Chemistry of the elements

Question 1

How do Group 1 elements react with water

Answer 1

It is used to decipher if an element is part of this family
Lithium, sodium and potassium react vigorously with water, producing an alkaline metal hydroxide solution
It also produces hydrogen gas which is why it fizzes

Question 2

Group 1 reactivity

Answer 2

Elements become more reactive as they go down the group

The elements are more reactive as atomic number increases

Question 3

Periods

Answer 3

the rows of the periodic table, the properties of the elements change as you go along

Question 4

Groups

Answer 4

The columns of the periodic table
The properties of the elements change as you go down the groups
Elements in the same group have similar chemical properties because they have the same number of electrons on their outer shell

Question 5

Group 0

Answer 5

noble gases eg. neon, helium, argon

They are all inert and have a full outer shell

Question 6

Properties of chlorine

Answer 6

Green, gas at room temperature

Question 7

Properties of Bromine

Answer 7

Red brown, liquid at room temperature

Question 8

Properties of Iodine

Answer 8

Dark grey, solid at room temperature

Question 9

Properties of Group 7 elements

Answer 9

They gradually change as you go down the group
atomic number increases
Have a darker colour
Higher boiling point
The higher up the more reactive as the positive cycles has a stronger pull

Question 10

Hydrogen chloride gas dissociates in water

Answer 10

Hydrogen can combine with halogens to form hydrogen halides

When hydrogen chloride is placed in water the molecules split into H+ and Cl- ions

Question 11

Displacement reactions

Answer 11

Redox reactions where the more reactive element “pushes out” the less reactive element from the compound

Question 12

Components of the atmosphere

Answer 12

78% nitrogen
21% oxygen
nearly 1% argon
0.04% C02 and water vapour

Question 13

Copper reaction to find the volume of oxygen in the air

Answer 13

When reacted with the air copper makes copper oxide and uses up oxygen
Using two syringes the markers determine how oxygen has been used up
2Cu + O2 -> 2CuO

Question 14

Iron or Phosphorus to remove oxygen from the air

Answer 14

Use iron wool and acetic acid, place upside down in a beaker of water
Over time the level of water in the test tube will rise because the iron reacts with the oxygen in the air to make iron oxide, the water then rises to fill the space the oxygen took up
White Phosphorous can be used as it smoulders in the air to produce phosphorous oxide

Question 15

Making Oxygen from hydrogen peroxide

Answer 15

The hydrogen peroxide with decompose into water and oxygen
The oxygen is then collected over water using an upside down measuring cylinder delivery tube to collect the bubbles of gas
Or using a gas syringe

Question 16

Burning Magnesium to react with oxygen in the air

Answer 16

Magnesium burns with a bright white flame and forms magnesium oxide which is alkaline

Question 17

Burning Carbon to react with oxygen in the air

Answer 17

It will only burn if heated very strongly

It has an orangey/yellow flame and produces carbon dioxide which is acidic

Question 18

Burning Sulfur to react with oxygen in the air

Answer 18

It burns with a pale blue flame and produces sulfur dioxide which is acidic

Question 19

Producing Carbon dioxide from Calcium carbonate

Answer 19

Marble chips and dilute hydrochloric acid is reacted to form calcium chloride, water and CO2
Collect using downward delivery or a gas syringe

Question 20

Thermal decomposition of metal carbonates

Answer 20

This forms carbon dioxide
Heat metal carbonates, an example of thermal decomposition:
CuCO -> CuO + CO2
then collect using downward delivery

Question 21

Properties of carbon dioxide

Answer 21

Slightly soluble

More dense than air

Question 22

Uses of Carbon dioxide

Answer 22

It is used in carbonated drinks to make them fizz and it dissolves into the drink under pressure and thus produces a slightly acidic solution due to the formation of carbonic acid
It is used in fire extinguishers as it is more dense than air so sinks onto the flames and stops the fire from getting oxygen

Question 23

Production of Acid rain

Answer 23

All rain is slightly acidic because of the solution made when carbon dioxide reacts with water
When sulfur dioxide mixes with clouds it forms sulphuric acid
Nitrogen oxide also forms nitric acid this way

Question 24

Problems caused by acid rain

Answer 24

Kills trees, damages limestone buildings and stone statues

Causes lakes to become acidic thus killing animals

Question 25

Dilute hydrochloric and sulphuric acid with magnesium/ aluminium/zinc/iron

Answer 25

acid + metal > salt + hydrogen
eg. magnesium + hydrochloric acid > magnesium chloride + Hydrogen
Mg + 2HCl > MgCl2 + H2

Question 26

Describe the combustion of hydrogen

Answer 26

Hydrocarbon fuels contain carbon and hydrogen. During combustion, hydrogen is oxidised to water.
In general: hydrocarbon + oxygen → carbon dioxide + water

Question 27

Describe the combustion of anhydrous copper sulfate in the chemical test for water

Answer 27

When it is bound to water it forms blue crystals, heating it will drive the water off
If you want to test for water, add anhydrous copper sulcate and see if the white powder turns blue