Radical Substitution in 7 Min (6 Marks)

Name: Radical Substitution in 7 Min (6 Marks) | IB Chemistry R3.3 [IB2]
Description: IB Chemistry Reactivity 3.3, electron sharing reactions: radical substitution of an alkane with a halogen (part 2 of 5, for SL and HL). The three steps of the mechanism, initiation, propagation and termination, with every equation for methane and chlorine, and why one chlorine radical starts a chain reaction. Includes a six mark exam-style question solved step by step.

Plays on through the playlist · Free Radical Substitution | IB Chemistry R3.3 Radicals (SL & HL) (2 videos) on YouTube

What you'll learn

IB Chemistry Reactivity 3.3, electron sharing reactions: radical substitution of an alkane with a halogen (part 2 of 5, for SL and HL). The three steps of the mechanism, initiation, propagation and termination, with every equation for methane and chlorine, and why one chlorine radical starts a chain reaction. Includes a six mark exam-style question solved step by step.

In this lesson

0:00The question
0:11Overall reaction and initiation
1:06Propagation
2:09Termination
3:01Practice: ethane and bromine
4:05What earns the mark
4:41Exam question solved
5:35Recap
6:09Next Wednesday

Answers to the practice questions

Br₂ → 2Br•, with UV light above the arrow [1].
Br• + CH₄ → •CH₃ + HBr [1]; •CH₃ + Br₂ → CH₃Br + Br• [1].
Br• + Br• → Br₂ [1]; •CH₃ + Br• → CH₃Br [1]; •CH₃ + •CH₃ → C₂H₆ [1].

Try them at the end of the video first. Questions are original, in the style of the exam; marks are estimates.

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