T2T5 Mixtures and water Natural Science Gr.6 2015

KEY WORDS Rate of dissolving Speed at which something dissolves. Factor A change that effects the result of an experiment. Respiration breathing. Aquatic plants Plants that grow in and around water. Fertilizers Chemicals added to the soil to improve the quality or size of plants.

Water pollution (Copy) Natural substances mix with fresh water or dissolve in it, for example: Oxygen (O2) Carbon dioxide (CO2) Nitrogen dioxide (NO2) Minerals

1. Oxygen (O2) It dissolves in the water, in order for aquatic animals to use it for respiration (breathing). 2. Carbon dioxide (CO2) Carbon dioxide dissolves in the water in order for aquatic plant to use it during photosynthesis.

3. Nitrogen dioxide (NO2) One of two natural gasses (the other one is CO2) that can dissolve in rain water and make it acidic. It forms when nitrogen gas combines with oxygen gas in the air. This happens when lightning flashes. It then dissolves in the rain water and falls to the ground. It provides nitrogen to the soil that promotes healthy plant growth.

4. Minerals Some minerals dissolve in water and flow down rivers and streams. This is why drinking water from a stream is healthier than rain water.

Polluting substances in water (Copy) Sweet water Meaning of Amanzimtoti: Sweet water refers to the quality and taste of clean water sources. Some streams still have sweet water, but the fresh water in many of our dams and rivers are polluted.

Water can be polluted by: (Copy) Insoluble substances oil, plastic, tyres, tin, glass, etc. Soluble substances Soap, fertilizers, insecticides, acids and other poisons. Living germs from toilet waste, that cause water-borne diseases such as diarrhoea.

Date:________ Name:_______ Assessment Give the definition of Amanzimtoti. Where would we find aquatic plants? Name 4 natural substances that dissolve in water. Write the chemical formula for oxygen. Write the chemical formula for carbon dioxide. Give 2 examples of insoluble substances that pollute our rivers. Give 2 examples of soluble substances that pollute our rivers. Name a water-borne disease caused by living germs from toilet waste, that pollute our rivers.

Give the definition of Amanzimtoti. Assessment (MEMO) Give the definition of Amanzimtoti. Sweet water. Where would we find aquatic plants? In water. Name 4 natural substances that dissolve in water. Oxygen, Nitrogen dioxide, Carbon dioxide and Minerals. Write the chemical formula for oxygen. O2

Write the chemical formula for carbon dioxide. CO2 Give 2 examples of insoluble substances that pollute our rivers. (any 2) Give 2 examples of soluble substances that pollute our rivers. Name a water-borne disease caused by living germs from toilet waste, that pollute our rivers. Diarrhoea.

Fertilizers pollute streams and rivers by speeding up the growth of algae and hyacinths. Because of the fertilizers these plants grow so well, that they cover the whole water surface. No sunlight can reach the other aquatic plants, causing them to die. This leads to the death of the fish, due to a lack of oxygen.

Algae

Algae

Algae

Hyacinths

Hyacinths

Hyacinths

2. Over-active growth of algae and hyacinths 1. Fertilizers in water 4. No sunlight to other aquatic plants 3. Algae and hyacinths cover water surface 5. No oxygen in water 6. Fish die

Unnecessary activities that pollute our water. (Copy) People leave rubbish lying around. Insoluble substances dumped by uncaring contractors. Careless farmers use too much fertilisers and insecticides on their crops. When it rains these chemicals wash down into the streams.

Farm animals and people live near water sources Farm animals and people live near water sources. Their faeces are dumped into the rivers causing water-borne diseases. Factories illegally dump soluble pollutants.

WATER POLLUTION

WATER POLLUTION

WATER POLLUTION

WATER POLLUTION

WATER POLLUTION

WATER POLLUTION

WATER POLLUTION

Wetlands (Copy) What is a wetland? Marshy area that is water logged. It is lower than surrounding areas. Rainwater and rivers run into it. Lots of reeds and sedges grow in it. The water cannot always be seen.

SEDGES

SEDGES

REEDS

REEDS

REEDS

It is a biodiverse region (habitat for many different plants and animals). Rural areas depend on it for drinking water. Reeds can be used to build shelters and craft products. Tourists visit these areas, thus creating jobs.

WETLANDS

WETLANDS

WETLANDS

WETLANDS

Class activity.

Wetlands remove soluble and insoluble substances from water Rivers run through wetlands. Reeds in wetlands trap insoluble substances that flow in rivers. Special bacteria in water logged soil change soluble pollutants into harmless substances. Dirty water that flows into a wetland, comes out clean on the other side. Therefore wetlands are very important.

Wetlands act like sponges. Sedges and reeds slow rivers down after heavy rains, thus preventing flood damage. They store water for droughts. During heavy rains excess water is stored in the soil. Throughout the dry period this water slowly leaves the ground and flows back into the river.

Scientists compare wetlands to sponges, because they store water during wet periods and release it when it is dry. Therefore wetlands regulate the flow of water.

Homework activity NS: -Mind map Topic 5 (term 2)