What are the different types of JC Chemistry tuition classes available at your centre?

We have 3 modes of learning for students to choose from: weekly physical classes at Bishan; weekly online lessons via Zoom; and on-demand video lessons.

Are you the only Chemistry tutor conducting the classes or do you engage other tutors to do that?

Please be rest assured that I conduct all my classes personally and I do not engage other tutors to teach at my centre.

How well do your students perform after attending your H2 Chemistry tuition classes?

Most of my students showed improvements by at least 3 grades and more than 80% have attained distinction for A Levels. The earlier the students join my classes, the more confident I am in improving their grades.

What is your class size at Bishan?

Usually the class size is around 10 to 12 students. Max class size is 16 pax.

Is there makeup lesson if I miss a class?

Yes makeup lesson is available in the same week subject to availability. If makeup class is not possible, the student can view the recorded video lessons at Google Classroom.

Do you have trial lesson available? How much is it?

Yes we do. Fees for trial lesson are for Bishan class and for Zoom online class.

Does your centre offer O Level chemistry tuition? Do you teach IB / IP chemistry tuition? How about H1 Chemistry?

Chemistry Guru specialises in H2 Chemistry for JC1 and JC2 or IP Year 5 and IP Year 6 students only. Find out all the information about A Level H2 Chemistry and the detailed comparison between H1 and H2 Chemistry. We do not conduct lessons for H1 Chemistry, O Level Chemistry, IB Chemistry or IP Chemistry at IP Year 3 and IP Year 4.

Electrophilic Substitution Mechanism of Benzene - Organic Chem

In this video we want to discuss the electrophilic substitution mechanism of benzene using 2 reactions as example.

Nitration of Benzene

The first reaction is nitration of benzene to nitrobenzene.

Nitration of benzene to nitrobenzene

This reaction is done using concentrated nitric acid in concentrated sulphuric acid catalyst at 50 to 60 degree celsius.

The first step involves the generation of electrophile NO₂⁺ which is formed from the reaction between conc HNO₃ and conc H₂SO₄.

ES nitration step 1 - generate electrophile

In the second step, which is the rate determining step or slow step, benzene will react with the electrophile NO₂⁺.

ES nitration step 2 - electrophilic attack

For arrow pushing we have to draw the full arrow, which represents the movement of 2 electrons, from benzene ring (electron rich region) to nitrogen in NO₂⁺ (electron poor region).

The intermediate formed is highly unstable as the benzene is positively charged and it loses the resonance stability due to the opening of delocalised ring.

In the third step, the intermediate will deprotonate or remove a H⁺ to form product nitrobenzene. The H⁺ will combine with HSO₄^- intermediate to regenerate H₂SO₄ catalyst.

ES nitration step 3 - deprotonation and regenerate H2SO4 catalyst