Chemistry Of Water Module 6 (OCR)

CHEMISTRY OF WATER Module 6  INTRODUCTION Importance of water in sustaining life and regulating Earth's temperature. Water as a "universal solvent" and its applications in industrial, agricultural, and domestic sectors. Renewable energy potential of water (hydropower and ste...

CHEMISTRY OF WATER Module 6  INTRODUCTION Importance of water in sustaining life and regulating Earth's temperature. Water as a "universal solvent" and its applications in industrial, agricultural, and domestic sectors. Renewable energy potential of water (hydropower and steam).  PROPERTIES OF WATER Structure  A water molecule (H₂O) consists of two hydrogen atoms covalently bonded to an oxygen atom.  Covalent Bonds  Ionic Bonds  Metal Bonds  Hydrogen Bonds  PROPERTIES OF WATER Polarity  Water molecule (H₂O) formed by polar covalent bonds, leading to partial positive (H) and negative (O) charges.  Polar - a molecule has regions with slight positive and negative charges due to an uneven distribution of electrons.  PROPERTIES OF WATER Physical Properties  States of Matter: Water exists naturally in three states—solid, liquid, and gas.  Hydrogen Bonding: These bonds give water its high boiling and melting points compared to other similar molecules. PROPERTIES OF WATER State of Water Density Details Solid (ice) 0.9167 g/mL Molecules form a hexagonal crystal lattice, increasing volume and reducing density. Liquid 0.9998 g/mL Liquid water is denser than ice because molecules are more closely packed. Gas (Water ~0.0006 g/mL Highly variable; depends Vapor) on temperature and pressure. PROPERTIES OF WATER Molecular formula 𝑯𝟐 𝑶 Molecular weight 18.0160 g/mol Molecular Geometry Bent, V-shaped Boiling Point 100 °C Freezing Point 0 °C Density 1 g/mL or 1000kg/m3 at 4 °C Polarity Polar pH 7  PROPERTIES OF WATER Key Properties  High Specific Heat: Water can absorb and retain significant heat, stabilizing temperatures in environments.  High Heat of Vaporization: A large amount of energy is needed to convert water to vapor, aiding in cooling mechanisms like sweating.  Adhesion and Cohesion: Adhesion allows water to stick to other surfaces, while cohesion enables water molecules to stick together, facilitating processes like capillary action in plants.  Surface Tension: Cohesive forces create a "skin" on water's surface, allowing small organisms to move across it. A meniscus is the curved surface of a liquid in a container, caused by the liquid's interaction with the container's walls. PROPERTIES OF WATER Properties of Water Value Specific Heat 4.184 J/ g °C Heat of Vaporization 2260 J Molar heat of Vaporization 40.7 KJ/mol  WATER AND ENVIRONMENT: WATER POLLUTION Water Availability:  Only 1% of Earth's water is fresh and accessible.  Saline Water (97%) - Found mostly in oceans, unsuitable for drinking due to high salinity.  Freshwater (2%) - Held in ice caps and glaciers, largely inaccessible.  Available Freshwater (less than 1%) - The small portion accessible for human use.  WATER AND ENVIRONMENT: WATER POLLUTION Causes of Pollution  Chemical contaminants (e.g., pesticides, heavy metals).  Biological pollutants (e.g., E. coli).  Radioactive pollutants (e.g., nuclear waste) Impacts  Health risks, reduced water quality, and ecological damage.  WATER ANALYSIS Temperature Testing  Determines the rate of biochemical reactions and oxygen retention in water. pH Testing  Measures the acidity of water.  Most aquatic life thrives in a pH range of 6 to 8.  WATER ANALYSIS Dissolved Oxygen Test  Measures the amount of oxygen dissolved in water, essential for aquatic life to conduct cellular respiration.. Chloride Test.  Measures chloride levels in water, which may be influenced by minerals and industrial pollution.  WATER ANALYSIS Turbidity Test  Measures the amount of suspended particles in water (water clarity).  High turbidity can impact photosynthesis and increase water temperature Metal Test  Detects harmful heavy metals (e.g., Lead, Mercury, Arsenic, Cadmium) in water  WATER TREATMENT Coagulation  Adding aluminum sulfate (alum) or polymers to water to make particles stick together. Flocs (large particles) are formed and removed by filtration or settling. Sedimentation  Water moves slowly in sedimentation basins, allowing flocs to settle to the bottom.  WATER TREATMENT Filtration  Water passes through filters made of gravel, sand, or activated carbon to remove particles. Disinfection  Adding disinfectants like Chlorine to kill microorganisms and ensure water safety. pH Correction  Lime is added to filtered water to adjust the pH and stabilize soft water. END OF PPT