We have been learning about science this week by playing with eggs.
I was a bit of a science geek at school and even dabbled a bit a university before I settled on my French degree. It is fascinating to me knowing how the world works and I hope I can pass on this awareness to my children. We do experiments because seeing science in action makes the whole thing more understandable. I do explain everything as best I can (without fabrication) so that E knows what is actually taking place. Even if she doesn’t appreciate it fully now the memory will stick with her and the spark of interest is there for later life. It is also just good fun getting to make a mess!
What you will need for our eggsperiments:
- 1 Jam jar
- 1 egg
We started by decorating our jam jars. This is us we talking about – we can’t do anything without decorating first. For this task we used glitter glue and marker pens. There was a general egg theme going on but sometimes E requested stars. Once we had finished with the decorating E filled our jars with vinegar. We had cider vinegar, which wasn’t very strong, meaning we had to change the vinegar for some fresh vinegar half way through. I would suggest using household vinegar instead as it is more acidic and making sure your jar is nice and roomy for your egg so it has plenty to react with. Then we added the eggs and watched them start to bubble as the reaction started.
It is a very simple reaction between the acidic vinegar and the calcium carbonate which is found the shells of bird eggs.
Calcium carbonate (C03) + Acid (H+ ions) -> Water (H2O) + Carbon Dioxide (CO2)
The carbon dioxide is given off as a gas hence the bubbles that form around the egg. If your reaction has stopped due to a lack of acid there will be no more bubbles visible.
We had good fun poking our rather slimy eggs as they fizzed away and turned over and over in the vinegar fuelled by the bubbles. E kept dipping her crackers into the vinegar saying how yummy it was. It took about 2 days for our shells to dissolve completely (changing the vinegar after a day) leaving us with some rather funny looking eggs.
After breaking a couple we had one left which we thought we’d learn about osmosis with. Osmosis is the process by which water passes across a membrane. The membrane that was left around the shell was perfect for this. When the egg was placed in water water diffused through the membrane into the egg which had a higher concentration of salts and sugars (or lower concentration of water). The egg started to expand until it looked like it might burst after only a few hours.
Then we tried the egg in some molasses syrup mixed with a splash of water. The syrup was far more concentrated than the inside of the egg and so the water started to diffuse out of the egg and into the syrup. After 24 hours we had a rather black shrivelled looking egg that we proceeded to prod and poke until it too eggsploded.
What I found really interesting in the molasses egg was that the black of the molasses had also diffused across the membrane into the albumen but not the yolk. Rather the yolk had gone hard and seemingly crystallised. I guess the sugars must have been able to cross over in the opposite direction to the water by active uptake (as to get to that concentration it must have gone against the concentration gradient).
All very simple but good fun. You can choose just to make a mess and explain as little or as much as you want to your children depending on their ages so its good for big brothers or sisters too.