Make an Alka-Seltzer Powered Lava Lamp | STEM activity (2023)

introduction

Have you ever seen a lava lamp? They were the pinnacle of "groovy" room decor of the 1960s. A few minutes after turning on a lava lamp, blobs of colored liquid will float to the top of the lamp and then back down. Make a real lavaLampeConnecting it would take some effort and unusual accessories, but you can create a non-electric version in just minutes using the bubbly power of Alka-Seltzer. In this activity you will learn how to make your own Alka-Seltzer® lava lamp. How does changing the temperature of the ingredients change the behavior of the colorful blobs in your lava lamp?

This activity is not recommended for use as a science fair project.Good science fair projects focus more on controlling variables, making accurate measurements, and analyzing data. To find a science fair project that's just right for you, search our library of over 1,200Science Fair Project Ideasor use theTheme selection wizardto receive a personalized project recommendation.

materials

• Tall identical glasses or bottles, such as 1 liter or 2 liter empty clear plastic bottles (2)
• Messer
• cutting board
• Timer or clock showing seconds
• Water
• food coloring
• vegetable oil (enough to fill the jars almost full)
• An Alka Seltzer tablet. Only one tablet is required for the activity, but it can be fun to have extra tablets if you want to repeat the lava lamp action.
• A way of making one glass hot and one cold, e.g. B. by using a large bowl of hot water and access to a refrigerator or freezer
  

  

What happened?

The ingredients in Alka-Seltzer combine with water to form a gas called carbon dioxide. However, the oil and Alka-Seltzer do not combine in this way. The Alka-Seltzer tablets sink through the vegetable oil until they reach the color water layer. There, the Alka-Seltzer dissolves in the water, forming a gas called carbon dioxide. The gas is lighter than water and oil, so it bubbles up, taking some colored water with it as it moves through the oil layer. You should have seen these bubbles, which look like colorful blobs, floating through the layer of oil to the top of the glass. At the top, the bubbles should have burst (releasing the carbon dioxide gas) and then the colorful blobs should have sunk back down (now with no carbon dioxide gas). The effect is said to have been reminiscent of a lava lamp.

The chemical reaction that leads to the formation of carbon dioxide occurs faster in warmer water. Because of this, you should have seen that the Alka-Seltzer tablet dissolves faster in hot water, around 20-30 seconds depending on the temperature. This should have resulted in lots of fast bubbling and an energetic lava lamp display. In contrast, the Alka-Seltzer tablet should have dissolved more slowly in the cold water, with most of it disappearing in the first two to three minutes, resulting in a calmer and longer-lasting lava lamp effect.

deep ditch

Alka-Seltzer is a drug that acts as a pain reliever and antacid (antacids help neutralize stomach acid like heartburn). The pain reliever used is aspirin and the antacid used is baking soda or sodium bicarbonate. To take the tablets, they are completely dissolved in water, where they are known to undergo a chemical reaction that produces many bubbles of carbon dioxide. Why is this? As the tablets dissolve, the sodium bicarbonate breaks down to form sodium and bicarbonate. The bicarbonate reacts with hydrogen (from citric acid, another ingredient in the tablets) to form carbon dioxide gas (and water). This is how the bubbles form.

How is temperature related to this reaction? In order for the reaction to take place, the bicarbonate has to come into contact with the hydrogen in just the right way. The likelihood of bicarbonate and hydrogen doing this is affected by temperature: the higher the temperature, the faster the molecules move; The lower the temperature, the slower they move. The faster they move, the more likely they come into contact with each other.

For further exploration

• Test Alka-Seltzer tablets in a wider range of temperatures, then record the time it takes for a tablet to dissolve in water at each temperature (check with a thermometer). What temperature change is required to increase the reaction time by a factor of two? How about reducing the response time by a factor of two?
• Compare whole Alka-Seltzer tablets to pieces of Alka-Seltzer tablets. If there is more surface area (i.e. a pill is broken into more pieces), does the same amount of pill make the reaction go faster or slower or some other way?

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