Fireflies, glowsticks, and certain types of glues, paints, and toys are just a few of the things that can glow in the dark. What exactly gives them this special quality? Continue reading to find out more, as well as learn how you can impress your friends and family by making glow-in-the-dark water right at home!
How Do Things Glow in the Dark?
Have you ever been curious about how organisms and objects can light up and grow brightly in the dark? The answer is in the chemicals that they contain! Specifically, there are four terms to describe different ways things can glow in the dark:
Bioluminescence
Fireflies, jellyfish, anglerfish, and glowworms glow because they are bioluminescent. This means they contain natural chemicals that help them glow in the dark for survival tactics such as protection, camouflage, and attracting mates.
Chemiluminescence
Glowsticks are chemiluminescent, meaning that a chemical reaction within them causes them to glow. This is why they glow after the vial is bent and an audible sound is heard. Within the stick, there are a solution of hydrogen peroxide, a solution of phenyl oxalate ester, and fluorescent dye, which are mixed when the stick is bent and react together to cause the colorful bright glow.
Radioluminescence
Some other objects, such as paint, are radioluminscent. These objects contain the element radium which produces low levels of light, which can be seen in the dark.
Phosphorescence
Toys that glow in the dark are described using a different term, phosphorescent. This is because they contain phosphors, which produce light when exposed to radiation, such as heat. This also means they need to absorb that light before having the ability to glow in the dark.
How to Make Glow-in-the-Dark Water at Home!
If you're interested in trying to make your own glow-in-the-dark item to visualize the process of how it works right in front of you, keep reading for a fun at-home experiment to try!
This experiment is from the online STEM website ScienceBuddies, and here are the steps for you to make water glow in the dark! (Warning: because this experiment requires the use of "ultraviolet" black light, please be careful to not look at it directly and have it shine on your skin. It is advised to get an adult to supervise you as you do this experiment, as well as help you handle the bleach!)
The materials you will be needing are:
- Tonic water (water that contains quinine)
- A clear plastic cup
- A medicine dropper
- Bleach
- Ultraviolet "black light" (Although you can buy this from stores, it is simple to make your own! Just color a plastic cling rap with blue marker and put it over a flashlight, color another layer with blue marker and put it over, then color a last layer with purple marker and put it on top, then secure all three layers with a rubber band. You can also use this blue-blue-purple pattern for coloring tape to put over your phone's LED flashlight!)
Procedure:
Pour tonic water into a clear plastic cup.
Make sure your surroundings are dark (turn off any lights) then shine the ultraviolet black light onto the cup of water.
Add 2 drops of bleach into the water using the medicine dropper.
Mix carefully while still shining the black light onto the water.
If there isn't a visible change in the water, keep adding drops of bleach and mixing until you can see it glowing bunder the black light.
By adding bleach into the tonic water, the water will glow blue because tonic water contains a chemical called quinine, which absorbs ultraviolet black light and can produce it afterward. Sound familiar? This process, as referred to earlier, is phosphorescence! The bleach added breaks the chemical bonds in the quinine to perform a reaction that causes the water to release the absorbed black light.
Although trick-or-treating may not be a safe option this year, you can spice up your Halloween with this cool experiment! Happy Halloween and stay safe!
References:
Gillespie, Claire. “How to Make a Homemade Black Light.” Sciencing, Leaf Group Ltd, 12 Nov. 2018, sciencing.com/make-homemade-black-light-7720625.html.
Helmenstine, Anne Marie. “How Do Glowsticks Work?” ThoughtCo, 17 Oct. 2019, www.thoughtco.com/how-do-lightsticks-work-607878.
“How Do Things Glow in the Dark?” Wonderopolis, 18 Oct. 2019, www.wonderopolis.org/wonder/how-do-things-glow-in-the-dark.
Science Buddies. “Explore Glow-in-the-Dark Water! | STEM Activity.” Science Buddies, 10 Jan. 2020, www.sciencebuddies.org/stem-activities/tonic-water-glows.
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