Final answer:
Calcium sulfate controls the setting rate of alginate by reacting with sodium alginate to form a gel. The amount of calcium sulfate determines the setting time, allowing customization for different applications.
Step-by-step explanation:
The compound that controls the setting rate of alginate is called calcium sulfate. Alginate, typically used in dental impressions and as a food additive, is a material that gels when mixed with water due to the reaction between sodium alginate and calcium ions. The setting time can be manipulated by varying the amount of calcium sulfate in the mixture. A higher concentration of calcium sulfate accelerates the setting process, while a lower concentration slows it down. Therefore, dentists and other professionals can control the setting rate according to the requirement of the procedure being performed.