Birthday Party Fun!

It’s my birthday. That’s right, today I’m celebrating my first birthday! Here are some of my favourite science birthday party experiments for you to try…

You can try these whether or not you’re having a science birthday party!


Children just love slime…I don’t love it myself but seeing their joy makes it all worthwhile!

Step 1: Mix 100 ml of pva glue and ½ teaspoon of bicarbonate of soda

Step 2: Gradually stir in contact lens solution, drop by drop (don’t add too much or it’ll go too hard and make sure it contains sodium borate/ boric acid)

Step 3: When the glue begins to clump together remove from the container and knead until it’s no longer sticky (add a drop or two more contact solution if it’s still a bit sticky)

PVA glue is a polymer, this just means there are lots and lots of molecules linked together in one long line- imagine making a tower out of lego blocks. These polymer chains slide over each other making glue runny and liquid. However, the boric acid or sodium borate in the contact lens solution reacts with the bicarbonate of soda and links the chains together, so instead of flowing over each other they now are all stuck together. This cross linking creates a material we like to call slime! Slime is a non-newtonian fluid, this means the viscosity (thickness) changes when we add or release pressure.

Balloon Bottles

No party would be complete without balloons, but how would you inflate a balloon without using your breath? This simple chemical reaction delights every time.

Step 1: Grab a balloon and a funnel

Step 2: Pop the neck of the balloon over the funnel and drop in a teaspoonful of bicarbonate of soda

Step 3: Carefully remove the balloon from the funnel without tipping out the bicarb!

Step 4: Pour 50ml of vinegar into a plastic bottle

Step: 5: Stretch the neck of the balloon over the bottle without tipping out the bicarb!

Step 6: Lift the balloon allowing the bicarb to tip into the vinegar and let go of the balloon…what happens?

To blow up a balloon you need to fill it up with gas. In this activity we are creating a gas called carbon dioxide by mixing together an acid (vinegar) with a base (bicarbonate of soda). This is a neutralisation reaction, and it is an irreversible change. Once we’ve mixed the vinegar and bicarb together, we no longer have either substance- they have been chemically changed by mixing them


Everyone loves a tasty treat at a birthday party and sherbet is a fabulous one to enjoy because what’s happening is another chemical change.

Step 1: Grab a bowl and a spoon

Step 2: Mix 4 teaspoons of icing sugar, 1 teaspoon of bicarbonate of soda, and 2 teaspoons of citric acid together

Step 3: Taste your sherbet!

When you put the sherbet on your tongue, the saliva in your mouth causes the citric acid to dissolve, it then reacts with the bicarbonate of soda which produces carbon dioxide gas. The carbon dioxide bubbles make the fizzy feeling on your tongue, in fact if you’ve ever had a fizzy drink like Cola or Lemonade, it’s exactly the same as that. Fizzy drinks contain carbon dioxide which is a gas that wants to escape from the liquid, as it does, we see and feel the gas bubbles.

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  1. Summer Holiday STEM » STEM Explorers on July 23, 2021 at 1:31 pm

    […] Rustle up a batch of slime […]

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