Blackboard and sidewalk chalk were originally made from the sedimentary rock of the same name; a form of soft limestone. Chalk, composed principally of calcium carbonate (CaCO3), formed underwater by slow accumulation and compression of the calcite shells of single-celled coccolithophores.
What is in chalk?
Chalk, soft, fine-grained, easily pulverized, white-to-grayish variety of limestone. Chalk is composed of the shells of such minute marine organisms as foraminifera, coccoliths, and rhabdoliths. The purest varieties contain up to 99 percent calcium carbonate in the form of the mineral calcite.
What are the elements present in chalk?
Composition: Chalk is a form of calcium carbonate, having the same chemical composition as ground calcium carbonate, limestone, marble, and precipitated calcium carbonate (PCC). In fact, all of the calcium carbonates listed in the previous sentence have the same crystal form, calcite.
What is the chemical formula for chalk?
Calcium carbonate (Chalk) is a chemical compound, with the chemical formula CaCO3. Calcium carbonate (Chalk) is a chemical compound, with the chemical formula CaCO3. It is a common substance found as rock in all parts of the world, and is the main component of shells of marine organisms, snails, and eggshells.