Sodium chloride and calcium chloride have very similar sounding names. But their similarities end there. Sodium chloride and calcium chloride possess significantly different physical, chemical and biological properties. These differences result in different practical real-world applications. Similarly, within your body, sodium and calcium ions play contrasting roles, particularly with regard to their effects on blood pressure and bone formation.
Chemistry
Sodium chloride and calcium chloride differ chemically. Sodium chloride consists of two atoms; one sodium atom bonded to one chloride atom. Each sodium atom has a single positive charge that balances the single negative charge from each chloride atom. Calcium atoms contain two positive charges per atom. Therefore, calcium chloride consists of three atoms; one calcium atom bonded to two chloride atoms. Because of the different net charges on the individual atoms, their crystal structures are different. Sodium chloride forms into a crystalline cubic lattice, a square box shape with square ends, while calcium chloride forms orthorhombic shaped crystals, a rectangular box with rectangular ends.
Physical Properties
Because of their different chemical properties, calcium chloride and sodium chloride also possess different physical properties. Sodium chloride consists of clear to white crystals, while crystals of calcium chloride appear more white to grayish-white. Calcium chloride melts at about 1,422 degrees Fahrenheit while it takes just slightly higher temperatures to melt sodium chloride crystals, about 1,473 degrees. Similarly, the point at which calcium chloride boils is about 2,912 degrees, while sodium chloride boils at a temperature 243 degrees lower, about 2,669 degrees. Solutions of sodium chloride are slightly acidic, having a pH around 6.7 to 7.3 compared to the more basic pH of 8 to 9 for calcium chloride solutions.
Deicer
The physical and chemical differences between calcium chloride and sodium chloride have practical applications. Widely used as a deicer, calcium chloride effectively lowers the melting point of ice upon contact. The amount of melting salt can achieve is directly proportional to the number of particles in that salt. The effectiveness of calcium chloride compared to sodium chloride results from the fact that each molecule of calcium chloride produces three particles or ions, in solution compared to two for sodium chloride. In addition, calcium chloride melts ice down to temperatures as low as negative 25 degrees, whereas sodium chloride loses its effectiveness at about 20 degrees.
Blood Pressure
High blood pressure, also known as hypertension, affects about 50 million Americans. Sodium chloride, or table salt, increases average levels of blood pressure, although some individuals are more affected than others. By contrast, solutions of calcium chloride may cause a moderate fall in blood pressure. Because of the role sodium chloride plays in hypertension, the 2010 Dietary Guidelines for Americans as well as the Institute of Medicine recommend limiting sodium chloride intake to about 1,500 mg to 2,300 mg per day. Most Americans consume sodium in quantities far exceeding these amounts and often look for ways to decrease their intake. Opposite concerns exist in terms of the consumption of calcium. About 55 percent of adult men and 78 percent of adult women and 87 percent of girls ages 12 through 19 do not meet their recommended intake for calcium.
Osteoporosis
Calcium chloride and sodium chloride play opposing roles in osteoporosis. Osteoporosis, a multi-factorial skeletal disorder resulting in decreased bone density, increases your risk of bone fracture. Bone density depends on many factors, including an adequate intake of calcium. Calcium helps build strong bones. Sodium, however negatively impacts that relationship. Increased sodium intake increases urinary excretion of calcium, making that calcium unavailable for incorporation into bone. Eventually, this leads to an overall decrease in bone density. Increasing calcium consumption while decreasing sodium consumption can help prevent and treat osteoporosis by reducing the amount of bone resorption and calcium excretion.
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