Flashcards
Substitution Reactions
Cards in this deck (13)
- 1What are photochemical reactions?Reactions that are started by light
- 2Complete the sentences: Haloalkanes are formed when _________ react with __________ in photochemical reactions. During the formation of haloalkanes, a ______________ atom is _______________ (replaced) by a halogen such as chlorine or bromine in a ___________ _____________ reaction.Haloalkanes are formed when HALOGENS react with ALKANES in photochemical reactions. During the formation of haloalkanes, a HYDROGEN atom is SUBSTITUTED (replaced) by a halogen such as chlorine or bromine in a RADICAL SUBSTITUTION reaction.
- 3What is the name of the process involved in the synthesis of chloromethane?Radical substitution
- 4Give the balanced symbol equation for the synthesis of chloromethaneCH₄ + Cl₂ --> CH₃Cl + HCl
- 5What are the 3 stages of radical substition?Initiation
Propagation
Termination - 6What happens during initiation?Sunlight provides enough energy to break some of the Cl-Cl bonds (this is photodissociation)
The bond splits equally and gets to keep one electron (homolytic fission)
These atoms are highly reactive radicals, Cl•, because each one has an unpaired electron - 7Give the equation for the initation stage in the synthesis of chloromethaneCl₂ --> 2Cl•
- 8What happens during propagation?Radicals are used up and created in a chain reaction
First Cl• attacks a methane molecule
The new methyl radical, CH₃•, can then attack another Cl₂
The new Cl• can attack another CH₄ molecule, and so on, until all the Cl₂ or CH₄ molecules are used up - 9Give the equations of the propagation stage in the synthesis of chloromethaneCl• + CH₄ --> CH₃• + HCl
CH₃• + Cl₂ --> CH₃Cl + Cl• - 10What happens during termination?If two radicals join together, they make a stable molecule - this terminates the chain reaction
- 11Give the 3 possible equations for the termination stage in the synthesis of chloromethaneCH₃• + Cl• --> CH₃Cl
CH₃• + CH₃• -->C₂H₆
Cl• + Cl• --> Cl₂ - 12What are the problems associated with radical substitution?You get a mixture of products even if you are trying to make a single particular product
It can take place at any point along the carbon chain, forming a mixture of isomers - 13What is one solution to reducing the chance of by-products forming?Have an excess of a reactant
For example, in the synthesis of chloromethane, there could be an excess of methane. There'll be a greater chance of a chlorine radical colliding only with a methane molecule and not a chloromethane molecule
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- User has deleted their subject information Flashcards on Substitution Reactions, created by Deleted user on 12/03/2018.
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- Deleted user · Mar 2018
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- Mar 12, 2018
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- Created by Yinka F · Mar 7, 2018
- Copied by Yinka F · Mar 12, 2018
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