reactions/tests

Question 1

How do you carry out a flame test?

Answer 1

1. Dip a clean wire loop into the solid compound being tested
2. Put the loop into the blue flame
3. Observe and record colour produced

Question 2

What colour does Lithium give out?

Answer 2

Crimson

Question 3

What colour does Sodium give out?

Answer 3

yellow

Question 4

What colour does Potassium give out?

Answer 4

lilac

Question 5

What colour does Calcium give out?

Answer 5

orange-red

Question 6

What colour does Copper give out?

Answer 6

green

Question 7

What dilute solution is used in metal ion tests?

Answer 7

sodium hydroxide

Question 8

Are metal hydroxides soluble?

Answer 8

No

Question 9

What is the precipitate colour given from Aluminium (Al3) + Sodium hydroxide? And how else do we identify it if excess sodium hydroxide is added?

Answer 9

White
Dissolves to form a colourless solution

Question 10

What is the precipitate colour given from Calcium (Ca2) + Sodium hydroxide?

Answer 10

White
The precipitate is unchanged

Question 11

What is the precipitate colour given from Magnesium (Mg2) + Sodium hydroxide?

Answer 11

White
The solution is unchanged

Question 12

What is the precipitate colour given from Copper (Cu2) + Sodium hydroxide? (this is a transition metal)

Answer 12

Blue

Question 13

What is the precipitate colour given from Iron II (Fe2) + Sodium hydroxide? (this is a transition metal)

Answer 13

Green

Question 14

What is the precipitate colour given from Iron III (Fe3) + Sodium hydroxide? (this is a transition metal)

Answer 14

Brown

Question 15

What is the test for Ammonia, 2NH3?

Answer 15

add sodium hydroxide and warm, a pungent smelling gas (white gas) is formed which turn red litnus paper blue

Question 16

What is the test for a sulfate?

Answer 16

1.add a few drops of dilute hydrochloric to the sample
2.add a few drops of dilute barium chloride or barium nitrate solution
3.a white precipitate forms if sulfate ions are present

Question 17

What is the test for the Group 7 elements?

Answer 17

The silver nitrate test.

Question 18

What is the silver nitrate test?

Answer 18

1. Add acid to sample
2. Add silver nitrate

Question 19

In the silver nitrate test what colour does Chlorine give off?

Answer 19

White

Question 20

In the silver nitrate test what colour does Bromine give off?

Answer 20

Cream

Question 21

In the silver nitrate test what colour does Iodine give off?

Answer 21

Yellow

Question 22

In the reactivity series, when an element is below carbon, how do we separate it?

Answer 22

Displacement

Question 23

In the reactivity series, when an element is above carbon, how do we separate it?

Answer 23

Electrolysis

Question 24

Explain why, in a test for halide ions, dilute hydrochloric acid cannot be used to acidify the sample.

Answer 24

Hydrochloric acid, HCl(aq), contains chloride ions. These would react with silver ions in the test, giving a false positive result.

Question 25

How is calcium oxide/quicklime formed?

Answer 25

calcium carbonate → calcium oxide + carbon dioxide CaCO3(s) → CaO(s) + CO2(g)

Question 26

What happens when water is added to calcium oxide?

Answer 26

calcium oxide + water → calcium hydroxide CaO(s) + H2O(l) → Ca(OH)2(s) The solid remains white but crumbles into a powder as the water is added.

Question 27

What is calcium hydroxide also known as? What is used for?

Answer 27

Slaked lime To neutralise excess acidity

Question 28

Finish this reaction calcium hydroxide + carbon dioxide →

Answer 28

calcium carbonate + water

Question 29

What is the symbol equation for this reaction?

Answer 29

Ca(OH)2(aq) + CO2(g) → CaCO3(s) + H2O(l)

Question 30

How do you test for alcohol?

Answer 30

Add acidified potassium dichromate Positive test: orange-green

Question 31

How do you test for alkene?

Answer 31

Bromine water Positive test: orange-colourless