state the observations

Question 1

dilute HCl is added to copper carbonate

Answer 1

a colourless and odourless gas evolves with a brisk effervescence which turns lime water milky

Question 2

dilute hydrochloric acid is added to sodium thiosulphate

Answer 2

SO2 gas is evolved which turns potassium dichromate paper orange to green

also gives out yellow particles of sulfur

Question 3

calcium hydroxide is heated with ammonium chloride crystals

Answer 3

pungent-smelling ammonia gas is evolved when calcium hydroxide is heated with ammonium chloride crystals

Question 4

when excess sodium hydroxide is added to calcium nitrate

Answer 4

chalky white precipitate insoluble in an excess sodium hydroxide

Question 5

concentrated sulphuric acid is added dropwise to crystals of hydrated copper sulphate

Answer 5

blue hydrated copper sulphate is dehydrated to white anhydrous copper sulphate

sulphuric acid acts as a dehydrating agent

Question 6

a few drops of dilute hydrochloric acid are added to silver nitrate solution followed by the addition of ammonium hydroxide solution

Answer 6

a white precipitate of silver chloride is formed which is soluble in ammonium hydroxide solution.

Question 7

distinguish between sodium nitrate and sodium sulphite using dilute sulphuric acid

Answer 7

add dilute sulphuric acid separately to sodium nitrate and sodium sulfite.

The sodium sulphite will form a colourless gas with a suffocating odour that turns pink acidified potassium permanganate colourless or turns acidified potassium dichromate solution from orange to green

no effect on sodium nitrate