Water, Water, Water!
Water is the most precious resource on this planet...even more precious than gold. Water is a simple covalent molecule that boils at 100 degrees and freezes at 0 degrees, if it is pure. Read through this tackk and complete all of the activities in your book. There is also a short quiz at the end for you to complete and submit. Your teacher will receive your answers.
The following diagram shows the covalent bonding in water. Each covalent bond is a shared pair of electrons. Water has a low melting and boiling point because there are weak intermolecular forces between the molecules that require little energy to overcome.
Testing for water.
In the lab there are two ways in which we can test for the presence of water. Firstly, we can use blue cobalt chloride paper and secondly we can use anhydrous copper sulfate. Look at the pictures below. In your book, write down how we can use these two substances to test for water. Make sure you write down the change that happens!
Water is needed for lots of things! Make a copy of the mind map below and write down what water is used for in each setting. Think of as many examples as you can!
Where does water come from?
In many places, our water supply is pumped from rivers. Some is pumped up from below the ground, where water that has drained down through the soil lies trapped in rocks. This underground water is called groundwater. It is held in rock called aquifer – like a sponge!
This water is not clean, even if it looks it! There will be mud, animal waste, bits of dead vegetation....but worst of all, there will be microbes! Drinking dirty water can cause diarrhoea and diseases such as cholera and typhoid. Let's look to see how water can be cleaned anywhere!
A modern treatment plant
Make a copy of the diagram above which shows a modern water treatment plant. Then, put the statements (below) in order to show how particles are removed and microbes are killed to ensure our water is safe to drink.
However, the water might still have harmful substances in it, such as nitrates. Nitrates can make babies ill. Think: How might nitrates end up in the water? These dissolved substances can be removed using special membranes but it is very expensive.
And, you're done!
Scroll back up to ensure you have completed all of the necessary tasks in your book.
Now, answer the questions in the quiz below. You can only submit your answers once and your teacher will receive a copy of your responses.