Cambridge Secondary (7-9). Stage 7. MCE Science. Workbook - Unit 8: Acids and Alkalis - Question 25

Materials: Safety goggles; gloves; six beakers with 10 cm³ of each of these substances: distilled water, lemon juice, vinegar, liquid soap, fizzy drink (such as cola) and dilute bleach; Universal Indicator paper; white tile; pH chart; Universal Indicator solution in a dropper bottle.

1. Work in pairs or small groups. Put on your safety goggles.
2. Dip a piece of Universal Indicator paper into the substance in each beaker. Use a different piece for each substance.

3. Place the pieces of Universal Indicator paper on a white tile to dry.
4. Match the colour of each piece of Universal Indicator paper to the pH value on the chart. Record this value in the table.
5. Add three drops of Universal Indicator solution to each beaker.


Caution: Universal Indicator solution is flammable. Keep it away from flames. Wipe any spills as soon as they happen. Wash your hands after doing this activity.

Complete the table. Identify whether each substance is acidic, neutral or alkaline. Paste the Universal Indicator paper next to each result.

| Substance | Approximate pH value | Acidic, neutral or alkaline? | Universal Indicator paper |
|:-|:-|:-|:-|
| Distilled water | | | |
| Lemon juice | | | |
| Vinegar | | | |
| Liquid soap | | | |
| Fizzy drink | | | |
| Dilute bleach | | | |