HCl, also known as hydrochloric acid, maintains a density of 1.49 grams per cubic centimeter when measured at standard temperature and pressure values of 68 degrees Fahrenheit and 1 standard atmosphere unit. The density also depends on the molarity of the solution, related to its concentration.
As the concentration of the hydrochloric acid increases, so does its density. For example, while a 10 percent solution has a density of 1.048 grams per cubic centimeter, a hydrochloric acid solution at 38 percent concentration has the higher density of 1.189 grams per cubic centimeter. The density also varies based on the solution's temperature and pressure.