Biology

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Video

Materials

• 1 chicken bone
• Vinegar
• 1 drinking glass and plastic wrap, or a jar with a lid

Short explanation

The vinegar dissolves the calcium in the bone, which is what makes bone hard.

Long explanation

The bones of vertebrates like ourselves are more complicated than you might think. A bone is a living tissue with several components. But in short, a bone can be divided into two components; soft connective tissue and hard calcium.

Common household vinegar, also called distilled white vinegar, consists of about 5 % acetic acid and the rest is water. The acetic acid reacts with the calcium in the bone, which leads to it being dissolved in the water. Only the soft connective tissue remains.

An interesting observation can be made before you put the chicken bone in the vinegar. And that is that the bone ends are softer than the rest of the bone. If you are incautious, you may even break the bone ends just by scrubbing. The reason for this is that the bone at the ends is still growing, and there consists of a higher proportion of connective tissue compared to calcium. The calcification of the bone takes place while the bone is maturing.

If you want to save your rubber bone, you need to store it in water (or vinegar), otherwise it will harden.

Experiment

You can turn this demonstration into an experiment. This will make it a better science project. To do that, try answering one of the following questions. The answer to the question will be your hypothesis. Then test the hypothesis by doing the experiment.

• How soft is the bone after 1, 2 or 3 days?
• What happens if you put another type of bone in vinegar?
• What happens if you put the bone in a stronger concentration of acetic acid?

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