Reactions- Topic 2

Question 1

give the composition of air, their percentages and uses.

Answer 1

OXYGEN- 21%, used for welding torches, breathing apparatus, rocket fuel.
NITROGEN-78%, used for food preservation, electronics,
ARGON-0.9%, used for welding.
CARBON DIOXIDE-0.04%, use for fizzy drinks, fire extinguisher.
ALL OTHER (water and pollutants)- 0.06%

Question 2

what is air a mixture of?

Answer 2

nitrogen, oxygen, carbon dioxide, noble gases + water vapour.

Question 3

What are the properties of nitrogen?

Answer 3

colourless, odourless, less dense (lighter) than air

Question 4

what are the properties of argon?

Answer 4

Colourless, odourless, gas at room temp, denser(heavier) than air.

Question 5

What are the properties of oxygen?

Answer 5

Colourless, odourless, gas at room temp, slightly soluble in water, same density as air.

Question 6

What are the properties of carbon dioxide?

Answer 6

colourless,odourless, gas.

Question 7

What are the uses of oxygen?

Answer 7

breathing apparatus (hospital, fire brigade etc), rocket fuel, welding.

Question 8

Give the equation for the preparation of oxygen.

Answer 8

hydrogen peroxide —> water + oxygen

Question 9

What chemicals are required for preparation of oxygen?

Answer 9

Hydrogen peroxide, manganese dioxide catalyst.

Question 10

What is the test for oxygen?

Answer 10

Glowing splint will relight.

Question 11

What is a catalyst?

Answer 11

Chemical that speed up a reaction without being used up itself,
E.g platinum, iron.

Question 12

What is an enzyme?

Answer 12

Soluble protein molecules. Speed up chemical reactions in cells.
(BIOLOGICAL CATALYSTS)
e.g DNA replication, digestion, protein synthesis.

Question 13

name some reactions of oxygen. (Oxidation reactions)

Answer 13

respiration equation, rusting equation, burning a fuel equation.

Question 14

what is the word equation for respiration?

Answer 14

sugar + oxygen —> carbon dioxide + water (energy)

Question 15

what is the word equation for rusting?

Answer 15

iron+ oxygen+ water —> hydrated iron oxide

Question 16

what is the word equation for burning a fuel?

Answer 16

Fuel + oxygen—> carbon dioxide + water (+energy)

Question 17

What is the chemical test for water?

Answer 17

Anhydrous copper sulfate goes from white to blue.

Question 18

what is combustion?

Answer 18

when a fuel reacts with oxygen to release useful energy. (Process of burning something)

Question 19

what are the uses of hydrogen?

Answer 19

making margarine, clean fuel, rocket fuel.

Question 20

what is the word equation for preparing hydrogen?

Answer 20

magnesium + hydrochloride acid —> magnesium chloride + hydrogen

Question 21

what chemicals are required for the preparation of hydrogen?

Answer 21

magnesium, hydrochloric acid.
(Can be prepared by acid with a metal)

Question 22

What is the test for hydrogen?

Answer 22

lighted splint will make a squeaky pop you can hear.

Question 23

What are the uses of carbon dioxide?

Answer 23

fizzy drinks, fire extinguisher, dry ice.

Question 24

What is the word equation for preparing carbon dioxide?

Answer 24

calcium carbonate + hydrochloric acid —> calcium chloride + water + carbon dioxide.

Question 25

what chemicals are required for the preparation of carbon dioxide?

Answer 25

Hydrochloric acid, marble chips (calcium carbonate) Can be prepared easily by reacting a metal carbonate with an acid.

Question 26

What is the test for carbon dioxide?

Answer 26

Bubble gas into limewater. Positive result turns limewater from colourless to milky white/cloudy.

Question 27

What happens if too much carbon dioxide is bubbled into limewater?

Answer 27

If lots added solution becomes clear again as soluble calcium hydrogen carbonate forms.

Question 28

What happens when calcium carbonate is added to hydrochloric acid?

Answer 28

Fizzing of gas and solid disappears.

Question 29

using the gases hydrogen, oxygen and carbon dioxide decide if each is less dense than air

Answer 29

hydrogen= yes oxygen= no carbon dioxide=no

Question 30

using the gases hydrogen, oxygen and carbon dioxide decide if each has upward delivery.

Answer 30

hydrogen= yes oxygen=no carbon dioxide=no

Question 31

using the gases hydrogen, oxygen, carbon dioxide decide if each is denser than air.

Answer 31

hydrogen=no oxygen=slightly carbon dioxide=yes

Question 32

Using the gases hydrogen, oxygen and carbon dioxide, decide if each uses downward delivery.

Answer 32

hydrogen=no oxygen=no carbon dioxide=yes

Question 33

using the gases hydrogen, oxygen and carbon dioxide decide if each’s solubility in water (high or low)

Answer 33

hydrogen= very low oxygen= low Carbon dioxide= low

Question 34

using the gases hydrogen, oxygen and carbon dioxide decide each’s solubility overwater

Answer 34

hydrogen=yes oxygen=yes carbon dioxide=yes

Question 35

given the gases oxygen, hydrogen and carbon dioxide state the test and result for each.

Answer 35

OXYGEN test- glowing splint. result- relights. HYDROGEN test- lighted splint. Result-squeaky pop. CARBON DIOXIDE test- bubble into limewater. result- limewater turns milky.