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KS3 Chemistry

KS3 Chemistry. 7E Acids and Alkalis. Contents. 7E Acids and Alkalis. What are acids and alkalis?. Hazard symbols. Indicators and the pH scale. Neutralization. Summary activities. What is an acid?. Acids are a group of chemicals.

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KS3 Chemistry

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  1. KS3 Chemistry 7EAcidsandAlkalis

  2. Contents 7E Acids and Alkalis What are acids and alkalis? Hazard symbols Indicators and the pH scale Neutralization Summaryactivities

  3. What is an acid? Acids are a group of chemicals. What do you know about acids? Are all acids dangerous?

  4. What is an acid? Acids are a group of chemicals. Which of these items contains an acid? laboratory acids everyday acids Can you think of other examples of acids?

  5. What is a weak acid? Acids are found in household items such as food, drink and beauty/skincare products. It is safe to handle these acids and even taste them, if they are for eating! These acids are known weak acids.

  6. What is a strong acid? Some acids, like those found in the laboratory or a car battery, are very dangerous (too dangerous to taste or touch). These acids are said to be corrosive as they can damage other materials by wearing them away!They are strong acids. Why must strong acids always be handled very carefully?

  7. What is an alkali? Alkalis are another group of chemicals, the opposite of acids. Which of these items contains an alkali? everyday alkalis laboratory alkalis Can you think of other examples of alkalis?

  8. What is a weak alkali? Alkalis are found in soaps and other materials used for cleaning. It is safe to handle these alkalis, which can feel soapy. These alkalis are known as weak alkalis.

  9. What is a strong alkali? Some alkalis, like those in the laboratory or in cleaning materials such as toilet cleaner, are too dangerous to touch. These alkalis are said to be caustic because they can burn skin and damage other materials! They are strong alkalis. Why must strong alkalis always be handled very carefully?

  10. Contents 7E Acids and Alkalis What are acids and alkalis? Hazard symbols Indicators and the pH scale Neutralization Summaryactivities

  11. What are hazard symbols? How can you tell which chemicals are safe and which are dangerous? Special symbols are used on bottles and vehicles that contain dangerous chemicals. corrosive toxic irritant harmful highly flammable These hazard symbols show why the chemical is dangerous. Why is it important that these symbols can be recognised by people from other countries?

  12. What do hazard symbols mean?

  13. Contents 7E Acids and Alkalis What are acids and alkalis? Hazard symbols Indicators and the pH scale Neutralization Summaryactivities

  14. What is an indicator? How can you test a liquid to find if it is an acid or an alkali? An indicator is a special chemical that changes to a different colour in an acid or an alkali. Litmus paper and litmus solution are examples of indicators. Litmus is red in acid. Litmus is blue in alkali.

  15. Litmus test experiment

  16. What is universal indicator? Litmus is used to show if a solution is acid or alkali. Litmus does not show if the acid or alkali is weak or strong. Universal indicator has a range of colours that show how weak or strong the acid or alkali is. strongeracid stronger alkali strongacid weak alkali weakacid strongalkali neutral What is the colour for a weak acid? What is the colour for a strong alkali?

  17. What is the pH scale? The strength of an acid or alkali is measured by the pH scale. Each universal indicatorcolour is given a number called the pH value. Universal indicator can tell you the pH of a solution. strongeracid stronger alkali 1 2 3 4 5 6 7 8 9 10 1112 1314 strongacid weak alkali weakacid strongalkali neutral What is the pH of a weak acid? What is the pH of strong alkali?

  18. What is the pH?

  19. Are these substances acidic or alkaline? Are they weak or strong? What type of substance? 1 2 3 4 5 6 7 8 9 10 11 12 13 14 acid alkali very weak acid very strong acid very weak alkali weak alkali strong acid very strong alkali weak acid

  20. Contents 7E Acids and Alkalis What are acids and alkalis? Hazard symbols Indicators and the pH scale Neutralization Summaryactivities

  21. Mixing an acid and an alkali What happens when an acid and an alkali are mixed? ? Mixing an acid and an alkali causes a chemical change. This chemical change is called a chemical reaction. How do you know this chemical reaction has taken place?

  22. What is neutralization? The chemical reaction betweenan acidandan alkali is calledneutralization. acid alkali a salt water What happens to the pH value of the reaction mixture during neutralization? The pH value of the reaction mixture becomes closer to 7.

  23. What is neutralization? The chemical reaction between anan acidandan alkalican be written as: acid alkali a salt water What are the two new substances produced by a neutralization reaction?

  24. Neutralization and indigestion

  25. Neutralizing stings A beesting isacidic. A wasp sting isalkaline. Why can bicarbonate of soda (pH 9) be used to treat a bee sting? Why can vinegar (pH 3) be used to treat a wasp sting?

  26. Neutralizing soil Soils in different places can be acidic, alkaline or neutral. Many plants do not grow well in acidic soil. Why do farmers test soil to check the pH? Farmers often add an alkali to acidic soil to make their plants grow better. How does the alkali help to treat the acidic soil?

  27. Neutralizing acid rain Gases emitted by cars, power stations and factories mix with rainwater in the atmosphere. This rainwater has a pH <5.5. Why is it called acid rain? Acid rain can have a harmful effect on the environment killing trees, polluting lakes and damaging buildings. How can the effects of acid rain be prevented?

  28. Contents 7E Acids and Alkalis What are acids and alkalis? Hazard symbols Indicators and the pH scale Neutralization Summary activities

  29. Glossary • acid –A chemical that has a pH less than 7. • alkali –A chemical that has a pH greater than 7 and dissolves in water. • indicator –A special chemical that changes into different colours in acid and alkali solutions. • neutral –A chemical with a pH of 7 that is not an acid or an alkali. • neutralization –The chemical reaction between an acid and an alkali. • pH scale – The range of values that shows how strong or weak an acid or alkali is. • universal indicator – The indicator that shows the pH value of a chemical.

  30. Anagrams

  31. Word search

  32. Weak acids, like lemon juice and vinegar, taste sour. Strong acids are corrosive and can “eat away” at metal, stone and flesh! Acids turns blue litmus paper red. Acids have a pH of less than 7. Acids can be neutralized with alkalis. Facts about acids

  33. Alkalis feel soapy and are used in household cleaning materials. Strong alkalis are caustic. Alkalis turn red litmus paper blue. Alkalis have a pH of more than 7. Alkalis can be neutralized with acids. Facts about alkalis

  34. Multiple-choice quiz

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