In this activity, you will find out how a change in the structure of a molecule can change its physical properties. You will make your own slime by adding contact lens solution and bicarbonate of soda to PVA (school) glue. This is a similar process to how plastic is made, where oil (a liquid) is turned into a solid through a chemical reaction, polymerisation.
To make your slime, you will need three ingredients PVA glue, contact lens solution and baking powder. You can also add some food colouring. You can adjust the units below based on the amount of glue you have.
Squeeze the contents of the glue bottle (100 ml) into a bowl. Add food colouring if desired.
Add and mix in ½ tablespoon of bicarbonate of soda (aka baking soda, but not baking powder) and stir with your stirring utensil.
Mix in 1 tablespoon of contact lens solution with your stirring utensil until combined. You can experiment with the amount of contact lens solution. The more you add, the thicker your mixture will become. The less you add, the slimier it will be. Your contact lens solution must contain boric acid and/or sodium borate for it to activate the mixture, check the ingredients list to be sure.
When your slime begins to pull away from the bowl, you will then need to knead your slime to combine all the ingredients fully.
Once made, keep your slime stored in an airtight container.
So… how was your slime experiment? Are you basically a master alchemist now? We’d love to hear how you got on with this challenge – can you send us a picture or share one on Instagram? Don’t forget to tag us @commonseas so we know where to look, and it’d be great if you could use the hashtag #SeaChampions. Thank you
You can extend the learning for this activity by teaching a full lesson about how plastics are made. For primary school, there is a key stage 2 science lesson What are plastics? Part two and, for secondary school, have a look at the key stage 3 science lesson How are plastics made?.
Play with your slime on a mat or other surface that you don’t mind potential staining.
Wear an apron or old top to make sure you don’t stain clothes.
Keep long hair tied back to avoid getting slimy hair.
If you are posting work on social media, this should be done via a parent, guardian or school account for children under the age of 13. Children over the age of 13 should still be supervised by an adult. Check out the Thinkuknow website for more guidance on online safety.
100ml PVA (school) glue
½ tablespoon bicarbonate of soda (baking soda)
1 tablespoon contact lens solution (must contain either boric acid or sodium borate)
Making slime is a great way to teach students about plastic science as it demonstrates the process of polymerisation before their eyes.
PVA is a polymer, but its chains are relatively short, which is why PVA glue is thick, yet still flows easily.
To explain the chemistry that is going on when you make slime, we have presented a series of particle diagrams below that show the process.
The letters stand for the different elements making up the molecule. H is hydrogen. O is oxygen. C is carbon. B is boron.
This diagram above shows the PVA molecule made up of hydrogen, oxygen and carbon atoms. It forms in chains.
Adding the contact lens solution containing either boric acid or sodium borate changes this. Borate ions are formed (see above).
Borate ions can form weak bonds with hydroxide (O-H) groups found in the PVA molecule. This creates cross-links between the PVA molecules shown using the dashed lines above, forming a web like structure, giving the new substance the properties of a solid.
How is this similar to how plastics are formed?
Plastics start out as a series of smaller molecules too. These are then combined to form longer chains through a process called polymerisation. Once formed, the new substance has different properties to the original.
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