Some of the properties of acids are that they conduct electricity when they are dissolved in water, liberate hydrogen when they react with active metals and, when combined with a base, will produce a salt and a neutralized base. Acids also have a pH which is less than 7 in an aqueous solution, and will change the color of blue litmus paper to red. In an operational sense, acids increase the concentration of H+ ions when they are dissolved in water.
A lower pH of an acid in an aqueous solution indicates a greater degree of acidity, and results in a higher concentration of positive ions within the solution. Acids found in everyday life are usually found in solution. The stronger acids, such as hydrochloric acid (HCl), and some higher concentrations of weak acids tend to be corrosive.