Aluminum sulfate octadecahydrate Al2(SO4)3.18H2O M = 666.43 g/mol CAS No. 7784-31-8 This is an international mail and delivery time can vary widely. Chemical Grade Definitions: Pure p.a - High purity analytical reagents. Suitable for laboratory and general use. Pharm/Food - Acceptable for food, drug or medicinal use. May be used for most laboratory purposes. Pure - Good quality chemicals. May be used for most laboratory purposes, educational, domestic, craft applications. Not pure enough to be offered for food. Technical - Good quality for educational, domestic, handicraft, agricultural applications. Not pure enough to be offered for food.