A sample consisting of 22.7 g of a nongaseous, unstable compound X is placed inside a metal cylinder with a radius of 8.00 cm, and a piston is carefully placed on the surface of the compound so that, for all practicla purposes, the distance between the bottom of the cylinder and the piston is zero. (A hole in the piston allows trapped air to escape as the piston is placed on the compound; then this hole is pulugged so that nothing inside the cylinder can escape.) The piston-and-cylinder apparatus is carefully placed in 10.00kg of water at 25.00 degrees C. The barometric pressure is 778 torr.