hydrogen ions, which are the basic units of positive charge (protons), can have drastic effects on other molecules in solution A structure that is stable with a few protons around may be unstable when many protons are in the vicinity So significant is the proton concentration that humans have a specialized taste sensation to estimate it: sourness Our term for the class of chemicalcompounds that release protons into solutions, acids, derives from the Latin acere, meaning to taste sour We call the complementary chemical group that accepts protons and neutralizes them, bases or alkalis The properties of acids and bases affect us continually in our daily life Practically every food we eat, from steak to coffee to oranges, is at least slightly acidic And the degree of acidity of the cooking medium can have great influence on such characteristics as the color of fruits and vegetables and the texture of meat and egg proteins Some measure of acidity would clearly be quite useful A simple scale has been devised to provide just that The pH Scale The standard measure of proton activity in solutions is pH, a term suggested by the Danish chemist S P L Sørenson in 1909 It’s essentially a more convenient version of the minuscule percentages of molecules involved (for some details, see box below) The pH scale runs from to 14 The pH of neutral, pure water, with equal numbers of protons and OH ions, is set at A pH lower than 7 indicates a greater concentration of protons and so an acidic solution, while a pH above indicates a greater prevalence of proton-accepting groups, and so a basic solution Here’s a list of common solutions and their usual pH Liquid pH Human gastric juice 1.3–3.0 ... lower than 7 indicates a greater concentration of protons and so an acidic solution, while a pH above indicates a greater prevalence of proton-accepting groups, and so a basic solution Here’s a list of common solutions and their usual pH... that The pH Scale The standard measure of proton activity in solutions is pH, a term suggested by the Danish chemist S P L Sørenson in 1909 It’s essentially a more convenient version of the minuscule... minuscule percentages of molecules involved (for some details, see box below) The pH scale runs from to 14 The pH of neutral, pure water, with equal numbers of protons and OH ions, is set at A pH