Making our own pH indicators

We often think of pH indicators as chemicals that can only be bought from chemical suppliers In fact, there are natural pH indicators all around us, if we know where to look

Same flowers.. different pH Can you guess which flowers have been grown in alkaline soil and which have been grown in acidic soil?

Making Our Own Indicator copy Juice from… Colour at start Colour with acid Colour with alkali Is this a good indicator? Red cabbage

Indicator from red cabbage Take some chopped red cabbage and put it into a mortar and pestle Add 10ml of water (use a measuring cylinder) Grind up the cabbage Cabbage 10ml of water Mortar and pestle

Filter the cabbage juice

Divide the filtered juice evenly between 2 small beakers Add a small drop of acid to one … And a small drop of alkali to the other Note the results in your table acid alkali

Indicator from flowers Take some flower petals and put them into a mortar and pestle Add a small amount of alcohol Grind flower petals Pour the juice through a strainer Petals ethanol Mortar and pestle ethanol Tea strainer

Divide the strained juice evenly between 2 small beakers Add a small drop of acid to one … And a small drop of alkali to the other Note the results in your table acid alkali

If there is time, repeat the process with different petals or vegetables Which juice do you think makes the best indicator? Why do you think this ?