Baking soda is a white powder that is frequently used in baking, cooking, and other purposes around the house. You can also use it in some fun experiments, including making crystals. Making baking soda crystals is a fun project, and since you only need a few supplies, the hardest part of the experiment is waiting for them to grow! All you need to have for this experiment is baking soda, water, string, and glass jars.
- 2 cups (450 ml) water
- 1/4 cup (50 g) baking soda
- vegetable coloring (optional)
Part 1 of 3: Make a Baking Soda Solution
Step 1. Boil the water
To make crystals, start by making a solution of water saturated with baking soda. Baking soda dissolves best in warm water. Measure 2 cups (450 ml) of water into a kettle. Turn on the kettle to bring the water to a boil.
Be very careful when using appliances and electronics. Ask a parent, guardian, or adult for help
Step 2. Pour in the water
When the kettle boils, carefully pour the water into a large heat-resistant container, glass, or jar. Be very careful not to spill the water, as it will be very hot and could burn you. It is better if you ask an adult to pour it.
Step 3. Add the baking soda
Pour half of the baking soda into the jar of hot water. Stir the mixture to dissolve it in the water. Then add the remaining baking soda 1 teaspoon at a time, stirring each time to dissolve.
- Keep adding baking soda until it no longer dissolves in the water and a thin layer of powder forms on the bottom of the jar.
- You may need to add a little more than 1/4 cup (55 g) of baking soda or less to fully saturate the water.
Step 4. Chill and divide the water
When the water no longer absorbs the baking soda, set it aside for about 20 minutes to cool. When the solution has cooled, divide it evenly into two small jars or glasses.
Leave some of the solution in the original bottle and discard the undissolved baking soda that remained at the bottom
Step 5. Separate the jars
Select a flat surface where you can leave the jars untouched for about a week. Some good places include a workbench or countertop. Place the jars on the table or counter about 6 inches (15 cm) apart. Place a plate between the jars to catch any dripping water.
It will take several days for the crystals to grow and you shouldn't move them once they start. That is why it is important to find a place where you can place the experiment
Step 6. Color the water
If you want the crystals to be colored, you can add five to 10 drops of food coloring to each jar. Stir the solution to blend the color. You can put the same color in both jars, or color each solution a different color.
If you put different colors in each jar, half of the crystals will be one color and the other half will be another
Step 7. Cut a piece of string
Baking soda crystals need a medium in which to form, and string is ideal. You can use any type of fabric rope, such as rope, twine, or wool. Use scissors to cut a 1 foot (30 cm) long string.
Be very careful whenever you use scissors, and make sure you have adult supervision when cutting or using sharp tools
Step 8. Attach weights to the rope
To keep the strings in the baking soda solution, you can tie weights to each end. You can use beads or clips as weights. Thread each end of the string through a hole in a bead or the end of a paperclip and tie a small knot to secure it.
Step 9. Place one end of the string in each jar of water
Take one end of the rope and carefully drop the weight into one of the jars. Drop the other end of the rope with the weight into the other jar. The string between the two jars should be loose and hanging slightly, in the shape of a smile.
Part 2 of 3: Observe How Crystals Form
Step 1. Leave the jars undisturbed for several days
Baking soda crystals form when the solution saturates the string and the water evaporates. When the water evaporates, there will be crystals of baking soda. You can watch the experiment anytime you want, but don't stir the water or touch the string.
The crystals take between five and seven days to fully form
Step 2. Take notes on the growth that occurs every day
To find out how fast the crystals are growing, watch the experiment at the same time every day. Each day, take note of any changes that have occurred since the previous day. You can document the experiment as follows:
- Take notes on the length and thickness of the crystals.
- Look at the water level in the jars.
- Draw pictures of the experiment.
- Take pictures of the project.
Step 3. Take out the string and dry the crystals
After about five days, when the crystals have formed, you can remove the rope. Grab the rope with both hands where it joins the jars. Carefully remove the string with the crystals from the jars and place it on a clean plate. Let the rope dry for several hours.
Part 3 of 3: Get Creative with Crystals
Step 1. Create stalactites and stalagmites
Stalactites and stalagmites are mineral deposits that frequently form within caves. You can see how they form if you add more water to the string when you create the crystals:
- Every day, scoop out a tablespoon of the baking soda solution from one of the jars.
- Spray a few drops of the solution in the center of the string to saturate it.
- As the water drips onto the dish below and evaporates, deposits of baking soda crystals will form that hang from the center of the string (stalactites) and grow from the dish below (stalagmites).
Step 2. Make them in egg shells
Scoop a few drops of the colored baking soda solution into the middle of a clean eggshell. Stir the water to cover the inside of the shell. Place the egg on a plate and set it aside for a day or two to allow the water to evaporate. Each day, add a few more drops of water. As the water evaporates, crystals will form inside the eggshell.
Step 3. Make different types of crystals
You can also make other types of crystals using the same method that you used to make the baking soda crystals. Other types of crystals you can make include sugar, salt, and Epsom salt. Use the following method to make these types of crystals:
- Dissolve 2/3 cup (135 g) of sugar, salt, or Epsom salt in a glass of hot water.
- Divide the solution between two jars.
- Cut a 1 foot (30 cm) piece of string.
- Place each end of the string in one of the jars.
- Leave the experiment for several days for the crystals to form.