mean they are going to Score the definite As in Exams!

Recently, i received severals emails from students asking me to supply them with answers asap to any questions that i have posted in this website. I will definitely share my suggested answers and reasonings/workings, but i believe the best way YOU CAN LEARN is to participate (by having your own answers and reasonings) before asking for the correct answers.

Just by reading does NOT allow you to master something, especially in academic Chemistry! So if you a student preparing for your O Level Chemistry Paper 1 in less than 10 days time, i would strongly urge you to try out the questions on your own first.

Here is a set of MCQ questions on Qualitative Analysis to prepare you for Chemistry Paper 1:

Question 1:
Which ion, in aqueous solution, forms a white PPT when dilute sulphuric acid is added?
A. Ag+(aq)
B. Ba2+(aq)
C. Cu2+(aq)
D. Fe2+(aq)

Question 2:
Which gas is evolved when an alkaline solution of sodium nitrate is warmed with aluminium?
A. Ammonia
B. Nitrogen
C. Nitrogen Dioxide
D. Oxygen

Question 3:
A colourless gas is denser than air. It neither burns nor supports the burning of a splint. What could be the gas?
A. carbon dioxide
B. chlorine
C. helium
D. hydrogen
E. oxygen

PS: Rmbr to try out the questions using the knowledge that you know

Hi everyone,

We had continued where we left off yesterday, on the famous chemistry experiment on Cola + Mentos Mint. In Version 1, we were using the 500ml Normal Coke Classic + Mentos Mint, but the experiment was not so successful due to the CO2 gas being released even before we managed to put in the mentos mint.

Today, in Version 2, we compared the reaction for the following:

Set A: COCA-COLA ZERO + MENTOS MINTS
vs.
Set B: PEPSI MAX + MENTOS MINTS

As in all chemistry experiment, we have tried to keep all parameters/conditions the same:
1. Surrounding Temperature the same
2. Surrounding Pressure the same
3. Volume is the same (both are 1.5L by volume)
4. Equal amount of Mentos Mints were added

PS: Let me know how you feel about this experiment. I would love to hear from you. Simply write your comments in the “Leave A Reply” section below

PPS: If you have a You-Tube account, it would be be great if you could give a rating and perhaps some comments of your own.  >> http://www.youtube.com/watch?v=626MFcOx6Lk =)

Hello everyone,

Time for us to talk about Chemistry Phenomenons and Everyday Chemistry in our Lifes.

Have you heard about the reknown COKE + MENTOS Reaction Experiment?

We have decided to carry out this experiment to share with readers on what has been observed.

Something went wrong during the experiment! Haha. Saw it? The experiment did not went so smoothly that i wish. But i will NEVER consider this as a failure. To me, it is just an unsuccessful experiment – cos i will get it RIGHT the next time!

Stay Tuned! We will come back soon with Version 2 of COKE + MENTOS!

PS: What is the reaction that occurs when Mentos is added to Coke? How can i improve this experiment? Drop me a comment or two. I would love to hear from you.

PPS: Rmbr there is no such thing as failures – there is only unsuccessful methods used, unsuccessful methods learned, etc

PPPS: If you did not do well for your recent O Level Chemistry Paper 2, remember you still have Chemistry Paper 1 coming up, worth 40 absolute marks (and 30%!!)

For those local students that did not do well for the O Level Chemistry Paper 2 on Oct 20th, do not be discouraged because there is one more chance for you to UP your Chemistry Grades.

You still have your Chemistry Paper 1 (Multiple Choice Questions) Exams in 19 days time. There is more than enough time for your to re-learn and re-fine your Chemistry Concepts and earn high marks for it.

There are 40 marks for you to bag in Chemistry Paper 1 and weightage is as high as 30%!

But there is one problem i usually see. Students tends to let off their guards and relax before the Paper 1 because:

1. Chemistry Paper 1 is the last paper of GCE O Level Exams and students already in “holiday mood”

2. Many students feel that Paper 1 (MCQs) is very easy .i.e relax mood….just go there select choices

They are certainly wrong about this. MCQs is the one that truly tests you on your concepts and applications.

In Paper 2 (Written Theory), questions are usually phrased and linked from one part to another, to help you to get some marks here and there.

