Embark on a journey through the intriguing world of environmental chemistry with Chapter 10 – Chemistry Of The Environment. This comprehensive guide covers essential topics such as chemical tests for the presence of water, the purity of water, substances present in water from natural sources, beneficial and harmful elements in water, and the treatment of domestic water supply. Explore the impact of air pollutants on both human health and the environment, covering pollutants like carbon dioxide, carbon monoxide, methane, oxides of nitrogen, and sulphur dioxide.
Additionally, gain insights into air quality, climate, the composition of clean air, sources of air pollutants, adverse effects, and strategies to reduce environmental issues. Connect the dots between air quality and climate, and discover practical strategies to address climate change, acid rain, and pollution.
1. Chemical Tests for the Presence of Water:
- Anhydrous Cobalt(II) Chloride Test: Anhydrous cobalt(II) chloride paper turns from blue to pink when exposed to water vapour.
- Anhydrous Copper(II) Sulfate Test: Anhydrous copper(II) sulphate turns from white to blue when water is added.
2. Testing Purity of Water using Melting and Boiling Points:
- Melting Point: Pure water freezes and melts at 0°C under standard atmospheric pressure.
- Boiling Point: Pure water boils and condenses at 100°C under standard atmospheric pressure. Deviations from these values can indicate impurities.
3. Use of Distilled Water in Practical Chemistry:
- Reason: Distilled water is preferred over tap water because it contains fewer chemical impurities. The absence of impurities ensures more accurate and reproducible experimental results.
4. Substances Present in Water from Natural Sources:
- Dissolved Oxygen: Essential for aquatic life.
- Metal Compounds: May provide essential minerals for life.
- Plastics: Can be present, harming aquatic life.
- Sewage: Contains harmful microbes causing diseases.
- Harmful Microbes: Pose a health risk.
- Nitrates from Fertilisers: Lead to deoxygenation and damage aquatic life.
- Phosphates from Fertilisers and Detergents: Contribute to water pollution.
5. Beneficial Substances in Water:
- Dissolved Oxygen: Essential for the survival of aquatic life.
- Some Metal Compounds: Provide essential minerals necessary for life.
6. Potentially Harmful Substances in Water:
- Some Metal Compounds: Toxic and harmful.
- Some Plastics: Harm aquatic life.
- Sewage: Contains harmful microbes causing diseases.
- Nitrates and Phosphates: Lead to deoxygenation and damage to aquatic life.
7. Treatment of Domestic Water Supply:
- Sedimentation and Filtration: Remove solid particles.
- Use of Carbon: Removes tastes and odours.
- Chlorination: Kills microbes to ensure water safety for consumption.
GCSE Chemistry – Air Pollution #70
Air Quality And Climate
- Composition of Clean, Dry Air:
- Approximately 78% nitrogen (N₂)
- 21% oxygen (O₂)
- Remainder: Mixture of noble gases and carbon dioxide (CO₂)
- Sources of Air Pollutants:
- Carbon Dioxide (CO₂): Complete combustion of carbon-containing fuels (e.g., coal, oil, natural gas).
- Carbon Monoxide (CO) and Particulates: Incomplete combustion of carbon-containing fuels (e.g., vehicle emissions, industrial processes).
- Methane (CH₄): Decomposition of vegetation and waste gases from digestion in animals.
- Oxides of Nitrogen (NOₓ): Emitted from car engines during combustion.
- Sulphur Dioxide (SO₂): Combustion of fossil fuels containing sulphur compounds.
- Adverse Effects of Air Pollutants:
- Carbon Dioxide (CO₂): Higher levels contribute to increased global warming, leading to climate change.
- Carbon Monoxide (CO): Toxic gas, posing health risks.
- Particulates: Increased risk of respiratory problems and cancer.
- Methane (CH₄): Higher levels contribute to increased global warming, leading to climate change.
- Oxides of Nitrogen (NOₓ): Contribute to acid rain, photochemical smog, and respiratory problems.
- Sulphur Dioxide (SO₂): Contributes to acid rain.
Air pollutants such as carbon dioxide, carbon monoxide, particulates, methane, oxides of nitrogen, and sulphur dioxide have various adverse effects on both human health and the environment. These effects range from respiratory problems to contributing to climate change and acid rain.
Connections between air quality and climate – English – Sept. 2021
Strategies to Reduce Environmental Issues:
- Climate Change:
- Planting Trees: Trees absorb carbon dioxide during photosynthesis, helping to reduce the greenhouse gas effect.
- Reduction in Livestock Farming: Livestock farming, particularly cattle, produces methane. Reducing the demand for meat can lower methane emissions.
- Decreasing Use of Fossil Fuels: Transitioning to cleaner energy sources reduces the release of carbon dioxide from burning fossil fuels.
- Increasing Use of Hydrogen and Renewable Energy: Hydrogen and renewable energy sources like wind and solar power offer cleaner alternatives, reducing dependence on fossil fuels.
- Acid Rain:
- Use of Catalytic Converters in Vehicles: Catalytic converters help reduce emissions of nitrogen oxides, minimising their contribution to acid rain.
- Reducing Emissions of Sulphur Dioxide: Using low-sulphur fuels and employing flue gas desulfurization methods with substances like calcium oxide can decrease sulphur dioxide emissions.
Photosynthesis:
- Definition: Photosynthesis is the process in which carbon dioxide and water react to produce glucose and oxygen in the presence of chlorophyll, utilising light energy.
- Word Equation for Photosynthesis:
Carbon dioxide + Water → Glucose + Oxygen
Explanation of Photosynthesis:
- During photosynthesis, chlorophyll in plant cells captures light energy.
- Carbon dioxide from the air combines with water absorbed by the roots.
- In the presence of light energy, these substances undergo a series of chemical reactions.
- The end products are glucose (a form of stored energy) and oxygen, which is released into the atmosphere.
Implementing strategies to reduce the effects of climate change involves actions like planting trees, transitioning to cleaner energy sources, and reducing meat consumption. Addressing acid rain includes the use of catalytic converters and minimising emissions of sulphur dioxide through various methods. Photosynthesis is a vital process by which plants capture light energy to convert carbon dioxide and water into glucose and oxygen.
How Can We Stop Pollution?
IGCSE Chemistry Note Chapter 11 – Air and water
Summary:
This comprehensive guide on Chapter 10 – Chemistry Of The Environment provides an in-depth exploration of environmental chemistry. From chemical tests for water and assessing water purity to understanding air pollutants and their adverse effects, this guide covers a spectrum of crucial topics. Delve into the composition of clean air, the sources of pollutants, and the detrimental impact on human health and the environment. Connect the threads between air quality and climate, learning about the adverse effects of pollutants like carbon dioxide, methane, and sulphur dioxide.
The guide concludes by offering strategies to mitigate environmental issues, from planting trees to reducing fossil fuel usage and understanding the vital process of photosynthesis. Gain a holistic understanding of the environmental dynamics in preparation for your IGCSE Chemistry exam with this comprehensive guide.
