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level: Tests for gases

Questions and Answers List

level questions: Tests for gases

Question	Answer
Place a lighted splint in the hydrogen and air mixture. A squeaky pop is heard.	Hydrogen
Bubble through limewater. Limewater goes from colourless to cloudy/forms a white precipitate.	Carbon Dioxide
Relights a glowing splint.	Oxygen
Damp blue litmus paper turns red then bleaches white.	Chlorine Gas
Damp red litmus paper turns blue.	Ammonia
Blue cobalt chloride paper turns pink.	Water
Identify the stationery phase in the chromatography experiment.	Water (in the paper)
Give a reason why the spots of the food colourings must be above the level of the solvent when the paper is placed in the solvent.	So the solvent will run through the spots.
Give one reason why a spot of food colouring has not moved during the chromatography experiment.	It is insoluble in the solvent they have used.
State one way to make the stationery spot move.	Change the solvent, e.g use water or ethanol.
Neutralises an acid to form a salt	Base
A type of base	Alkali
Give one way to speed the reaction of preparing salts.	Heat up the acid in the water bath.
Give one reason why the copper oxide is added in excess.	So all the acid has turned into the salt and water.
Why is anode smaller	Copper atoms turn into copper ions by losing electrons. Cu --> Cu2+ +2e-.
Why is cathode larger	Copper ions are gaining electrons and turn into copper atoms, Cu2+ + 2e--> Cu. Pure copper is formed
Why does solution remain same shade of blue	For every copper ion discharged from the cathode as the neutral copper atom , a copper ion is released or added to the solution from the anode and so the total number of ions remains the same in the solution. Therefore the blue color of does not fade in electrolytic reaction.
State one way to improve the electrolysis experiment.	Add an ammeter/stick a lightbulb
Electrolyte	A substance that conducts electricity when molten or in an aqueous solution