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Indicators - year 7 - Cambridge standards
- 1. H.W in workbookpages 103 to 108 Due Sunday 26th of January
- 2. Check H.W in workbookpages 89 to 97
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- 4. Each container hasacid, alkali or water. The three containers look the same. How can we tell them apart?
- 5. Indicator An indicator isa substance that changes colour to distinguish between acids and alkali acid alkali neutral
- 6. Red cabbage juicecan be used as an indicator
- 7. Red cabbage indicatorturns red in acids, blue in water and yellow in alkalis. So, you now know what was in each beaker
- 8. What is anindicator? Litmus is a commonly used indicator. It can be added to filter paper, or used as a liquid. acid alkali neutral
- 9. Neutral Acid Alkali Litmus solution+ acid red Litmus solution + alkali blue Litmus solution + Neutral purple Litmus solution
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- 11. Complete the table Redlitmus colour Blue litmus colour (alkali) (acid) (neutral)
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- 17. • Litmus justshow if a substance is an acid or an alkali • Litmus paper cannot distinguish between a weak acid and a strong acid Or weak alkali and strong alkali. • A better indicator is required…
- 18. Universal indicator Universal indicatorcan change into many different colours. It shows how weak or strong the acid or alkali is.
- 19. pH scale The strengthof an acid or alkali is measured by the pH scale. Each universal indicator colour is given a number called the pH scale. Universal indicator can tell you the pH of a solution.
- 21. pH Classification 0 -2 Strong acid 3 - 6 Weak acid 7 Neutral 8 - 11 Weak alkali 12 - 14 Strong alkali Red – yellow – green – blue – purple
- 22. Are these substancesacidic or alkaline? Are they weak or strong? 1 2 14 13 12 11 10 9 8 7 6 5 4 3 Substance pH Description of acid/base soda water 6 car battery acid 1 soap 8 washing soda 10 stomach acid 2 oven cleaner 14 vinegar 4 weak acid strong acid weak alkali weak alkali strong acid strong alkali weak acid alkal i aci d What type of substance?
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- 25. WB page 104 Toprotect eyes from splashes. Not to spill anything on yourself Not to get the chemical on the work surface. So that you are less likely to have a spill if you knock the bottle over. To less likely mix up what you are doing and use the wrong chemical.
- 26. W.B page 106 Achemical that shows how acidic or alkaline a substance is.
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- 28. W.B page 107 1-Cut up some coloured plant such as red cabbage or beetroot and place it in the mortar; 2- Crush it using the pestle; 3- Add some ethanol and crush it some more; 4- remove some of the liquid using the pipette and place it in a test tube.
- 29. W.B page 107 1)Place a little acid in a test tube and little alkali in another test tube. 2) Add few drops of the indicator. 3) If your indicator works there will be different colours in the acid and the alkali.
- 30. W.B page 107 Thecoffee or cola will stain it a darker colour, so you will not be able to decide if it is an acid or an alkali.
- 31. Solve in pastpaper