Lesson Notes By Weeks and Term v3 - Senior Secondary 1
Water
Download the Lessonotes Mobile Nigeria 2025 app for faster lesson access on Android and iPhone.
Water
Download the Lessonotes Mobile Nigeria 2025 app for faster lesson access on Android and iPhone.
Subject: Chemistry
Class: Senior Secondary 1
Term: 3rd Term
Week: 3
Theme: Chemistry And Environment
This page supports the lesson note with a companion video and a short classroom-ready summary.
For class groups and homework, share this lesson page so learners also get the summary, objectives, and full lesson context.
state sources of Water; state the propertiesof water; Describe the laboratory preparationof water; distinguish betweensoft and hard water; Define pollution and list some waterpollutants; State the uses of water; describe the procedure for the laboratory preparationof water.
Water exists in various forms and locations on Earth. Sources can be broadly categorized as natural and artificial.
Natural Sources: Rainwater: Purest natural form, formed by condensation of atmospheric water vapour. It is naturally soft water.
Seawater: The most abundant source, found in oceans and seas. It is saline (contains dissolved salts like NaCl) and unfit for drinking or agriculture without desalination.
Rivers: Large natural flowing watercourses, usually freshwater, sourced from rainfall or melting snow/glaciers. Examples in Nigeria include River Niger, River Benue, River Kaduna.
Lakes/Ponds: Stagnant bodies of freshwater, fed by rivers, rainfall, or groundwater.
Example: Lake Chad.
Springs: Natural outlets where groundwater flows from the ground.
Wells/Boreholes: Groundwater accessed by digging or drilling into aquifers. These often contain dissolved mineral salts, making the water hard.
Colour: Pure water is colourless. Impurities can give it colour.
Odour: Pure water is odourless.
Taste: Pure water is tasteless.
Boiling Point: 100°C (at standard atmospheric pressure, 760 mmHg or 1 atm). This point is elevated with dissolved impurities.
Freezing Point: 0°C (at standard atmospheric pressure).
Density: Maximum density at 4°C (1 g/cm3 or 1000 kg/m3). Above and below 4°C, its density decreases. This anomaly allows ice to float on water, insulating aquatic life.
Universal Solvent: Water is an excellent solvent due to its polar nature, dissolving many ionic and polar covalent compounds. This is why natural water bodies contain dissolved minerals and gases.
State: Exists as solid (ice), liquid (water), and gas (steam/water vapour) under normal atmospheric conditions.
Neutral pH: Pure water has a pH of 7, meaning it is neutral (neither acidic nor basic). It slightly ionizes into H+ and OH− ions.
Reaction with Metals: Highly reactive metals (Group 1: Na, K) react vigorously with cold water, producing hydrogen gas and metal hydroxides (e.g., 2Na(s) + 2H2O(l) → 2NaOH(aq) + H2(g)). Less reactive metals (e.g., Mg, Zn, Fe) react with steam when heated, producing hydrogen gas and metal oxides (e.g., Mg(s) + H2O(g) → MgO(s) + H2(g)).
Reaction with Non-metals: Can react with some non-metals under specific conditions (e.g., chlorine with water produces hypochlorous acid and hydrochloric acid).
Reaction with Oxides: Acidic oxides (e.g., SO2, CO2) react with water to form acids (e.g., SO2(g) + H2O(l) → H2SO3(aq)). Basic oxides (e.g., Na2O, CaO) react with water to form bases (e.g., CaO(s) + H2O(l) → Ca(OH)2(aq)).
Hydrolysis: Water can react with some salts to produce acidic or basic solutions (e.g., AlCl3 in water is acidic, Na2CO3 in water is basic).
Electrolysis: When acidified water is subjected to electric current, it decomposes into hydrogen and oxygen gases in a 2:1 volume ratio (2H2O(l) → 2H2(g) + O2(g)). Water possesses unique physical and chemical properties crucial for life and its diverse applications.
Community Water Supply and Sanitation (WASH): Application: Students can understand the importance of water treatment processes (e.g., municipal waterworks in Abuja, Lagos) that purify raw water from rivers/boreholes to make it potable. They learn why they shouldn't defecate near water sources (preventing water pollution) and the role of hard water in household chores (e.g., needing more soap for laundry using borehole water in rural areas). This integrates with public health and environmental studies.
Local Context: Discuss community efforts in providing clean water, such as boreholes sunk by NGOs or local governments, and the challenges of maintaining water quality in informal settlements.
Agriculture and Food Security: Application: Water is critical for irrigation in large-scale farming (e.g., rice farming in Kebbi, Kano, or sugarcane plantations). Students understand how water scarcity or pollution can impact crop yield and livestock, directly affecting food supply and the economy.
Local Context: Explain how different farming practices (e.g., fertilizer use) can lead to water pollution (agricultural runoff) and its consequences for downstream communities or aquatic life in rivers like the Benue. Industrial Development and Environmental Impact: Application: Many industries (e.g., breweries like Nigerian Breweries, textile factories in Kaduna, oil refineries in Port Harcourt) heavily rely on water for production, cooling, and cleaning. Students learn about the economic value of water for industries and the environmental responsibility of treating industrial effluents before discharge to prevent pollution.
Local Context: Discuss cases of industrial pollution in Nigeria (e.g., oil spills in the Niger Delta, factory waste discharge into the Lagos Lagoon) and their devastating impact on livelihoods (fishing) and the environment, leading to calls for corporate social responsibility and environmental regulations.