pKn.
/ˌpiːˈkeɪ/, U.S. /ˌpiˈkeɪ/ Chemistry.
A measure of the acidity or alkalinity of a solution of a weak electrolyte, equal to −log10K where K is the dissociation (or ionization) constant of the electrolyte.
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1929 H. T. S. Britton Hydrogen Ions iii. 43 The hydrogen-ion concentration has a pH value of ½*pKw at neutrality.
1968 R. Passmore & J. S. Robson Compan. Med. Stud. I. vi. 5/2 In a solution containing a mixture of buffers the conjugate acid base ratio is determined at any pH by its pK.
1986 P. W. Atkins Physical Chem. xii. 280 When the molalities of acid and salt are the same, pH = pKa, hence the pKa of the acid can be measured directly from the pH of the mixture.
This entry has been updated (OED Third Edition, June 2006; most recently modified version published online March 2022).
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PK
PK n. psychokinesis; (also) psychokinetic (see also quot. 1943).
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the world > the supernatural > the paranormal > [noun] > psychokinesis
mind over matter1808
telekinesis1890
psychokinesis1914
PK1943
1943 L. E. Rhine & J. B. Rhine in Jrnl. Parapsychol. 7 20 This is the first of a long series of research reports describing experiments on what is called the ‘psychokinetic’ or ‘PK’ effect. The PK effect is colloquially called ‘mind over matter’, and means the direct influencing of a physical system by the action of a subject's effort, without any known intermediate energy or instrumentation.
1973 Times 4 Dec. 17/7 There is nothing new in PK (psychokinesis) and telepathy.
1990 L. Picknett Encycl. Paranormal 207/1 Although PK has been widely reported down the centuries from many cultures, its inherent improbability and its violation of such physical laws as we think we understand has led to its general rejection by science.
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n.1929as lemmas