activity 15: Bendy Bones Here we'll tell you how chicken bones can be tied into knots! All you need is a little help from some simple household ingredients… You'll need: 1 large jar or glass Some small, long, thin chicken bones, washed and clean Vinegar What to do: Put the chicken bones in the jar or glass and pour in enough vinegar to cover them. Leave them somewhere safe for 5-7 days. Remove the bones from the jar and try bending them.What happens? You're now ready to practice your bone-bending, knot-tying technique! Once you've finished playing, tie the bones up into a tangle (or arrage them into a pattern of your choice) and leave them out to dry. You can fix them in place using pins or adhesive if necessary. After a few days they'll go hard again, leaving them permanently bent. Whats happening! You probably know that bones contain calcium. This is found in the form of calcium carbonate, which helps give bones their hardness. When you put the bones into the vinegar, which is a weak acid, the calcium carbonate starts to react with it. You can even see the reaction taking place- if you observe the bones at regular intervals when they're submerged, you'll see small bubbles forming on their surface. These are bubbles of carbon dioxide gas, formed as the calcium carbonate breaks down. Without it, the bones become much softer and are less rigid than before. Hey presto- bendy bones! But leaving the soft bones out in the air for a while allows them to harden again- they'll react with carbon dioxide in the air to regain some of their hardness.
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