Pure water at 25°C

ionizes in the presence of acid to form an equilibrium in which

StartBracket upper H subscript 3 upper O superscript plus EndBracket equals StartBracket upper O upper H superscript minus EndBracket equals 10 to the 7 moles per liter.

ionizes in the presence of acid to form an equilibrium in which

StartBracket upper H subscript 3 upper O superscript plus EndBracket equals StartBracket upper O upper H superscript minus EndBracket equals 10 to the negative 7 moles per liter.

self-ionizes to form an equilibrium in which StartBracket upper H subscript 3 upper O superscript plus EndBracket equals StartBracket upper O upper H superscript minus EndBracket equals 10 to the 7 moles per liter.

self-ionizes to form an equilibrium system in which

StartBracket upper H subscript 3 upper O superscript plus EndBracket equals StartBracket upper O upper H superscript minus EndBracket equals 10 to the negative 7 moles per liter.

The last statement describes the correct inozation of water:

Pure water at 25ºC:

Explanation:

It has been proven that pure water slightly conducts electricity. This fact, explained by the Arrhenius model of acids, would mean that pure water contains ions.

Since such ions are spontaneoulsy produced by the water molecules, this phenomenum is called self-ionization of water.

The equilibrium equation that represents the self-ionization of water is:

The expression for the equilibrium constant is:

As per the stoichiometry:

The equilibrium constant for the self-ionization of water has been determined at several temperatures. At 25ºC it is equal to 1.0×10⁻¹⁴.

Then by solving the equation you can find the concentrations of the ions:

Hence, we have proved that pure water self-ionizes to form an equilibrium system in which:

most historians agree that gabriel mouton, the vicar of st. paul’s church in lyons, france, is the “founding father” of the metric system. he proposed a decimal system of measurement in 1670. mouton based it on the length of one minute of arc of a great circle of the earth (now called a nautical mile, 1852 meters). he also proposed the swing-length of a pendulum with a frequency of one beat per second as the unit of length (about 25 cm). a pendulum beating with this length would have been fairly easy to produce, thus facilitating the widespread distribution of uniform standards. over the years, his work was revised, improved, and extended by a number of french scientists.

the political sponsor of weights and measures reform in the french revolutionary national assembly was the bishop of autun, better known as talleyrand. under his auspices, the french academy appointed several committees to carry out the work of developing a usable system of weights and measures for france. one of the committees recommended a decimalized measurement system based upon a length equal to one ten-millionth of the length of a quadrant of the earth’s meridian (i.e., one ten-millionth of the distance between the equator and the north pole).