O Level Chemistry: Organic Chemistry – Addition Reaction

29 Jun

Posted by: sean in: Chemistry Notes & Tips

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Hello everyone,

Today is the last day of the 5 days Accelerated Learning Techniques seminar that i have been attending. So far so good! Event has been awesome and i have learned something new each day on getting our human mind & heart to learn things more efficiently and effectively, so that you will remember for the Rest of Your Life! Students under my wings before should know what i mean yeah?!

I look forward to 2 hours later where the event start rocking again. Meanwhile, before i leave my house, i just want to touch abit more on Organic Chemistry. I have heard from many students for the last 2 weeks that they dont really understand how to apply to the examination questions on Organic Chemistry, based on the information that were taught in school…

Let’s start the discussion by defining Hydrocarbons.

Hydrocarbons are compounds which contain Carbon and Hydrogen only. They occur abundantly in coal, petroleum and natural gas.

Saturated Hydrocarbons are those in which the combining capacity of the carbon atoms is as fully used as possible in bonding with hydrogen atoms, e.g. the alkanes.

Unsaturated Hydrocarbons are those in which the combining capacity of the Carbon atoms is not fully used. Unsaturated hydrocarbons are characterized by double or triple bonds between carbon atoms, e.g. the alkenes.

As mentioned previously, there are other compounds that contain elements like Oxygen, Nitrogen, Sulfur and other halogens (besides the Carbons and Hydrogen Atoms) –> we call these compounds collectively as Organic Compounds. There is a chance that they also have C=C double bonds.

Let’s continue by trying out one Multiple Choice Question (MCQ) as shown below:

Quick Check 1:

Which compound has an addition reaction with chlorine?

A. C2H4
B. C2H6
C. C2H5OH
D. CH3CO2H

PS: Try it out and leave your answers in the Comments Section right below this post. I encourage everyone to learn something here by participating actively by posting comments and suggested answers

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6 Responses

Jennifer
29|Jun|2008 1

Hey Sean.

My answer would be A.
as ethene is an alkene that undergoes addition reaction with a halogen, most of the time the halogen is bromine.

Reply
Gary
30|Jun|2008 2

Hello.

My answer is A too.Its because of the C=C bond that allows the reaction to be possible.

Reply
sean
02|Jul|2008 3

Hey Jennifer,

You are spot on! Hope things are going fine on your side.

Indeed, all unsaturated hydrocarbons undergoes Addition Reactions such as Bromination / Chlorination / Hydration / Hydrogenation.

One thing to note is that when we say “unsaturation”, it refers to any
unsaturation in the hydrocarbons. So it applies to Alkenes (carbon-carbon double bond) and Alkynes (carbon-carbon triple bond, not emphasized in schools, but it is somehow inside your GCE O Level Syllabus).

Hope this helps!
Sean

PS: I will be conducting an Intensive 1-2 days Intensive Mastery Organic Chemistry
Workshop in last weekend of June. Will post more details in this blogsite soon.

Reply
sean
02|Jul|2008 4

Hi Gary,

Good to see you contributing to this blogsite again.

C=C gives the unsaturation (and thus the reactivity) for Addition Reactions to occur.

As shown by my previous comments, Alkynes (C-C triple bonds) also allows Addition Reaction to happen.

Cheers,
Sean

PS: I will be conducting an Intensive 1-2 days Intensive Mastery Organic Chemistry Workshop in last weekend of June. Will post more details in this blogsite soon.

Reply
Qasim Raza
10|Jan|2009 5

my answer is A because it belongs from the alkenes family

Reply
sean Reply:
February 9th, 2009 at 2:58 pm
Hi Qasim,

You are absolutely correct. Keep checking more exam-based chemistry questions under “Chemistry Qns & Ans” under CATEGORY on the right hand side of this blog.

Where are you from?

Hear from you.

To Your Academic Success in Chemistry,
Sean
Master Trainer
Author

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