But in Paper 1 (MCQs), you will score only either when you know the concepts really well and know how to apply, or when you are lucky. For me, i don’t believe in luck – i prefer to control my own destiny.

Now, that is the reason you see me starting this Mini Series on Tough MCQs.

And for those that wish to score an A1 for overall Chemistry Exams, i can assure you that MCQs will ultimately determine whether you get an A1 or A2! Trust me on that cause i have been through that, just like hundreds of students that i have coached before.

Below are sets of Exam-based MCQs for you to try:

Question 1:
When crystals of copper(II) sulphate are heated, the color changes from blue to white. This is caused by:
A. loss of water only
B. loss of water and sulphur trioxide
C. loss of water, sulphur dioxide and oxygen
D. reaction with carbon dioxide in the air
E. reaction with water vapour in the air

Question 2:
Which of the following salts can be crystallized from aqueous solution?
A. barium sulphate
B. calcium carbonate
C. potassium nitrate
D. silver chloride
E. zinc carbonate

Question 3:
Which one of the following hydroxides does not give a good yield of a salt with dilute sulphuric acid?
A. Iron(II) hydroxide
B. Magnesium hydroxide
C. Zinc hydroxide
D. Calcium hydroxide
E. Copper(II) hydroxide

PS: Do try it out and leave your comments below. Suggested answers will come in with reasonings.

SimpleChemConcepts.com has been listed in chemistry.com.sg – a listing that shows Specialist Chemistry tutors / coaches that provides chemistry tuition / coaching in Singapore.

chemistry.com.sg is one of the highest ranking website for both Google and Yahoo search engines when you type in terms related to “Chemistry” or “O Level Chemistry“. We are certainly glad to be considered by this Chemistry Listing site as one of the preferred / recommended Chemistry Coaches in Singapore.

NOTE:
For those taking their major Chemistry Exams next year, we have several things that will definitely interest you in Year 2009. This applies to BOTH Locals as well as Overseas Chemistry students. Do subscribe to our Newsletter or Blog-post Notifier (both located on the right hand column) for more updates!

Here is a question sent in via email by an avid student reader of this chemistry blogsite.

Hope to see some suggested answers below and the reasoning/explanation to it.

PS: Remember – Do not be afraid of making mistakes now. I rather you make mistakes now then during your examinations.

Question 1:

20cm3 of a gaseous hydrocarbon was mixed with 100cm3 of oxygen and the mixture sparked so that the hydrocarbon was completely burnt. The volume of gas remaining at the end of the combustion was 70cm3. After passing over soda lime, this volume was reduced to 10cm3. All gases were measured at 25C and at the same pressure.

(a) What volume of oxygen gas remained unburnt at the end?
(b) What volume of oxygen gas was used in the combustion?
(c) What volume of carbon dioxide was produced in the combustion?
(d) Deduce the formula of hydrocarbon.

From the previous post, we have started on our Mini Series on Tough MCQs.

Purpose is to enquire that students are exposed to tougher & tricky chemistry Multiple Choice Questions (Paper 1) that we have observed for the last 10 years.

How come i know them, you may asked? Cos i have been compiling and analyzing these questions for my students year-after-year, and sharing with them to ensure that they know how to avoid the common mistakes and traps that many other students have fallen into.

You know what – Usually this “tough” questions are Application Type Questions that just need a cool head and good chemistry concepts to get it right. It isnt that tough at all.

Let’s continue with more questions below:

Question 1:
Why is Sodium classified as Metal?
a) It is a pure substance
b) It is a good conductor of electricity
c) It exists as atoms, not molecules
d) It is very soft

Question 2:
Buckminsterfullerene was discovered in 1985 and it has a perfect sphere with formula C60. From this information, what can you deduce about it?
a) It contains only one element
b) It is a compound of 60 elements
c) It is a mixture of 60 atoms
d) It is a mixture of 60 elements

Question 3:
When mercury is heated, it forms mercury and oxygen,

Mercury oxide (s) –> mercury (l) + oxygen (g)

What can you deduce from the above information?
a) During the heating of mercury oxide, all three states of matter exist
b) Mercury oxide is a mixture
c) Mercury oxide is a silver solid
d) The composition of mercury oxide varies during heating

PS: Try out the questions and enter your suggested answers (and comments) right below, so that others can come in to share their answers and thought process.