OCR Gateway GCSE Chemistry A Predicting and identifying reactions and products (C4) overview quiz quiz

Iron displaces copper: the blue colour fades and copper coats the nail

Nothing happens at all, because iron is much less reactive than the copper

The iron simply dissolves away into the solution with no other change at all

Copper from the solution displaces the iron straight out of the metal nail

Iron is more reactive than carbon, which is the whole reason carbon is able to reduce its oxide so easily

Aluminium has no ore anywhere on Earth from which it could ever possibly be extracted at all

Iron is less reactive than carbon, so carbon can reduce it, while aluminium is more reactive than carbon

Carbon can only ever work to extract the very light metals and never any of the heavier ones at all

Yellow

Crimson

Green

Lilac

Iron(III)

Copper(II)

Iron(II)

Calcium

A lighted splint gives a squeaky pop

A glowing splint is relit

It turns limewater cloudy

It bleaches damp litmus paper

Add some silver nitrate solution and look for a precipitate

Add barium chloride solution and watch for a white precipitate

Add a dilute acid and test the gas with limewater

Carry out a flame test and observe the colour of the flame

A white precipitate

A pale cream precipitate

A blue precipitate

Yellow

To remove carbonate ions, which would give a false positive precipitate

To speed up the whole reaction so that the test gives a result faster

To deliberately change the final colour of the precipitate that forms

To help dissolve the silver nitrate fully before it is added to the sample

1.33

0.75

0.48

14

They are always far cheaper to carry out than any simple chemical test

They need no special equipment at all and can be done anywhere quickly

They are more sensitive and can detect very small amounts

They give a colour change that you judge by eye, just like the simple tests