Search results
Results From The WOW.Com Content Network
A smaller H + concentration means a greater OH − concentration and, therefore, a greater K b and a greater pH. NaOH (s) (sodium hydroxide) is a stronger base than (CH 3 CH 2) 2 NH (l) (diethylamine) which is a stronger base than NH 3 (g) (ammonia). As the bases get weaker, the smaller the K b values become. [1]
The concentration of hydroxide ions can be expressed in terms of pOH, which is close to (14 − pH), [note 3] so the pOH of pure water is also close to 7. Addition of a base to water will reduce the hydrogen cation concentration and therefore increase the hydroxide ion concentration (decrease pH, increase pOH) even if the base does not itself ...
pOH is sometimes used as a measure of the concentration of hydroxide ions, OH −. By definition, pOH is the negative logarithm (to the base 10) of the hydroxide ion concentration (mol/L). pOH values can be derived from pH measurements and vice-versa. The concentration of hydroxide ions in water is related to the concentration of hydrogen ions by
Water molecules dissociate into equal amounts of H 3 O + and OH −, so their concentrations are almost exactly 1.00 × 10 −7 mol dm −3 at 25 °C and 0.1 MPa. A solution in which the H 3 O + and OH − concentrations equal each other is considered a neutral solution. In general, the pH of the neutral point is numerically equal to 1 / 2 ...
The relative activity of a species i, denoted a i, is defined [4] [5] as: = where μ i is the (molar) chemical potential of the species i under the conditions of interest, μ o i is the (molar) chemical potential of that species under some defined set of standard conditions, R is the gas constant, T is the thermodynamic temperature and e is the exponential constant.
The molar concentration of hydronium or H + ions determines a solution's pH according to pH = -log([H 3 O +]/M) where M = mol/L. The concentration of hydroxide ions analogously determines a solution's pOH. The molecules in pure water auto-dissociate into aqueous protons and hydroxide ions in the following equilibrium: H 2 O ⇌ OH − (aq) + H ...
In order to study gas phase interstellar chemistry, it is convenient to distinguish two types of interstellar clouds: diffuse clouds, with T=30-100 K, and n=10–1000 cm −3, and dense clouds with T=10-30K and density n= 10 4-10 3 cm −3. Ion chemical routes in both dense and diffuse clouds have been established for some works (Hartquist 1990).
The atmospheric pressure is roughly equal to the sum of partial pressures of constituent gases – oxygen, nitrogen, argon, water vapor, carbon dioxide, etc.. In a mixture of gases, each constituent gas has a partial pressure which is the notional pressure of that constituent gas as if it alone occupied the entire volume of the original mixture at the same temperature. [1]