PLEASE HELPPPP AS chemistry practical.....!!

[OhGosh]

For the second part of the question.. about the testing things.
I DON'T UNDERSTAND HOW YOU TEST FOR GASES....!!!
what if yu do a test, gas is released and you have to test for it but the gas is already gone?
And some of them take too long! and you only one chance.
Will they provide with all the materials for every single gas test?
and most important! how do you know which gas is released!!? if you don't know one of the reactants

 

[MAVtKnmJ]

You should have asked your teacher these questions long ago and not on the last day of the exam lol

Anyways I will try to be as accurate as possible:

1) When they ask you to add a Reagent e.g HCL then in most cases they are requiring you to identify an acidic gas e.g out of these three: NO2, CO2, SO2

If you see Brown color in the test tube then it's NO2, if you see/hear effervescence then it's CO2 and if none of these two then obviously it's SO2.

2) In most cases where Hydrogen or Oxygen is released, they won't ask you to add a Reagent HCL, instead they will tell you to add the compound/powder/crystals in a boiling test tube and heat it. You will put your hand/lid on-top of the test tube (this is called collecting the gas) in these cases to collect the gas and then perform the "Glowing Splinter" or "Burnt out Splinter" tests to confirm the gases.

3) In most cases when NH3 is released, they will tell you to add the compound/powder/crystals in a boiling test tube and add little NaOH to it and then boil it gently. To test for NH3 we will hold a damn red litmus paper on-top of the test tube and see if it turns blue. If it doesn't then NH3 gas is absent. Then they will tell you to repeat this step but add Aluminium foil into the test tube and then re-heat the tube. We will test with red litmus paper again and this time it will turn blue, therefore NH3 gas. This will prove that this compound contains Nitrate or Nitrite. You can differentiate between a Nitrate and a Nitrite by adding dilute HCL.

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No they won't put out all the material required for the gas tests on your table, it's your duty to ask them for the required material i.e litmus papers, splinters, etc.

I hope this helps