What is the first step in making salt crystals through evaporation?

The first step in making salt crystals through evaporation involves ensuring safety precautions, which is why wearing goggles and tying back hair is essential. Safety measures are crucial in any laboratory procedure, especially when working with acids and other reactive substances. By wearing goggles, you protect your eyes from potential splashes or harmful vapors, while tying back hair prevents it from interfering with the experiment or catching on equipment.

Once safety is ensured, the process typically involves mixing the acid with a solid base (like copper oxide), stirring to create a solution, and then evaporating the liquid to crystallize the salt. This explains why the other choices, while part of the overall process, do not represent the initial step. Boiling the solution, stirring in the copper oxide, and letting the solution cool are important steps that follow the initial safety precautions.