Wet chemistry is a term that represents a number of scientific techniques that involve direct experimentation with liquids. Because it is a broad industry term, the exact definition can vary from business to business. A general rule that can be applied is that if it involves a scientist working with liquids by hand and physically observing the results of the experiment, it is wet chemistry. The use of robotics in the laboratory, however, has even challenged this definition to some extent.
This type of chemistry includes basic experimentation techniques like measuring, mixing, and weighing chemicals, as well as testing concentration, conductivity, density, pH, specific gravity, temperature, viscosity, and other aspects of liquids. Analytical techniques in wet chemistry are usually qualitative in nature, meaning that they attempt to determine the presence of a specific chemical rather than the exact amount. Some quantitative techniques are used, however, and include gravimetrics (weighing) and volumetric analysis (measuring).
Bench chemistry is sometimes used as a synonym for wet chemistry. The terms differ in two primary ways: first, bench chemistry can involve dry chemicals, while wet chemistry always involves at least one substance in the liquid phase; second, wet chemistry sometimes involves high tech equipment, while bench chemistry only includes techniques that use simple devices in keeping with the classical chemistry spirit. Both types of chemistry, however, do share many of the same techniques and equipment.
NASA’s Phoenix Mars Lander had a wet chemistry lab aboard when it landed on the red planet in 2008. As one of its experiments, Phoenix scooped up small amounts of soil, then dissolved the samples in water. The soil solutions then had various aspects tested, including conductivity, pH, and redox potential. The instruments also tested for the presence of bromide anions, carbon, chloride anions, magnesium cations, oxygen, sodium cations, and sulfate anions.