S3 Chemistry Acids and Bases

Multiple Choice

Which of the following pH value is basic?

• 2

• 4

• 7

• 9

Multiple Select

Tick the substances that are acidic (You can select more than one answer)

• Tooth paste

• Lime water

• Liquid soap

• Tomato sauce

Multiple Choice

Which of these cannot be used to measure the pH of a substance?

• Universal indicator

• pH paper

• pH meter

• Lime water

​Soluble Non metal Oxides

​What are oxides?

When a substance burns in air it reacts with oxygen to form an oxide.

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https://www.chemedx.org/video/burning-sulfur-produce-sulfur-dioxide

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When sulfur is burned in air it produces sulfur dioxide gas. Sulfur lies at the right hand side of the Periodic Table so it is a non-metal.

 

          sulfur   +   oxygen   →   sulfur dioxide

 Sulfur dioxide dissolves in water to form an acidic solution known as sulfurous acid.

          sulfur dioxide   +   water   →   sulfurous acid

Some text here about the topic of discussion

Carbon dioxide

When carbon dioxide is bubbled through universal indicator solution it turns orange showing that an acidic solution has been produced.

When carbon, a non-metal, burns in air it produces carbon dioxide.

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carbon   +   oxygen   →   carbon dioxide

 

Carbon dioxide is slightly soluble in water, forming an acidic solution.

https://www.youtube.com/watch?v=FXq1nEDsoq0​

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​Nitrogen dioxide

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Nitrogen and oxygen in the air will only react with each other if they are supplied with a lot of energy. They react in lightning storms and also in car engines where there is a high energy spark. The gas produced is nitrogen dioxide which dissolves in water forming an acidic solution.

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https://www.youtube.com/watch?v=UliHodQ6IWI

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​Laboratory Acids

Nitric acid, sulfuric acid and hydrochloric acids are commonly found in the lab.

 

Nitric acid and sulfuric acid are made from non-metal oxides.

 

Hydrochloric acid is made when hydrogen chloride gas is bubbled through water.

Some text here about the topic of discussion

​Acid Rain

https://www.youtube.com/watch?v=WIdWjqZsGgg​

​Read pages 8 , 9 and 10 of your pupils' note and answer these questions orally

Open Ended

Use the internet to answer the following questions.

●     What is the pH of our oceans at the present time?

●     What happens to the pH of our oceans when ocean acidification occurs?

●     What is causing this change in pH?