Heptane and water do not mix, and heptane has a lower density (0.684 g/mL) than water (1.00 g/mL). A 100-mL graduated cylinder with an inside diameter of 3.22 cm contains 40.3 g of heptane and 31.5 g of water. What is the combined height of the two liquid layers in the cylinder? The volume of a cylinder is π r2h, where r is the radius and h is the height.