WAEC 2026 PRACTICAL CHEMISTRY SPECIMEN SOLVED (Number 2)

本站添加: 2026-05-12

[00:00:00]This is the number two question of 2026 WK chemistry practical the question on qualitative analysis. I dropped number one last night so rush to my YouTube then make sure you practice everything.

[00:00:14]This is number two. It says you are provided with a solid mixture label C.

[00:00:20]Carry out the following tests on sample C. Record your observations and inferences in a tabular form. A. Heat a small portion of sample C in a dry test tube. B. Add a few drops of iodine solution to a portion of sample C. C.

[00:00:36]Add dilute hydrochloric acid to another portion of sample C. Test any gas evolved with lime water. D. Filter the mixture obtained from C. To the filtrate, add potassium iodide solution.

[00:00:51]Now relax as I solve it the chemist AI way. Stay tuned.

[00:01:00]Now this is how the table looks like. So after making this kind of table test, observation, inference, you quickly go to the first question number one. It says heat a portion of sample C. You don't write grammar under test. Just write C plus heat. As simple as that.

[00:01:19]Then when you hit C in the laboratory, you are going to observe something. You will observe blackening or charing or sample turning black. So there are three things you can write. You write one of them. It's either you write blackening or you write char or you write sample turns black. Now in chemistry whenever you heat a sample and it turns black that sample is likely to be an organic compound. For instance sugar if you heat sugar it turns black because organic compounds contain carbon and carbon is black when heated. So you write under inference sample contains organic compound. You can also write organic compound present and you draw your line from the last line. Then you quickly go to number two. Add a few drops of iodine solution to a portion of sample C.

[00:02:10]Possibly they may ask you to divide the samples into three or four. So this is the second portion. And they said you should add iodine solution. So you just write sample plus iodine solution under test. Then you observe what happens.

[00:02:25]What you are going to get is blue black coloration. So you either write bluish black coloration or sample turns blue black or just blue black. Right? And you know, you should know that any moment you add iodine to a sample and it turns blue black, that sample must contain starch. So under inference, you write starch present. Once you finish writing test, observation, inference for a particular practical, you rule your line. Don't forget to rule line. If you don't rule line, you miss your mark. So you rule your line and go to the next question. The next question is add dilute hydrochloric acid to another portion of sample C. It doesn't end there. Test any gas evolved with lime water. Once you see lime water, that gas must be carbon file. But let's continue.

[00:03:19]You write sample plus dilute hydrochloric acid. What is the function of this hydrochloric acid? The function is to help release a gas if that compound is a carbonate. Now once you add HCl or even nitric acid what you are going to observe is effence or fizzling that is the sound that coke makes when you open it that sound sh so you write effvesence don't forget to write the description of the gas evolved during the effvesence so when you write effvesence you say colorless orderless gas then that gas remember the question says you should test it with lime water you pass it through lime water. What the gas does to lime water is to turn it to a milky color. So you say colorless orderless gas which turns lime water milky. The only gas that turns lime water milk is carbon fite. So you must write the gas. The gas is CO2. Now the target is not the gas. It is the compound that released the gas. Now let me teach you something. Whenever you have carbon 4 oxide released, it is coming from either carbonate or hydrogen carbonate because when a carbonate interacts with hydrochloric acid, there will be a chloride. Then the hydrogen from the hydrogen chloride, we pick one oxygen to form water and the remaining is carbon fide. So because carbon fide is released don't hesitate to write what the carbon fide is released from which is carbonate or bicarbonate H3 minus. So you write CO3 2 minus or H CO3 1 minus present because these are the two things that can release carbon 4 oxide. And after this you are done with question three. You rule your line a straight line. Remember the last question is about the filtrate. Remember they say you should filter the mixture obtained from that mixture obtained when you added dilute acid. You have to perform filtration to get the liquid part called filtrate. And then the question is asking you a question on the test of the filtrate. So the question says add potassium iodide to the clear solution. That is a filtrate. You simply write filtrate from C plus potassium iodide KI. And whenever potassium iodide comes to play, you are testing a metal called lead. So you are going to get yellow coloration as observation. So you write yellow coloration under observation. And once you see yellow coloration, lead two ion is confirmed.

[00:06:02]So you write laid 2 ion confirmed under inference. And this is exactly the answer to number two question on practical chemistry. Please don't fail to subscribe to my YouTube channel K Chem AI Educational Consultancy. And if you have a friend who is about to write this ya, share this video to him or