Final answer:
Plaster of Paris, made of calcium sulfate hemihydrate, and dental stone, a harder version of plaster, are used for casts in medical applications and dental molds due to their quick setting and hardening properties.
Step-by-step explanation:
Plaster of Paris and dental stone are examples of materials that have a variety of uses in the medical and dental industries. Plaster of Paris is a common name for calcium sulfate hemihydrate (CaSO4·rac{1}{2}H2O), which is used to make casts for broken bones. When mixed with water, it hardens quickly, making it ideal for creating a hard, stable structure to immobilize broken limbs. Dental stone is a harder version of plaster that is used in dentistry to create precise molds for dental work. Both of these materials are derived from calcium sulfate dihydrate (gypsum), with plaster of Paris being heated to lose some of its water content and become a hemihydrate. These compounds are valuable for their properties in creating molds and casts in health and dental care.