Natural Sciences and Technology Grade 6 Term 2: Matter and Materials Mixtures and Water resources

Topic 5 Mixtures and Water resources Water pollution Gr 6 Natural Sciences and Technology – Term 2, Topic 5

Water Water covers over 70% of the Earth’s surface. Pure water is made up of just two elements: hydrogen and oxygen. Pure water is colourless, tasteless, and odourless. Insoluble substances can be mixed in water. Soluble substances can be dissolved in water. Gr 6 Natural Sciences and Technology – Term 2, Topic 5

Insoluble substances in water Do you remember the definition of insoluble substances? Insoluble substances are solids that cannot dissolve in a solvent. There are certain substances that are insoluble in water. Gr 6 Natural Sciences and Technology – Term 2, Topic 5

Insoluble substances in water Some insoluble substances are found naturally in water: Dust particles Sand Rocks Gr 6 Natural Sciences and Technology – Term 2, Topic 5

Insoluble substances in water Some insoluble substances are put in water by people. These are harmful to fish, plants, and animals that need water to survive: Oil Plastic Gr 6 Natural Sciences and Technology – Term 2, Topic 5

Soluble substances in water Do you remember the definition of soluble substances? Soluble substances can dissolve in a solvent. There are many substances that are soluble in water. Gr 6 Natural Sciences and Technology – Term 2, Topic 5

Soluble substances in water Some soluble substances are found naturally in water: Gasses (e.g. oxygen, nitrogen & phosphorus) Minerals salts (these dissolve quickly) Dead vegetable and animal matter (these decay and dissolve slowly) Gr 6 Natural Sciences and Technology – Term 2, Topic 5

Soluble substances in water Some soluble substances are put in water by people. These are harmful to fish, plants, animal that need water to survive: Soap Insecticides Gr 6 Natural Sciences and Technology – Term 2, Topic 5

Soluble substances in water Water is a good solvent. Water dissolves most things that it comes into contact with, including poisonous substances like fertilizers. This is why water from water tanks, rivers, wells, and dams can easily become polluted (contaminated). Polluted water is harmful to the fish and plants and animals that need that water to live. Gr 6 Natural Sciences and Technology – Term 2, Topic 5

What is Water Pollution? Water pollution happens when substances are put into water which are harmful to the fish, plants and animals that need safe water to survive. Water pollution most often happens because of the actions of people. Water can be polluted by: insoluble substances – such as plastics, glass, oil and tins, soluble substances – such as soaps, fertilizers, insecticides, acids and poisonous chemicals, living germs – from toilet waste which cause illnesses such as diarrhoea. Gr 6 Natural Sciences and Technology – Term 2, Topic 5

Water pollutants INSOLUBLE pollutants – You can see these with the naked eye: Plastic bags, tyres, containers, oil, etc. SOLUBLE pollutants – You often cannot see these with the naked eye: fertilizer, pesticides, soap, detergents, liquid waste, etc. GERMS – You cannot see these with the naked eye, but essentially it is carried by human waste and cause diseases e.g. diarrhoea and cholera. Gr 6 Natural Sciences and Technology – Term 2, Topic 5

Water pollution Water pollution affects the drinking water, rivers, lakes and oceans all over the world. In many developing countries Water pollution is a leading cause of death, because people drink from polluted water sources Water pollution is caused by untreated waste water flowing into rivers, lakes and coastal waters Gr 6 Natural Sciences and Technology – Term 2, Topic 5

The impact of an oil spill Gr 6 Natural Sciences and Technology – Term 2, Topic 5

Water pollution Water pollution is the second biggest environmental concern along with air pollution. Gr 6 Natural Sciences and Technology – Term 2, Topic 5