Question

In a gas laws lab experiment (producing hydrogen through reaction of magnesium with acid), will the hydrochloric in acid solution be volatile (e.g. will there be HCl vapors)? Why or why not? And what if the HCl is 4M? Explain.

Answer 1

Magnesium reacts with the HCl solution to form Magnesium chloride and Hydrogen gas.

Pure HCl is a volatile gas, but it is soluble in water and dissolves to becomes a % HCL solution.

From the HCl solution also HCl evaporates at a very low rate. The rate of evaporation increases with temperature, so yes HCl in acid is volatile but because of electrostatic interactions, Vander Waals interactions of HCl with water, the rate of evaporation is low at room temperature. HCl solution must be handled with care to avoid breathing in vapors of HCl gas.

As the molarity of HCl increases the volatility of HCl increases, 4M HCl solution contains approximately 12% (m/m)HCl in water. This is not volatile at room temperature.