1. KS 3 laboratory Indicators De Lisle Catholic Science College Science department

2. Litmus indicatorRed cabbage indicator Universal indicatorLitmus indicator problem Virtual laboratory: Indicators menu

3. Litmus colour changes Acids turn: – blue litmus red Alkalis turn: – red litmus blue blue litmus paper red litmus paper Add to acid Add to alkali

4. Red cabbage indicator Acids turn: – purple RC red Alkalis turn: – purple RC green purple RC paper Add to acid Add to alkali

5. Universal indicator Acids turn universal indicator: yellow, orange or red Neutral solutions turn universal indicator:green Alkalis turn universal indicator: blue/green, blue or purple

6. Universal indicator advantages universal indicator can indicate the strengths of acids and alkali solutions –i.e. it can indicate pH values

7. Colour changes with universal indicator pH7 pH1 pH14 NeutralAcidAlkali Add universal indicator

8. Type of liquidUI colourpH value Strong acid Medium acid Weak acid Neutral Weak alkali Medium alkali Strong alkali Red Yellow Orange Green Blue/green Blue Purple 1- 3 4 -5 6 7 8 9 -10 11- 14

9. Litmus paper problem Liquid ALiquid B neutral (pH 7) weak acid (pH 6) What can we infer from the observations? Add universal indicator to both liquids Add a piece of blue litmus paper to both liquids

10. KS 3 laboratory De Lisle Catholic Science College Exit Thank you for your visit to our virtual laboratory