Traditional thermometers measure temperature using mercury, but you can make your own with only water and disinfectant alcohol. Although thermometers of this type cannot be used to check if you have a fever, they can still measure the temperature of the house. With some simple common materials, you can make a fun science experiment that can help you measure the temperature!
Steps
Part 1 of 2: Building the Thermometer
Step 1. Mix 75ml of cold water with 75ml of disinfectant alcohol
Use a measuring cup to mix these two liquids in equal parts. You can mix the solution in the measuring cup or pour it directly into a 500ml plastic water bottle.
- You can buy disinfectant alcohol at the pharmacy.
- Avoid drinking the mixture once you have made it, as it is not drinkable.
Step 2. To make the solution more visible, you can add a few drops of red food coloring
The dye makes the water more similar to the mercury used in traditional thermometers. Pour 1 or 2 drops into the solution and mix it by swirling.
This step is optional if you don't have any food coloring available
Step 3. Put a straw in the bottle so it doesn't touch the bottom
Use a straight, clear straw so you can see the liquid inside. Insert it inside the bottle, fixing it so that it is immersed, but it is important that it reaches a little above the bottom.
If the straw touched the bottom, the water and alcohol solution would not be able to get inside and the thermometer would not work
Step 4. Seal the bottle by sealing the top with clay
Model the clay on the opening of the bottle, so that it does not pass air. Make sure you do not squeeze and do not cover the hole in the straw, otherwise the thermometer will not work. Once all the clay is added, the thermometer will be ready for use.
- You can buy clay at DIY and art stores.
- Alternatively, you can make a hole in the bottle cap that is just large enough to let the straw pass through, then screw it on. Seal all openings with small amounts of clay.
Part 2 of 2: Finding Temperatures
Step 1. Mark the liquid level at room temperature
Look for the level of the solution inside the straw and draw a line on the bottle with a permanent marker. Measure the room temperature with a mercury thermometer to know the actual temperature. Write it down next to the line on the bottle.
Step 2. Place the bottle in a container of hot water and trace the height of the liquid level
Fill the bottom of a container large enough to hold the thermometer with hot water. Put the thermometer in the water and watch the liquid level inside the straw rising. When the level stops, draw a line on the bottle with a marker and mark the actual water temperature.
- The heat causes the expansion of the air inside the bottle. Since the bottle is tightly closed and can only expand through the straw, the water level rises due to this expansion.
- The solution can come out of the top of the straw if the water temperature is too high.
Step 3. Test the thermometer in cold water and mark the temperature on the bottle
Put the bottle in another container with cold tap water. Notice how the solution level in the straw gradually drops. When it stabilizes, mark the actual temperature on the bottle.
- The air contracts as it cools, causing the level of the solution inside the straw to drop.
- The mixture inside the thermometer will freeze below zero and will not work.
Advice
Place the thermometer in various environments to detect temperature differences
Warnings
- DO NOT drink the solution inside the thermometer.
- Avoid squeezing the bottle, otherwise the liquid will come out and may leave stains.
