Analysis

Question 1

Describe the test for hydrogen

Answer 1

Place a lit splint into a test tube containing the gas, if a squeaky pop accurs the gas contains hydrogen

Question 2

What is the equation for hydrogen combining with oxygen

Answer 2

H2 + O2 -> 2H2O

Question 3

Describe the test for oxygen

Answer 3

Place a glowing splint into the test tube containing the gas, if the splint relight the tube contains oxygen

Question 4

What decomposes to form oxygen and what is the equation

Answer 4

Hydrogen peroxide
2H2O2 —> O2 = 2H2O

Question 5

Describe the test for carbon dioxide

Answer 5

Place the gas in limewater, if limewater turns cloudy it is carbon dioxide

Question 6

How does the limewater turn cloudy

Answer 6

Limewater is a solution of calcium hydroxide so it reacts with carbon dioxide forming a precipitate

Question 7

What is the equation for marble chips reacting with acid forming carbon dioxide

Answer 7

CaCO3 + 2HCl —> CaCl2 + H2O + CO2

Question 8

Describe the test for ammonia

Answer 8

Test the gas with damp red litmus paper, if it turns blue is is ammonia

Question 9

What does ammonium ions reacting with hydroxide ions produce

Answer 9

Ammonia gas which has a pungent smell

Question 10

What is the equation for ammonium reacting with hydroxide

Answer 10

NH4 + OH —> NH3 + H2O

Question 11

What does ammonia produce in water

Answer 11

An alkaline solution

Question 12

Describe the test for chlorine

Answer 12

Test the gas with damp litmus paper, if it become bleached it is chlorine

Question 13

What type of gas is chlorine

Answer 13

Toxic

Question 14

What’s solution is formed when chlorine dissolves in water

Answer 14

Forms an acidic solution

Question 15

What colour is formed by lithium (Li+) in a flame test

Answer 15

Red

Question 16

What colour is formed by sodium (Na+) in a flame test

Answer 16

Yellow

Question 17

What colour is formed by potassium (K+) in a flame test

Answer 17

Lilac

Question 18

What colour is formed by calcium (Ca2+) in a flame test

Answer 18

Orange-red

Question 19

What colour is formed by copper (Cu2+) in a flame test

Answer 19

Blue-green

Question 20

How do you test for ammonium ions using sodium hydroxide

Answer 20

Mix the solution with sodium hydroxide, if ammonium no precipitate is made. Then heat solution and test the gas with damp red litmus paper, if ammonium ammonia gas will be produced and the litmus paper will turn from red to blue

Question 21

How do you test for copper (Cu2+) using sodium hydroxide

Answer 21

Mix the solution with sodium hydroxide, if solution contains copper a blue precipitate will form

Question 22

How do you test for iron (2) (fe2+) using sodium hydroxide

Answer 22

Mix solution with sodium hydroxide, if solution contains iron (2) it will form a green precipitate

Question 23

How do you test for iron (3) (Fe3+) using sodium hydroxide

Answer 23

Mis solution with sodium hydroxide, if solution contains iron (3) it will form a orange-brown precipitate

Question 24

How can you test for the anion chlorine (Cl-)

Answer 24

Mix solution with acidified silver nitrate solution (silver nitrate and nitric acid), if it forms a white precipitate then it contains chlorine

Question 25

How do you test for the anion bromine (Br-)

Answer 25

Mix solution with a acidified silver nitrate solution (silver nitrate and nitric acid), if solution contains bromine it will form a cream precipitate

Question 26

How do you test for the anion Iodine (I-)

Answer 26

Mix solution with acidified silver nitrate solution (silver nitrate and nitric acid), if it forms a yellow precipitate it contains iodine

Question 27

How do you test for the anion sulfate (SO42-)

Answer 27

Mix solution with a acidified barium chloride solution (barium’s chloride and hydrochloric acid), if solution contains sulfate it will form a white precipitate

Question 28

How do you test for carbonate (CO32-)

Answer 28

Mix solution with hydrochloric acid, if CO2 bubble are produce it contains carbonate. To test the bubbles mix with limewater and if it turns cloudy they are CO2

Question 29

What is the first way to test for the presence of water

Answer 29

Test solution with anhydrous copper sulfate, the mixture will turn from white to blue if solution contains water

Question 30

What is the second way to test for the presence of water

Answer 30

Mix solution with cobalt chloride, if solution contains water the mixture will turn from blue to pink

Question 31

What is the first physical test to determine the purity of water

Answer 31

Measure the boiling point of the solution, if it is pure water it will boil at 100°c

Question 32

What is the second physical test to determine the purity of water

Answer 32

Measure the melting point of the solution, in pure water it will melt/freeze at 0°C

Question 33

What is chromatography used for

Answer 33

Separates the mixtures of differently coloured compounds by relying on each substance in the mixture having a different degree of solubility. E.g it can be used to seperate out the different dyes in ink

Question 35

How does chromatography work

Answer 35

The dyes separate as some dyes are more soluble in the solvent, the more soluble the dye the further it travels up the paper

Question 36

What does Rf stand for

Answer 36

Retention factor

Question 37

How do you calculate the retention factor

Answer 37

Rf= distance travelled by solute/distance travelled by solvent

Question 38

What is the solvent

Answer 38

A liquid that dissolves another substance, the solute

Question 39

What is the solute

Answer 39

A substance that is dissolved in the solvent

Question 40

What is the bottom line of a chromatograph called

Answer 40

Baseline

Question 41

Why must h baseline of a chromatograph be drawn in pencil not ink

Answer 41

If it is drawn in ink it will bleed into the inks being tested, contaminating the results and making them inaccurate. Pencil does not do this