Traditional thermometers measure temperature using mercury, but can be made at home using only water and rubbing alcohol. While this thermometer can't be used to determine if someone has a fever, it can still tell you the temperature around the house. Using a few simple homemade ingredients, you can create a fun experiment that will help measure temperature!
Step
Part 1 of 2: Assembling a Thermometer
Step 1. Mix 74 ml of cold water with 75 ml of rubbing alcohol
Use a measuring cup to ensure a balanced ratio of water to rubbing alcohol. You can mix the solution in a measuring cup or pour it directly into a 600 ml plastic water bottle.
- You can buy rubbing alcohol at the pharmacy.
- Do not drink this solution after it is made because it is dangerous if consumed.
Step 2. Add a few drops of red food coloring to clarify the liquid
The food coloring will make the solution look like the mercury used in normal thermometers. Pour 1-2 drops of dye into the solution and shake until combined.
This step is optional if you don't have food coloring
Step 3. Insert the straw into the bottle so it doesn't touch the bottom
Use a clear, straight straw so you can see the liquid inside clearly. Place the straw in the opening of the bottle and hold it so that it sinks, but the end of the straw is just above the bottom of the bottle.
If the straw touches the bottom of the bottle, the alcohol solution will not enter the straw and the thermometer will not work
Step 4. Wrap the toy wax around the straw in the eyelet of the bottle to seal it
Work the toy wax in the bottle opening to make it airtight. Make sure the straw is not pinched or the top is covered when setting the candle to allow the thermometer to work. If the candle is in place, your thermometer is done.
- These toy candles can be purchased at a toy store, or an arts and crafts supply store.
- Alternatively, make a hole in the bottle cap that is the right size for the straw and can fit into the bottle. Seal any gaps around the straw and close the bottle with some toy wax.
Part 2 of 2: Measuring Temperature
Step 1. Mark the water level at room temperature
Look at the level of the liquid in the straw and use a permanent marker to draw a line on the bottle. Use a mercury thermometer to measure the room temperature, and record the results. write the measurement results next to the line height of the solution on the bottle.
Step 2. Put the bottle in a container of hot water, and label it
Choose a container large enough to hold your thermometer bottle, and fill it with warm water. Put the bottle in the container, and watch the water level rise in the straw. When the solution has stopped rising, put a marker line on the bottle at the height of the solution with a marker, and write the actual water temperature next to the marking line.
- The heat causes the air in the bottle to expand. Since the bottle is airtight and can only expand through a straw, the water level rises as it expands.
- Water may escape through the top hole of the straw if the water is too hot.
Step 3. Test the thermometer in cold water, and mark the bottle with the temperature
Prepare another container that can hold a bottle, and fill it with cold water. Notice the level of the solution in the straw decreases as it is immersed in cold water. When the solution has not moved, put a mark at that height on the bottle, and write the actual temperature next to the marking line.
- The air shrinks as it cools so the water level drops inside the straw.
- The solution in your thermometer will freeze when the temperature is below 0 degrees Celsius, and will not work.
Tips
Place thermometers in different locations to find the difference in temperature between them
Warning
- Do not drink the solution in the thermometer.
- Avoid squeezing the bottle as the solution inside will splatter and contaminate the room.
