Chemistry of the Environment Flashcards
What colour does anhydrous copper(II) sulfate turn in presence of water?
Blue
What colour does anyhydrous cobalt(II) chloride turn in presence of water?
Pink
Define the term Pure Substance
A pure substance consists of a single element or compound only
Describe the physical test used to determine whether a sample of water is pure
To check the boiling point of water if it is a 100 degrees celsius
Effect of impurities on the boiling point of water
Increase the boiling point
Name the piece of apparatus used to check the boiling point of water
Thermometer
Effect of impurities on the melting point of water
Lower the melting point
Why is distilled water used in practical chemistry?
Due to its high purity, which prevents interference with chemical reactions
List 4 substances that may be found in water from natural sources
- Dissolved Oxygen
- Metal Ions
- Plastic
- Sewage
What are 2 beneficial substances found in water from natural resources?
- Dissolved Oxygen
- Some Metal Compounds
Why is dissolved oxygen beneficial in water?
It is essential for aquatic life
Name 2 potentially harmful substances found in water from natural resources
- Sewage
- Some Metal Compounds
What are nitrates and phosphates in water often sourced from?
Fertilizers & Detergents
True or False?
All metal compounds in water are harmful
False
Define eutrophication
Process where excess nutrients in water promote plant growth, leading to deoxygenation and damage to aquatic life
What is the first step in the purification of water?
Filtration to remove large particles
True or False?
Distillation is used in water purification
False
What happens during sedimentation in water treatment?
Allows heavy particles to settle at the bottom of the water treatment tanks
What is the purpose of Chlorination?
To disinfect water and kill bacteria and pathogens
What type of impurities does untreated water contain?
Soluble and Insoluble Impurities
List 3 examples of soluble impurities in water
- Dissolved Calcium
- Metallic Compounds
- Inorganic Pollutants
What are the 3 main steps of water treatment?
- Filtration
- Sedimentation
- Chlorination
Why is carbon (charcoal) used in water treatment?
To remove unpleasant taste and odors
What does NPK stand for in fertilisers
Nitrogen, Phosphorus, Potassium
What is the role of Nitrogen in plant growth?
Makes chlorophyll and protein, and promotes healthy leaves
How does potassium benefit plants?
Promoting growth, healthy fruit & flowers
What is the main benefit of phosphorus for plants?
Promoting healthy roots
Name 2 common ions that are sources of soluble nitrogen in fertilizers
Nitrate (NO₃-)
Ammonium (NH₄+)
What ion is a source of soluble phosphorus in fertilizers?
Phosphate (PO₄³-)
Name 3 examples of common fertilizer compounds
- Ammonium Nitrate
- Ammonium Phosphate
- Potassium Nitrate
What are the two main gases in the atmosphere?
Nitrogen & Oxygen
What are air pollutants?
Gases present in the atmosphere due to human activity
What is a major source of CO₂ pollution?
Complete combustion of carbon containing fuels
Define Particulates
Small particles of carbon (soot) produced by the incomplete combustion of carbon
State two sources of methane pollution
- Waste Gases
- Decomposing of vegetation
How are oxides of nitrogen formed?
Reaction of nitrogen with oxygen in presence of very high temperatures
What is the main source of Sulfur Dioxide pollution?
Power stations burning fossil fuels containing sulfur compounds
What is acid rain?
Rainwater that has become acidic due to dissolved pollutants
State the equation for the combustion of sulfur to sulfur dioxide
S + O₂ –> SO₂
Define the greenhouse effect
Process where greenhouse gases in the atmosphere absorb and re-emit thermal energy
What are two main greenhouse gases
- Carbon Dioxide
- Methane
What is global warming?
Rise in Earth’s average temperature due to increased concentrations of greenhouse gases in the atmosphere
State two consequences of Global Warming
- Climate Change
- Rise in water levels
Define Climate Change
A long-term change of temperature
How can global warming lead to the spread of diseases?
Creating more suitable climates
What is flue gas desulfurisation
Process used to reduce sulfur dioxide emissions by spraying waste gases from power stations with a slurry of calcium compounds
Define a catalytic converter
Device in a car exhaust that contains transition metal catalysts to render pollutant gases harmless
Describe two reactions that occur in a catalytic converter
- Oxidation of carbon monoxide
- Reduction of oxides of nitrogen
What is the purpose of honeycomb structure in catalytic converters?
To increase surface area for the reaction
State the equation for the reaction of nitrogen monoxide and carbon monoxide in a catalytic converter
2NO + 2CO –> N₂ + 2CO₂
Chemical Formula for Ammonium Sulfate
(NH₄)₂SO₄
What is the term used for a rock that stores water?
An Aquifer
Explain why the combustion of waste crop material should not alter the percentage of CO₂ emitted
The crop removed CO₂ by photosynthesis and combustion returned the CO₂
Explain a reason for an increase in CO₂ emissions
Increased combustion of fossil fuels
State the % of Nitrogen and Oxygen present in the atmosphere
Nitrogen = 78
Oxygen = 21
Which gas is formed in cars and removed using catalytic converters?
Oxides of Nitrogen
Which two gases cause acid rain?
Sulfur Dioxide & Oxides of Nitrogen
