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Freezing a flower in liquid nitrogen science experiment : Fizzics Education

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Freezing a flower in liquid nitrogen

Freezing a flower in liquid nitrogen

Follow FizzicsEd 150 Science Experiments:

You will need:

NOTHING. Do not try this at home or school unless you have formal training.

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Freezing a flower in liquid nitrogen - materials needed
1 Freezing a flower in liquid nitrogen - pouring liquid nitrogen on the flowers

This experiment works best with large bunches of flowers or large flowers such as a rose or hibiscus. Place the flowers in a tray and carefully pour liquid nitrogen over the flowers. Read the explanation below after watching the short video on liquid nitrogen freezing a flower.

2 A gloved hand holding flowers with fog dropping off them

After cooling the flowers to -196 degrees Celsius, the flowers will retain their shape but are also incredibly brittle.

3 Shattered flowers in a tray with a branch above them

If you give the bunch of flowers a squeeze with a gloved hand, the flower petals will crumble and fall down into the tray!

4 5 student worksheets on flower dissections
5 Fizzics Education making a cloud from liquid nitrogen and hot water at MAAS
6 Teacher showing how to do an experiment outside to a group of kids.

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Why Does This Happen

Liquid nitrogen has a temperature of -196 degrees Celsius. It is so cold that it freezes the water inside the plant cells quite easily. When it has warmed up, the flower becomes quite slimy as some of the cells have broken apart (lysed) and the liquid water inside is able to flow easily. The flower petals have effectively lost their structure. Try this experiment with lettuce leaves or a banana too!

Applications

Freezing flowers using liquid nitrogen is one way that cut flowers can be preserved through freeze-drying. By rapidly cooling the flowers, the ice crystals inside the cells do not get large enough to break the cell walls (thereby retaining the flower structure).  Once the flowers are frozen solid, the moisture within the flowers is then carefully removed using a vacuum pump which causes the solid ice to sublimate into a gas which the vacuum pump then slowly moves to another chamber. Through this technique, the flowers have their water removed so that the colours remain without liquid water inside the plant. A lack of water means that the colours do not degrade due to chemical reactions that are helped by the presence of water. Once the flowers are freeze-dried, they can be returned to normal room temperatures and placed on display!

Classroom activity sheets for this experiment

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5 student worksheets on flower dissections

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Comments

2 thoughts on “Freezing a flower in liquid nitrogen

  1. That is fun looking activity. Freezing a flower in liquid nitrogen looks awesome. I am just wondering if liquid nitrogen can be used to extend the vase life of flowers? I am curious about it now.

    1. Hi Allan!
      We use this demonstration as part of a liquid nitrogen show as it looks fantastic and helps as part of a discussion on cell biology. Freezing flowers using liquid nitrogen is one way that cut flowers can be preserved through freeze-drying… check out the various techniques on this page by the Western Australian government. Once the flowers are frozen, a vacuum pump then removes the moisture slowly so that the flowers will be dry once returned to normal room temperatures. Once done, you can leave the flowers in the vase for much longer than fresh flowers!

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