C4.2 Flashcards
How do you know if CO2 is present?
Blow bubbles through the limewater.
If limewater turns cloudy, CO2 is present
How do you know if hydrogen is present?
Hold a burning splint on the mouth of the container with gas.
If it ignites and produces a squeaky pop, hydrogen is present.
How do you know if oxygen is present?
Hold a glowing splint on the mouth of the container with gas.
If it relights then oxygen is present.
How do you know if Chlorine is present?
Hold a blue damp litmus paper on mouth of container.
It will turn red as chlorine is more acidic.
But the final result is litmus paper turns white.
How do you prepare for a flame test?
You use a flame test to test for the cations.
Get a nichrome wire, dip it in dilute HCl and deionised water.
Put it into the Bunsen burner and it should not produce colour.
Then place the wire in the sample of metal compound and put loop into the flame .
A colour should be produced.
What are the results of a flame test?
Lithium - red Sodium - yellow Potassium - lilac Calcium - red/orange Copper - blue/green
How do you do the sodium hydroxide test?
Add few drops of sodium hydroxide solution
If hydroxide precipitate form you can use its colour to determine metal ion.
Copper - blue Iron (II) - green Iron (III) - brown Calcium - white Zinc- white ( if excess NAOH added, it will turn colourless)
How to test for halide ions?
Add dilute nitric acid
Add drops of silver nitrate solution
What are the results of halide ions?
Chlorine - white
Bromine - cream
Iodine - yellow
How to test for carbonates and what are the results produced.
Add barium chloride solution - it will produce a white precipitate of Barium carbonate
Add some dilute HCl
If carbonate present it will fizz to make CO2
Bubble with limewater - cloudy.
How to test for sulfate ions.
Add Barium Chloride solution
Add dilute HCl
If sulfate present white precipitate is formed.
What are the benefits of chemical analysis?
Sensitive
Very Fast
Very Accurate
