Friday activities
Welcome to Friday! I hope you've had lots of fun this week investigating different scientific concepts and experiments. Just because 'Science Week' is ending, that doesn't mean you stop learning about Science. Don't forget, you can bookmark my website and keep coming back to watch the videos and try the experiments over and over again!
The last two experiments I have for you today are a safe version of Elephant's toothpaste you can do at home and making Oobleck. Lots of messy fun in store!
I have also shared my footage of the Big Watermelon Experiment! Check it out again!
Apparatus needed for today's experiments:
1/2 cup hydrogen peroxide - 3% solution will work, 6% solution makes for a faster reaction
dried yeast
warm water
dishwashing detergent
food colour
empty 600mL bottle
2 cups cornflour
1 cup water
bowl
Elephant's toothpaste experiment - do elephants even use toothpaste I wonder...?
First up today is a safe version of Elephant's Toothpaste you can try at home. It makes a bit of a mess but it is a fast acting chemical reaction that is fun to create!
Elephant's toothpaste is an exothermic (heat-generating) chemical reaction made using hydrogen peroxide, yeast, dishwashing detergent and food colouring.
The 'take 1' video was my first attempt at making it. I learned that making it in a smaller bottle produces a better effect! So how does it work? Hydrogen peroxide is made of two parts hydrogen and two parts oxygen (H2O2) and is a highly reactive chemical. The yeast acts as a catalyst on the hydrogen peroxide, causing it to be broken down into water (H2O) and oxygen gas (O2).
This reaction generates heat (exothermic) as the chemical bonds in the hydrogen peroxide are broken. The dishwashing detergent captures the released oxygen and creates bubbles, which makes the detergent foamy. This allows us to see the oxygen being released. The food colouring just makes it look colourful!
I performed the elephant's toothpaste experiment a second time - with much better results I think!
This time I used two different strengths of hydrogen peroxide to compare the reaction - a 3% solution and a 6% solution. I also used only the 600mL bottles to show the reaction to greater effect. Check it out! The 6% solution worked faster than the 3% and definitely looked better as it reacted!
2. Making Oobleck
Oobleck is a simple to make fluid that will bring you hours of fun to play with! You just need 2 parts cornflour (sometimes called cornstarch) to 1 part water! Mix them together with your hands and have fun playing!
Oobleck is a "non-Newtonian" fluid; it has properties of both liquids and solids. You can slowly dip your hand into it like a liquid, but if you squeeze the oobleck or punch it, it will feel solid. This happens because the relatively large solid cornstarch molecules form long chains. The smaller water molecules flow past each other and between cornstarch molecules allowing the chains to slide and flow around each other. This is why oobleck behaves like a liquid when it is not under pressure. But when pressure or force is applied, the water molecules are squeezed out of the gaps between the cornstarch molecules, making them lock together and therefore act like a solid!
Oobleck actually gets its name from a Dr Suess book 'Bartholomew and the Oobleck' where a gooey green substance, Oobleck, fell from the sky and wreaked havoc in the kingdom. Hopefully your oobleck doesn't wreak havoc at your house!
