I am trying to do the glow stick science project on science buddies and I am not sure of the directions. Do I get a fresh new glow stick when I add hot water and then another fresh new glow stick when I add the cold water? Or do I keep the same glow stick from start to end by just first measuring room temperature, then add cold water, and then hot water?
[Administrator note: Project directions: https://www.sciencebuddies.org/science- ... glow-stick ]
Glow stick science project
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audreyln
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Re: Glow stick science project
Hello,
This sounds like a fun project! You will use the same glow stick for the measurements with no water, cold water and hot water (steps 1 & 2). After you've done these measurements, you'll repeat with them two more times with two new glow sticks (step 3).
Your question is very intuitive - over time the brightness of the glow stick will decrease as the chemical reaction consumes the reactants inside the glow stick. This would be another variable. That's why it's important to do all steps 1 & 2 together quickly. This experiment assumes that the rate of the chemical reaction is not limited by the reactants in this first 35 minutes (not a variable) and therefore the brightness of the glow stick is unchanged at a constant temperature. If you measure the brightness with no water and cold water and then took a 2-hour break for lunch before testing the hot water your results could be affected.
If you wanted to test for this assumption you could use a new glow stick and measure the brightness with no water for 35 minutes to see if it changes. This would be a good control measurement.
Hope this helps!
Audrey
This sounds like a fun project! You will use the same glow stick for the measurements with no water, cold water and hot water (steps 1 & 2). After you've done these measurements, you'll repeat with them two more times with two new glow sticks (step 3).
Your question is very intuitive - over time the brightness of the glow stick will decrease as the chemical reaction consumes the reactants inside the glow stick. This would be another variable. That's why it's important to do all steps 1 & 2 together quickly. This experiment assumes that the rate of the chemical reaction is not limited by the reactants in this first 35 minutes (not a variable) and therefore the brightness of the glow stick is unchanged at a constant temperature. If you measure the brightness with no water and cold water and then took a 2-hour break for lunch before testing the hot water your results could be affected.
If you wanted to test for this assumption you could use a new glow stick and measure the brightness with no water for 35 minutes to see if it changes. This would be a good control measurement.
Hope this helps!
Audrey