All my students have heard me talked about the doing experiments in “real” laboratories as well as the life of a chemists in the laboratories. Recently, i was at one of the local university and was managed to get a few pictures of undergraduates having their practical sessions in the academic laboratory. I thought it would be beneficial to let those students that are considering to further their higher educational studies in the specialized areas of Chemistry, to have a better idea with some pictures of work in laboratories.

Recently, i received several enquiries and questions from students on the color of copper hydroxides and copper carbonates.

I understand why the confusion. This is because in the local Secondary Schools, many of the Science (Chemistry) teachers are only showing the students of the Blue Color PPT when they test for the Cu2+ cation using alkaline solution such as dilute NaOH or aqueous Ammonia Solution. The Blue Color PPT are due to the formation of insoluble Copper Hydroxide which is very distinct.

Many of students are confused and thought all Copper Salts have a Blue Color PPT. This is certainly NOT TRUE.

In SPA on Qualitative Analysis, the Aim in the experiment is to assess on your ability to:
–> Make observations and readings and record them in a suitable format.

With this in mind, most of the time, they will give you all kinds of unknown samples and ask you to carry out a series of tests and note down your observations. In the end, you will be prompted with more questions and eventually they will ask you to identify the unknown sample.

Question might go like this:

Several parents and students alike have asked me on the possible practical questions that can come out for the SPA examinations.

I have this to say - SPA is in fact very very simialar to the GCE O Level Practical Examinations that we had last time.  There is not much difference between the chapters/topics that we have studied for the last 10 years. Basic Chemistry is essentially Basic Chemistry. The theories does not differ that much during the 10 - 20 years period. As such, all the practicals experiments will always revolves around the few main topics and you should be aware of it.

Many students have been asking me on the things that need to take note when they are doing their SPA, and how not to loose marks to their teachers that have their “eagle eyes” on them.

School-based Science Practical Assessment (SPA) is a pretty new initiative by the Singapore’s Ministry of Education (MOE) to test the students on their ability to follow procedures correctly when carrying out an experiment to test for a certain theory or concepts.

Below is a Table that can help us to identify cations in an unknown solution. This is very important in Qualitative Analysis Tests.

Besides SPA and Practical Examinations where the following table will be provided, you will need to memorize the table in order to answer QA questions that come out for Multiple-Choice Questions as well as Structured Questions.

But no fret, it is not that difficult to memorize it. Start by looking at Cu2+, Fe2+, Fe3+ and NH4+ because they have very distinct colours changes:

• Cu2+ –> Blue PPT
• Fe2+ –> Green PPT
• Fe3+ –> Reddish Brown PPT

Below is a question contributed by a local chemistry student (Student X) and an avid reader of this Chemistry Blogsite.

This will be a question that combines Mole Calculations & Qualitative Analysis topics. Give it a try!

Question:
In an experiment, 4.0cm^3 of 1.0mol/dm^3 aqueous copper(II) sulphate was mixed with 8cm^3 of 1.0mol/dm^3 aqueous sodium carbonate:

CuSO4 + Na2CO3 –> Na2SO4 + CuCO3

What did the reaction vessel contain when the reaction was completed?
A. A colourless solution only
B. A green precipitate and a blue solution
C. A green precipitate and a colourless solution
D. A blue precipitate and a blue solution

Halo students and avid readers,

This is one of the latest question sent in on Chemistry Practical. It’s a good question which I think some students would love to find out the answers as well, isn’t it?

“I wanted to ask what’s the correct/appropriate way to wash test tubes when you’re having a Chemistry practical? Because i’ve faced shortage of time, and it’s because i wasted a lot of time to wash my test tubes. Some students maybe more “kiasu” and they washed the test tubes multiple times to ensure it’s clean.

For example, i’ve 6 test tubes, but i’m required to do 7 or 8 experiments, so i’ve got to wash the test tubes. However, the test tube i’m re-using again, may have traces of the previous solution left and thus, affecting the result of the current one. Please do advise me on the correct and advisable method to wash my test tubes!

Is it okay to wash my test tube just with plain tap water or distilled water? Or both? And i do believe most schools provide a brush, which can fit into the test tube to remove solid particles or ppt which hardens and stays in the test tubes, am i required to use it, or it can be ignored?

This is approximately how i wash my test tube

Popularity: 16%

Hey can you pleaseeeeeeeeeeeeeeee help me with a qn.

This is for the chemistry spa I would be sitting tmr (SEC 3)

During an acid base titration, what are the possible sources of experimental error?

It would be great If I could get a reply today bcos as I have mentioned earlier I am sitting for the science practical O LEVELS tmr!!

THANKS.

Three most common ones are:

Popularity: 14%