Chemical Tests

holding a burning splint held at the open end of a test tube of gas. If the gas is hydrogen it burns with a loud ‘squeaky pop’

If oxygen is present in a test tube, a glowing splint relights when it is held inside.

If carbon dioxide is bubbled through limewater, the limewater turns milky or cloudy white

Damp litmus paper is bleached white when it is placed in chlorine.

Hold the litmus paper near the mouth of the test tube, damp red litmus paper turns blue

• Dip a clean wire loop into concentrated hydrochloric acid and heat to clean it. Then dip it in the hydrochloric acid again before dipping it into the metal compound that is being tested.

• Hold the loop in the roaring bunsen burner flame

• Use the colour of the flame to identify the metal compound.

blue flame (open the collar so more oxygen can enter), so it will not contaminate the color of the flame

nichrome or platinum as they have high melting point and do not contaminate the color

flame test red

flame test yellow / bright orange

flame test lilac

flame test red

flame test blue-green

sodium hydroxide
warm the mixture
test for ammonia gas

add sodium hydroxide Blue precipitate should form

add sodium hydroxide. green precipitate should form

Add sodium hydroxide brown precipitate should form

add nitric acid, add silver nitrate solution, white precipitate should form

add nitric acid, add silver nitrate solution, cream precipitate should form

add nitric acid, add silver nitrate solution, yellow precipitate should form

add a few drops of barium nitrate solution should form a white precipitate

add hydrochloric acid and bubble through limewater, should turn cloudy

add water to white anhydrous copper (II) sulfate and it turns blue

Using a thermometer check if the boiling point is exactly 100 ^oC

Any impurities present will usually tend to raise the boiling point and depress the melting point of pure substance

To dissolve the compound and remove and carbonate ions, as they would also form a precipitate with the silver ions and so interfere with the test.

calcium hydroxide