Home > Chemistry > A Bending Bone

A Bending Bone

By: Suzanne Elvidge BSc (hons), MSc - Updated: 3 Oct 2019 |
Skeleton Bone Endoskeleton Vertebrate

Unless it is something that has a soft and wobbly structure, like a jellyfish, all animals, including humans, have a stiff skeleton to support their muscles and other body tissues, help them move, and protect their internal organs from becoming damaged. Animals with a skeleton inside (known as an ‘endoskeleton’) are called vertebrates, and these include mammals (including humans), birds and fish. Animals with no internal skeleton are called invertebrates. Some of these, including insects and spiders, have a skeleton outside the body, which is called an ‘exoskeleton’.

The skeleton in mammals and birds, and in some fish (known as bony fish), is rigid and is largely made of a mineral called calcium, in a network of other kinds of tissue including cartilage. It has a honeycomb structure, which makes it lightweight. Some fish, including sharks, have a softer skeleton, and these are called cartilaginous fish.

Making a Bone Bend

Take a small bone, such as a chicken drumstick bone, and carefully trim all the meat away (it will taste very good in a sandwich!) Rinse it under warm running water and dry it off. Look at the bone carefully, and gently try bending it. Is it soft or hard? Does it bend? How much does it weigh?

Put the bone in a jar of vinegar and put the lid on. Leave it for one day, dry it off, and weigh it and then try to bend it. Has anything changed? Weigh it and try bending it every day for a week. How has it changed? What do you think has happened to the bone?

Try the experiments again with smaller or larger bones, and with different liquids – what happens if the bone is soaked in water or lemon juice?

What Has Happened?

The main ‘ingredient’ in bones is calcium phosphate, and this makes the bone hard and capable of supporting the body and protecting the organs. After being soaked in the vinegar for a few days the bone should become bendable and flexible. This is because vinegar is an acid (see ‘Acids and Alkalis: Which Are Which?’) The acid in the vinegar reacts with and dissolves the calcium phosphate in the bone. This just leaves the network that surrounds the calcium, which is soft and bendable.

Lemon juice is also an acid, so should also make the bone bendable, but it may take a different length of time. Water is not acidic, so does not dissolve the calcium phosphate – this is a good thing because the human body is 55-78% water (depending on age and size).

Why Is This Important?

This experiment shows that the calcium in bones is important to keep them hard and strong, and so to keep bones healthy, people need to have enough calcium. A lack of calcium can cause a bone disease called osteoporosis, especially in older people, and this makes bones more likely to break. Calcium comes from food, including dairy products, dark green leafy vegetables, seaweed, nuts, seeds and oranges. Vitamin D helps the body absorb calcium – this is also found in dairy products, and is made in the skin in sunlight. A lack of vitamin D can make the bones weak, and can cause a disease called rickets.

You might also like...
Share Your Story, Join the Discussion or Seek Advice..
[Add a Comment]
The bones soaked in water won't change - it's the acid that affects the bones. And eating acid foods doesn't change the pH of the body so won't affect your bones
Suzwriter - 12-Feb-19 @ 6:59 AM
vinegar has acid so if we eat something that contains acid which is bad for bones so what will happen if we eat something that contains Acid!?
asli - 14-Jan-19 @ 5:29 PM
well if it is normal tap water it is a base so nothing will happen unless the water is acidic like from a lake or such
alex - 29-Sep-15 @ 4:07 PM
Do I have to do this same process for a week?
Gracie - 30-Jan-13 @ 12:20 AM
i have a question... what happened to the bones soaked in plain tap water?that's my question....
julie - 31-Jul-12 @ 6:58 AM
Share Your Story, Join the Discussion or Seek Advice...
(never shown)
(never shown)
(never shown)
(never shown)
Enter word:
Latest Comments
  • The Science Guy
    Re: Why Oil and Water Don't Mix
    I’m a 10th grade student and I’m hoping S.O would write a paragraph on how to properly react Al or other metals with HCl or other…
    27 December 2019
  • Sarah
    Re: Making an Emulsion
    i hate airplane food they overheat EVERYTHING
    12 December 2019
  • Delly
    Re: Why Oil and Water Don't Mix
    I’m doing a project and it’s due in two days thanks for the info. I can finally rest after a long day of researching I’m in six…
    10 December 2019
  • Allycat
    Re: Why Oil and Water Don't Mix
    I am doing a fourth grade science project on this.My question is how or do a graph for this.?
    6 December 2019
  • Potent Pickle
    Re: Making an Emulsion
    My chin is very itchy... is it the lava laamp's greatness…
    21 November 2019
  • Timmy Timmy Timmy
    Re: Making an Emulsion
    bruh... what the heck is up with airline food
    21 November 2019
  • Mosey Cook
    Re: Make Yoghurt and Grow Yeast
    This article on natural yeast and good bacteria has been the best read I’ve read on the Internet
    1 November 2019
  • Tee
    Re: Vibrations: Seeing and Feeling Sound
    I have just witnessed a fork vibrating so fast on its own on the kitchen top. It made a sound while vibrating as if the…
    24 August 2019
  • simran panaich
    Re: Soap and Detergent Chemistry
    thnx!! It helped me a lot !!! THank YOu so much
    6 June 2019
  • Mar2
    Re: Why Oil and Water Don't Mix
    I am doing this as a demo for homogeneous mixture examples. It really helps, it is interesting, and thank you so much for it!!!
    5 June 2019