CLASS: 3rd – 6th    +1 hour     SESE (SCIENCE)

Curriculum Links - Mixing and Changing

  • Chemistry - pH scale, acidic and base solutions

Learning Objectives - WALT (We are learning to…)

  • The pH scale!
  • Basic and Acidic liquids
  • How liquids behave

Teaching Methodologies

  • Active Learning – Hands on experimental work
  • Recording - Analysing work and results
  • Skills through content – Predicting and observing

Introduction

Scientists use a scale called the pH scale to measure how acidic or basic something is. The scale runs from 0 to 14. Where 0 is the most acidic and 14 is the most basic. Around the middle we have neutral liquids, like water!

Things we use to test if something is acidic or basic are called indicators, as they indicate where something sits on the pH scale. Indicators change colour when they come into contact with the test solution. The colour will tell us how acidic or basic it is!

Here we are going to test a variety of different liquids to see if they are acidic or basic. Using red cabbage as an indicator! It is good practice to follow the scientific process during this experiment, making predictions before testing each liquid and then recording results.

Get help!

The cabbage must be boiled in water to make the indicator solution. Ask an adult to boil the cabbage and save the water. Allow it to cool before pouring in a bottle and using for the experiment

Experiment

Shopping List!

  • Red Cabbage
  • Water
  • Plastic Bottle
  • Some glasses or cups
  • Spoon for mixing
  • Vinegar, baking soda, lemon juice, wood cleaner, washing up powder, shampoo.

Once we have the indicator solution ready we canbegin the experiment. Make sure you have the pH scale eitherprinted out or on a computer (if using a computer, keep it far away from the liquids).

First lets test water. Pour some water into a cup and mix in some of your cabbage indicator solution. Make a note of what colour it turns. What does this tell us about its pH? Is it acidic, neutral or basic?

Next lets try lemon juice. Before adding in the indicator make a prediction as to what colour you think it will turn to based on the pH scale.

Keep repeating this with the different liquids you have. For the dry mixtures, like baking soda and washing up powder, dissolve them in water before testing with the cabbage indicator.

Line up your results and compare them to the pH scale. How did they turn out and what did you learn?

There are lots of acidic and basic substances in our bodies. Acids in our stomach and bases in the pancreas help with digestion