Green sparkles

Copper ions turn a flame green!

Difficulty:
Danger:
Duration:
10 minutes
Experiment's video preview

Reagents

Safety

  • Put on protective gloves and eyewear.
  • Conduct the experiment on the tray.
  • Keep a bowl of water nearby during the experiment.
  • Keep hair and flammable objects away from flame.
General safety rules
  • Do not allow chemicals to come into contact with the eyes or mouth.
  • Keep young children, animals and those not wearing eye protection away from the experimental area.
  • Store this experimental set out of reach of children under 12 years of age.
  • Clean all equipment after use.
  • Make sure that all containers are fully closed and properly stored after use.
  • Ensure that all empty containers are disposed of properly.
  • Do not use any equipment which has not been supplied with the set or recommended in the instructions for use.
  • Do not replace foodstuffs in original container. Dispose of immediately.
General first aid information
  • In case of eye contact: Wash out eye with plenty of water, holding eye open if necessary. Seek immediate medical advice.
  • If swallowed: Wash out mouth with water, drink some fresh water. Do not induce vomiting. Seek immediate medical advice.
  • In case of inhalation: Remove person to fresh air.
  • In case of skin contact and burns: Wash affected area with plenty of water for at least 10 minutes.
  • In case of doubt, seek medical advice without delay. Take the chemical and its container with you.
  • In case of injury always seek medical advice.
Advice for supervising adults
  • The incorrect use of chemicals can cause injury and damage to health. Only carry out those experiments which are listed in the instructions.
  • This experimental set is for use only by children over 12 years.
  • Because children’s abilities vary so much, even within age groups, supervising adults should exercise discretion as to which experiments are suitable and safe for them. The instructions should enable supervisors to assess any experiment to establish its suitability for a particular child.
  • The supervising adult should discuss the warnings and safety information with the child or children before commencing the experiments. Particular attention should be paid to the safe handling of acids, alkalis and flammable liquids.
  • The area surrounding the experiment should be kept clear of any obstructions and away from the storage of food. It should be well lit and ventilated and close to a water supply. A solid table with a heat resistant top should be provided
  • Substances in non-reclosable packaging should be used up (completely) during the course of one experiment, i.e. after opening the package.

FAQ and troubleshooting

Why do I have to dip the wooden stick in water?

Good question! After you get the pieces of copper sulfate on the stick, you coat them with another layer of paraffin to make sure they stay there. Then, you quickly dip the same end of the stick in the beaker of water to help the paraffin cool and acquire the needed consistency.

I mixed up the order in the instructions...

Don’t worry! You can't always get things right on the first try. Try the experiment again.

Step-by-step instructions

Melt some paraffin.

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The copper sulfate CuSO4 crystals will stick to the paraffin.

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Add another layer of paraffin to help the crystals stick better.

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Use water to cool the outer layer.

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Disposal

Dispose of the experiment residues along with regular household trash.

Scientific description

Have you ever wondered how fireworks are made to sparkle with all sorts of colors, like green, red, or pink? The experiment you just performed might give you some valuable clues. Of course, you can't simply "paint" a flame with a colored substance: black coal, brown wood, and white paper all burn with the same yellowish flame. Even in this experiment, your blue copper sulfate CuSO4 tinted the flames green, not blue.

However, there's certainly something to this CuSO4 compound that made the flame green—and this "something" is its copper Cu2+ component. As it turns out, metal ions such as copper ions Cu2+ can emit light of a certain color when heated to high temperatures. Copper emits green , while rubidium Rb creates red , and sodium Na (which is present in table salt NaCl) creates yellow , and so on. In addition to entertaining others with colorful fireworks, chemists use this property of metals to detect which metal is present in a sample by carefully examining the color of the flame using special tools.

In fact, every element in the periodic table has a characteristic "light fingerprint" that is visible under certain conditions. One chemical element was cunning enough to evade chemists' attention on Earth, but couldn't hide its "light fingerprint" in the light of the Sun. Nowadays, this element often attends parties in a balloon costume, and its name is Helium He.

That's interesting!

Colored flame: benefits of beauty

For many years chemists extensively use the capability of some elements to tint a flame in certain colors. Originally, this property was employed to detect these elements in various compounds composition. Back then, researchers evaluated a color and its intensity by eye.

Thanks to progress in modern science, this technique developed into photocolorimetry, a method for precise color characterization. Beyond qualitative analysis, special equipment allows for quantitative characterization of substance composition elements by a flame color. Such data is of great interest to ecologists, geologists, and of course chemists. Unfortunately, this technique only works for certain chemical elements, thus many of them do not tint a flame—not only in visible, but even in ultra-violet spectrum range.