酸度系數 （英語： Acid dissociation constant，又名 酸解離常数，代號 Ka 、 pKa 、 pKa值），在 化學 及 生物化學 中，是指一個特定的 平衡常數，以代表一種 酸 解離 氫 離子 的能力。 該平衡狀況是指由一種酸（HA）中，將 氫離子 （即 質子）轉移至 水 （H 2 O）。 水的濃度 [H 2 O]是不會在系數中顯示的。 一种酸的p Ka 越大则酸性越弱，p Ka 越小则酸性越强（反過來說， Ka 值越大，解離度高，酸性越強， Ka 值越小，部份解離，酸性越弱）。 p Ka <0的酸在水中 …

2017年10月27日 · In short, the stronger the acid, the smaller the pKa value and strong acids have weak conjugate bases. pKa values describe the point where the acid is 50% dissociated (i.e. deprotonated). Below are tables that include determined pKa values for various acids as determined in water, DMSO and in the gas Phase.

pKa Scale. Definition of pKa. You can think of any molecule that has a proton on it as being an acid. They don't have to be very strong acids, but nonetheless they can behave as an acid. If you take some arbitrary acid, H-A, and place it in a solvent usually water) it will undergo an acid-base dissociation reaction as follows.

2024年10月26日 · pKa即解离常数（dissociation constant），是水溶液中具有一定解离度的溶质的极性参数。 绝大多数的药物包含可电离的基团，多数为碱性的，也有部分为酸性。 只有极少部分为中性，不能电离。 pKa是电离常数Ka的负对数。 对于酸和碱，通常均采用pKa表示。 对于酸： HA = H+ + A- pKa =-log ( [H+] [ A-]/ [HA]) 对于碱： HB+ = H+ + B. pKa =-log ( [H+] [ B]/ [HB+]) pKa表明了一种化合物的电离度，它是分子中基团与酸性、碱性的关系函数，属于酸碱质子理 …

The pKa measures how tightly a proton is held by a Bronsted acid. A pKa may be a small, negative number, such as -3 or -5. It may be a larger, positive number, such as 30 or 50.

2010年9月29日 · We’ll go through the exact details of how to use pK a values to tell if an acid base reaction is favorable or unfavorable. pK a is the negative logarithm of the acid dissociation constant, K a, which can be measured experimentally.

此数据由哈佛大学的David Ripin and David Evans收集，包括以下化合物的 pKa 。 Inorganic Acids Alcohols, Oximes, Hydroxamic Acids, and Peroxides

2014年6月22日 · Accurate and well-curated experimental pKa data of organic acids and bases in both aqueous and non-aqueous media are invaluable in many areas of chemical research, including pharmaceutical, agrochemical, specialty chemical and property prediction research.

What is pKa? pKa is a value that indicates how weak or powerful an acid is in simple terms. The pKa of a strong acid is less than zero. pKa is the negative log base ten of the Ka value, to be precise (acid dissociation constant). It determines an acid’s strength, or how tightly a proton is held by a Bronsted acid.

Acid-dissociation is a reversible reaction described by an equilibrium constant (Keq) which, for the ionization of acids is denoted as Ka. The p K a is derived from the Ka by taking its negative log. Let’s see how that works: