Scented Balloons

Which scent is which?! Test your friends’ sense of smell with this crazy scented balloon experiment!

Australian Curriculum links

  • Science > Science as a Human Endeavour > Foundation > ACSHE013
  • Science > Science Inquiry Skills > Foundation > ACSIS011

You'll need

  • 3 different scented oils (e.g. rose, peppermint and orange) with their labels covered
  • 3 balloons of different colours
  • 3 eyedroppers

Try this

  1. Use an eyedropper to carefully add a small amount of a scented oil to a balloon. Don’t let any oil drip on the opening in the balloon where you will put your mouth to blow it up.
  2. Inflate the balloon with your mouth or a balloon pump and tie off the balloon.
  3. Repeat steps 1 and 2 to make separate balloons for the two remaining scents.
  4. Smell each balloon and guess their scents.
  5. Have your friends smell the balloons and guess their scents.

What's happening?

Anything that smell (eg. a rose) gives off tiny particles called molecules that are light-weight and float in the air. If some of these molecules reach the inside of our nose, we can sense a smell (eg. the scent of a rose). In this activity, you can smell the scents in the balloons because the molecules that make the scents are small enough to escape through the rubber of the balloon and they float in the air to reach your noses.

The sense of smell, called olfaction, is essential for most animals to survive. Having a sense of smell can help an animal find food, choose a mate, avoid predators and determine their location. Humans have a good sense of smell and are able to detect more than 10,000 different odour molecules. When humans inhale, air enters the mouth and the nose. Inside the nose is a postage stamp-sized area of olfactory receptor neurons. Like a key and a lock, each odour molecule fits only one olfactory receptor. When an odour molecule binds to the olfactory receptor, the olfactory receptor changes shape and creates an electrical signal. The electrical signal travels to the olfactory region of the brain and the brain determines the smell of the odour molecule.

Real world links

The sense of taste is strongly linked with the sense of smell. Seventy to seventy-five percent of what humans perceive as taste comes from the sense of smell. Taste buds allow us to perceive bitter, salty, sour and sweet. When humans eat food, odour molecules from the food travel through the passage from the mouth to the nose and bind with the olfactory receptors.

Astronauts in space tend to lose their sense of smell and taste. Because of the lack of gravity, their sinuses fill up with fluid, causing stuffiness similar to a cold. This prevents their olfactory receptors from binding with the odour molecules. Therefore the astronauts can’t smell or taste their food. On your next trip to the moon, don’t bother planning a gourmet meal or doing the scented balloon test!