How to grow baking soda crystals？
MATERIALS FOR BAKING SODA CRYSTALS
Clean jar or glass
Weight (e.g., paperclip)
Pencil or butter knife (to hold the string over the glass)
PREPARE THE CRYSTAL CONTAINER
You want to hang the string in the glass or jar so that it doesn't touch the sides or bottom of the container.
Tie the string to the pencil or knife, weight it so it will hang straight, and adjust the length of the string so that it doesn't touch the bottom of the container.
PREPARE THE CRYSTAL SOLUTION
Mix as much baking soda as you can into just-boiled water. For 1 cup of water, this is approximately 7 teaspoons of baking soda. Add the baking soda a little at a time, stirring between additions, because carbon dioxide gas will be evolved, causing the solution to bubble initially. Alternatively, heat baking soda and cool water until it is near-boiling. Allow the solution to sit undisturbed for a few moments to allow any undissolved baking soda to sink to the bottom of the cup.
GROW BAKING SODA CRYSTALS
Pour the baking soda solution into the container. Avoid getting undissolved baking soda in the glass.
You may wish to cover the container with a coffee filter or paper towel to keep the solution clean while permitting evaporation.
Allow the crystals to grow as long as you like. If you start to see a lot of crystal growth on the sides of the container rather than on your string, pour the remaining solution into a new container. Transfer your string to the new container to get better growth.
When you are satisfied with your crystals you can remove them from the solution and allow them to dry.