Imaginative Teaching Resources & Inspirational Career Ideas from the Chilled Food Industry
Some of us are coming out of lockdown and getting back to the classroom, and some of us are still at home. Whatever your situation is these easy food science experiments make learning fun.
Morgan and Tilly spent a couple of hours trying them out. They’re both at primary school. If your child is a similar age during their usual science classes they’re likely to be thinking about the changes explored in these experiments.
This is a dramatic chemical reaction guaranteed to get a dramatic audience reaction! But don’t worry – it’s all completely safe and uses everyday store cupboard items.
First you need to locate some bicarbonate of soda, washing up liquid, food colouring and lemon juice.
Put teaspoon of bicarb into a tall narrow cup or glass. Add a squirt of washing up liquid. Add a drop of food colouring and use a spoon or straw to mix it all together.
Squeeze or pour in small amount of lemon juice – stir whilst you pour.
Watch the bubbles form and fill the cup – add more lemon juice and bicarb to make it froth over the top!
So, what’s happening here?
Bicarbonate of soda, when mixed with lemon juice, forms carbon dioxide gas bubbles and as these are released they bubble in the washing up liquid it creates soapy bubbles.
What’s the science?
This is the formation of a new substance, a gas, by mixing two substances together. It’s the evolution of a gas and a chemical change – solid + liquid forms gas.
We all know how quickly cola disappears, especially on a hot day! But this experiment will make it
vanish before your eyes.
For this you need just three things – cola, milk and a clean jam jar.
Fill the jam jar ¾ full with cola, add a small amount of milk into the jar.
Screw the top onto the jar. Careful – don’t shake it up!
Place it on a level surface and leave it for 20 – 30 minutes.
What’s happened? Nothing? Leave it a bit longer.
After a while the milk will settle to the bottom of the jar in a lumpy brown gunge
(that’s a technical term 😊).
You’ll see the rest of the liquid is completely clear!
What’s happened here?
Phosphoric acid molecules, which contain the cola’s brown colour, attach themselves to the milk’s molecules at the first chance they get. The milk, laden with the phosphoric acid molecules, curdles into lumps, which are much heavier than other liquids in the drink. These sink to the bottom, taking the phosphoric acid (and the brown colour) with them – leaving lighter clear liquids that are left over to float to the top.
Now for the science…
This is demonstrating density of liquids and solids formed from liquids – called precipitates. The reaction of phosphoric acid with the calcium contained in the milk gives rise to a precipitate (the lumpy brown gunge) which is dense and the liquids separate out.
We all need a balanced diet with calcium for our bones. If we don’t have enough calcium in our diet we could end up with bendy bones!
For this experiment you’ll need a bone – if you’re having a roast dinner then a chicken one works really well, a clean jam jar and some vinegar.
Wash and clean the bone thoroughly to get rid of any meat.
Tap the bone and make sure its solid – how does it feel? Hard to the touch isn’t it?
Place the bone in the jam jar, fill the jar with vinegar till the bone is covered – screw on the lid.
Leave the jar and bone for ¾ day – take the bone out and rinse in water
Try to bend the bone – what happens? Surprising isn’t it?
Why has the bone gone bendy?
Calcium gives bones their strength, the acid in the vinegar is mild but enough to dissolve all the bone’s calcium molecules – so that all that is left is the pliable bone tissue.
How to keep your bones strong and healthy, not weak and bendy
Make sure you eat calcium-rich food – there’s a good choice including milk, cheese and other dairy foods, green leafy vegetables such as broccoli, cabbage and okra (but not spinach), soya beans, tofu, bread and anything with fortified flour. Fish with bones you eat such as sardines and pilchards.