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Chemistry ATP (Important points for Both IGCSE and O-level)

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abcde said:
Nibz said:
Hey guys, Assalam-o-Alaikum :)
These are some of the tips for Chemistry ATP (both O-level and IGCSE)

Some precautions:
=> Experiments involving poisonous gases like Nitrogen, Ammonia and Bromine -> Carry out the exp. in Fume Cupboard or in a well Ventilated Room.
Umm, Nibz, nitrogen is not toxic/poisonous. Otherwise, we'll all be dead breathing 78% of nitrogen in air 24/7! :p


Oxygen is a poisonous gas , if we inhale it directly from an Oxygen source

We don't die from oxygen in air , because other gases are in the atmosphere with it


So I think nitrogen might be a poisonous gas if inhaled directly from the source
Its just an opinion
Thanks :)
 

Nibz

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abcde said:
Umm, Nibz, nitrogen is not toxic/poisonous. Otherwise, we'll all be dead breathing 78% of nitrogen in air 24/7! :p

My Bad!
Sorry.
That was supposed to be 'Nitrogen Dioxide'!
 
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WayneRooney10 said:
hey!! Can any one give me a list of all the indicators and how they work? Thanks.

Universal Indicator:

Acid ( Red - Yellow) , Neutral ( Green) , Alkaline ( Blue - Violet)


Phenolphthalein:

Alkaline ( Pink) For Strong ( Colourless) , Neutral ( Colourless) , Acid ( Orange)

Methyl Orange:

Alkaline: ( Yellow) , Neutral ( Colourless) , Acid ( Red)


P.S Some of the indicators have a trend in colour , such as methyl orange from 1-14 colour becomes more pale

Hope that helped,
Thanks
 
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burndtjamb said:
For which substances can potassium dichromate be used as a test for?
To test for the presence of any reducing agent.
 
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TatsuEG said:
WayneRooney10 said:
hey!! Can any one give me a list of all the indicators and how they work? Thanks.

Universal Indicator:

Acid ( Red - Yellow) , Neutral ( Green) , Alkaline ( Blue - Violet)


Phenolphthalein:

Alkaline ( Pink) For Strong ( Colourless) , Neutral ( Colourless) , Acid ( Orange)

Methyl Orange:

Alkaline: ( Yellow) , Neutral ( Colourless) , Acid ( Red)


P.S Some of the indicators have a trend in colour , such as methyl orange from 1-14 colour becomes more pale

Hope that helped,
Thanks

Doesn't phenolphthalein only change colour in alkalis? Isn't it supposed to be colourless in acids? and what about the bromo-something blue? what colour changes does that have? PLEASE HELP!
 
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dancingmaster said:
TatsuEG said:
WayneRooney10 said:
hey!! Can any one give me a list of all the indicators and how they work? Thanks.

Universal Indicator:

Acid ( Red - Yellow) , Neutral ( Green) , Alkaline ( Blue - Violet)


Phenolphthalein:

Alkaline ( Pink) For Strong ( Colourless) , Neutral ( Colourless) , Acid ( Orange)

Methyl Orange:

Alkaline: ( Yellow) , Neutral ( Colourless) , Acid ( Red)


P.S Some of the indicators have a trend in colour , such as methyl orange from 1-14 colour becomes more pale

Hope that helped,
Thanks

Doesn't phenolphthalein only change colour in alkalis? Isn't it supposed to be colourless in acids? and what about the bromo-something blue? what colour changes does that have? PLEASE HELP!

It gives colourless on weak acids


Bromothymol Blue:

Acid (Yellow) , Neutral (Dark green) , Alkaline (Blue)
 
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TatsuEG said:
WayneRooney10 said:
hey!! Can any one give me a list of all the indicators and how they work? Thanks.

Universal Indicator:

Acid ( Red - Yellow) , Neutral ( Green) , Alkaline ( Blue - Violet)


Phenolphthalein:

Alkaline ( Pink) For Strong ( Colourless) , Neutral ( Colourless) , Acid ( Orange)

Methyl Orange:

Alkaline: ( Yellow) , Neutral ( Colourless) , Acid ( Red)


P.S Some of the indicators have a trend in colour , such as methyl orange from 1-14 colour becomes more pale

Hope that helped,
Thanks
Thanks Alot :)
 
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babyzee said:
Tatueg can you take me through one question like exactly how to do it

Very well...

You have been given 3 Aqueous Solutions. K , L , M

L was identified as sodium hydroxide

The first question on the table says

"Ph of L" L is sodium hydroxide which is an alkali

Alkalis have a range of Ph from 8-14 . Sodium hydroxide is a strong alkali so you should provide any ph from the range of 11-14

2nd Question in the table says
What happens if we drop Sodium hydroxide on Copper sulphate

When Sodium hydroxide is added to Copper ion , a Blue precipitate is formed and does not dissolve in Excess of Sodium Hydroxide

Only when Excess ammonia is added , It dissolves giving a Pale blue solution as mentioned in the table


3rd Question in the table says
If Sodium Hydroxide was added to Aluminium Sulphate
Results would be

White precipitate , If in excess would dissolve giving a colourless solution

K is identified as Aqueous Ammonia

and M is identified as Hydrochloric acid duo to acidification and adding silver nitrate and forming a white ppt. which is a typical for a chloride ion test , Donot provide only chloride ion for 2 marks provide a chloride compound such as Hydrochloric acid.
 
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Doesn't phenolphthalein only change colour in alkalis? Isn't it supposed to be colourless in acids? and what about the bromo-something blue? what colour changes does that have? PLEASE HELP![/quote]

It gives colourless on weak acids


Bromothymol Blue:

Acid (Yellow) , Neutral (Dark green) , Alkaline (Blue)[/quote]

Thanks a lot. Just one more question - Does phenolphthalein change colours in strong acids and if it does, what colour change happens?

Again thank you so very much.
 

Nibz

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Math_angel said:
Waalaikumassalam!!

wud like to gie a sugestion...post it as a word doc. as well..with all formatting i mean...it's more easier and better wen u see i wit different kin of colours and formatting and all tat :D

Anyways thanks a lot! Jazak ALlah Khair!! gud work! :)
If only I had time!
You can do that, if possible ! :)
 
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how would i know when to use the right test for water for example :give a test for pure water in the ms they said boiling then the result is 100 but i wrote copper 2 sulphate and its result!! is that correct???thanks
 
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