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National 5 Chemistry

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Original post by Sweet_Candy
Can someone explain what reducing agent is


It's pretty mych using Carbon or Carbon monoxide to oxidise a metal (help it gain electrons) when you try to extract it.
Hey guys! This sounds stupid but I'm really stuck on types on reactions and I'm wondering if anyone could help me out? :smile:
I'm really not sure what each reaction does e.g addition, displacement, neutralisation, preciptiation etc. I'm not sure how to answer a question that shows an equation and asks "What reaction is this equation representing" Thanks in advance!
(edited 7 years ago)
Oh yeah what is a displacement reaction ? I might of learned it as a different name so just wondering
Reply 143
Original post by SSJBlue
Hey guys! This sounds stupid but I'm really stuck on types on reactions and I'm wondering if anyone could help me out? :smile:
I'm really not sure what each reaction does e.g addition, displacement, neutralisation, preciptiation etc. I'm not sure how to answer a question that shows an equation and asks "What reaction is this equation representing" Thanks in advance!


Original post by Ethan100
Oh yeah what is a displacement reaction ? I might of learned it as a different name so just wondering


A displacement reaction is basically when a metal higher up the Electro chemical series "displaces" a compound that has a metal which is lower (In the E.C.S) than that of the metal that is doing the displacing....

It's hard to understand so here's an example:

Iron + Copper Sulfate = IRON SULFATE + Copper

Notice how the "Iron" has took the place of the "Copper" in the sulfate compound and has essentially knocked the copper to the side. This is known as displacement and it takes place, Because iron is higher in the E.C.S than copper, hence why a reaction takes place.
(edited 7 years ago)
Original post by Jay431
A displacement reaction is basically when a metal higher up the Electro chemical series "displaces" a compound that has a metal which is lower (In the E.C.S) than that of the metal that is doing the displacing....

It's hard to understand so here's an example:

Iron + Copper Sulfate = IRON SULFATE + Copper

Notice how the "Iron" has took the place of the "Copper" in the sulfate compound and has essentially knocked the copper to the side. This is known as displacement and it takes place, Because iron is higher in the E.C.S than copper, hence why a reaction takes place.


Do they usually hide this in a question or will it list for example some metals and you say what metals would cause a displacement reaction ?
Original post by SSJBlue
Hey guys! This sounds stupid but I'm really stuck on types on reactions and I'm wondering if anyone could help me out? :smile:
I'm really not sure what each reaction does e.g addition, displacement, neutralisation, preciptiation etc. I'm not sure how to answer a question that shows an equation and asks "What reaction is this equation representing" Thanks in advance!


Addition = Adding something across double bond
Neutralisation = Acid + base - Salt + water
Precipitation = Solid comes out of solution, due to the fact it is insoluble.
Displacement = Already answered.
Original post by SSJBlue
Hey guys! This sounds stupid but I'm really stuck on types on reactions and I'm wondering if anyone could help me out? :smile:
I'm really not sure what each reaction does e.g addition, displacement, neutralisation, preciptiation etc. I'm not sure how to answer a question that shows an equation and asks "What reaction is this equation representing" Thanks in advance!


Yeah and a precipitation reaction is when two soluble liquids make an insoluble product. In a question they will give you two reactants that should be very soluble and the product should be insoluble in order for this kind of reaction to take place. To know the solubility consult your data booklet.

Addition is really taking and alkene and breajking the double bond and replacing it with simple molecules such as water or bromine. To make the bonds single and covalent.

A neutralisation reaction - there are 4 you need to know

Acid + Alkali gives you a salt and water

Acid + metal carbonate gives you a salt, water and carbon dioxide

Acid + metal oxide gives you salt and water

Acid + metal gives you hydrogen gas and a salt :smile:
Thank you so much! @Jay431 @The Wavefunction @studyranger :smile: Great help
(edited 7 years ago)
Original post by SSJBlue
Thank you so much! @Jay431 @The Wavefunction @studyranger :smile: Great help


No problem nice dragon ball Z image
Reply 149
Original post by Ethan100
Do they usually hide this in a question or will it list for example some metals and you say what metals would cause a displacement reaction ?


They could do both, But from what I've seen they give you a formula equation and you have to realise it's a displacement reaction.
Original post by studyranger
No problem nice dragon ball Z image

Haha it's my fav anime, I've also been watching the new Super series, which has been awesome so far :smile:
For the plastics section what to we need to know ?

+ Condensation Polymerisation
+ Addition Polumerisation

Anything else ?
Reply 152
Are there any model papers other than the SQA ones provided online? Done all of them and looking for some overall revision :smile:
Reply 153
Original post by SSJBlue
Thank you so much! @Jay431 @The Wavefunction @studyranger :smile: Great help


Also don't forget reduction and oxidation reactions.

You can find reduction at the back of the data book and for oxidation just flip the equation around.

Remember Combustion as well. When a hydrocarbon reacts with water to produce CO2 and water. Incomplete combustion leads to CO
Original post by SSJBlue
Haha it's my fav anime, I've also been watching the new Super series, which has been awesome so far :smile:


Cool I am planning to wathc all the great anime over summer can't wait :smile:
Some really smart nat 5 chemists in this thread :P Hopefully the exam goes great for all of you !
Original post by Ethan100
For the plastics section what to we need to know ?

+ Condensation Polymerisation
+ Addition Polumerisation

Anything else ?


Yeah and you should be able to draw a section of the polymer, showing three monomer units joined together... :smile:
Original post by Lewis H01
Yeah and you should be able to draw a section of the polymer, showing three monomer units joined together... :smile:


Yeah I think Ive got that :smile:
Would you need to know examples of synthetic and natural plastics ?
(Please say no :P )
Reply 158
Original post by Ethan100
For the plastics section what to we need to know ?

+ Condensation Polymerisation
+ Addition Polumerisation

Anything else ?


You need to know how to draw a chain of the monomer units when given the monomer.
If they give you a polymer you need to be able to identify the monomer used to make it. I don't think u need to name it, But you have to be able to draw the monomer.
You need to be able to differentiate between a condensation and addition polymer.
You need to be able to draw the repeating unit.

These all come under addition/condensation polymerisation.

I think it would be handy to know a few natural and synthetic polymers off by heart just in case you get a cheeky open ended question and you want to show off or something lol :wink:


Original post by Frank$
Are there any model papers other than the SQA ones provided online? Done all of them and looking for some overall revision :smile:


Yes there's a book u can buy, But it takes about 6 days to get delivered lol :P
Original post by Ethan100
Yeah I think Ive got that :smile:
Would you need to know examples of synthetic and natural plastics ?
(Please say no :P )


LOL ☺️☺️ Nah I don't think you need to know synthetic and natural plastics :smile:

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