Unit 10 - Chemistry of the environment

Question 1

Cobalt(II) chloride test for water

Answer 1

Dry Cobalt(II) chloride paper will change from blue to pink if exposed to water

Question 2

Copper(II) sulfate test for water

Answer 2

Copper(II) sulfate will change from white to blue if exposed to water

Question 3

How to test for impurities in water

Answer 3

Investigating freezing and boiling points

Question 4

Common substances in water

Answer 4

• Dissolved oxygen - need for aquatic animals
• Metal compounds - needed for plants but can be toxic
• Plastics - harmful for aquatic animals
• Sewage and harmful microbes - can causes diseases
• Nitrates and phosphates from fertilizers - eutrophication

Question 5

Purifying water

Answer 5

• Water from a lake passes through a screen to prevent large solids going through
• Water enters a sedimentation for a while for insoluble heavy solids to fall to the bottom
• Water passes through another filter to remove small insoluble solid impurities
• Water is pushed through carbon particles at high surface area to bond and remove any unwanted molecules that could affect taste and smell
• Chlorine gas is bubbled into the water to kill bacteria and destroy viruses

Question 6

Composition of soil

Answer 6

• 45% mineral
• 5% organic
• 20-30% water
• 20-30% air

Question 7

Purpose of the Haber process

Answer 7

Breaks down diatomic triple-bonded N2 in air to nitrogen that plants can use

Question 8

Composition of NPK fertilizers

Answer 8

• Nitrogen
• Phosphorus
• Potassium

Question 9

Composition of clean dry air

Answer 9

• 78% Nitrogen
• 21% Oxygen
• 1& noble gases - argon (0.93%)
• 0.04% Carbon dioxide

Question 10

Main two gases emitted by humans

Answer 10

• Carbon dioxide
• Methane

Question 11

Greenhouse effect

Answer 11

Increasing concentrations of carbon dioxide and methane molecules in the atmosphere are absorbing some wavelengths of light instead of being reflected which causes the average temperature of the atmosphere to rise

Question 12

Chemicals that cause acid rain

Answer 12

• Oxides of nitrogen
• Sulfur dioxide

Question 13

Particulates

Answer 13

Particles of solid or liquid material that are small enough to remain airborne

Question 14

Reaction taking place in a catalytic converter

Answer 14

• Carbon monoxide + Nitrogen oxide –> Carbon dioxide + Nitrogen
• 2CO + 2NO –> 2CO2 + N2

Question 15

Carbon dioxide source, effects & solutions

Answer 15

• Source - complete combustion of carbon-containing fuels
• Effects - increases global warming
• Solutions - planting more trees, burning less fossil fuels by using renewable energy

Question 16

Carbon monoxide source, effects & solutions

Answer 16

• Source - Incomplete combustion of carbon-containing fuels
• Effects - Toxic gas
• Solutions - Catalytic converters on cars

Question 17

Particulates source, effects & solutions

Answer 17

• Source - burning carbon-containing fuels
• Effects - respiratory problems and increases amounts of cancer
• Solutions - air filters

Question 18

Methane source, effects & solutions

Answer 18

• Source - Decomposition of plants & waste product of animals
• Effects - Increases global warming
• Solutions - Reduce livestock farming & eating less meat and dairy foods

Question 19

Oxides of nitrogen source, effects & solutions

Answer 19

• Source - inside car engines where oxygen and nitrogen react
• Effects - respiratory problems, forms acid rain, produces photochemical smog
• Solutions - Fitting catalytic converters in cars

Question 20

Sulfur dioxide source, effects & solutions

Answer 20

• Source - burning sulfur-containing fossil fuels (coal)
• Effects - forms acid rain
• Solutions - Burning low sulfur fuels instead & flue gas desulfurization by passing gases through solid calcium oxide