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Pauling's second rule is that the value of the first pK a for acids of the formula XO m (OH) n depends primarily on the number of oxo groups m, and is approximately independent of the number of hydroxy groups n, and also of the central atom X. Approximate values of pK a are 8 for m = 0, 2 for m = 1, −3 for m = 2 and < −10 for m = 3. [28]
For instance, hydrogen fluoride, whether dissolved in water (= 3.2) or DMSO (= 15), has values indicating that it undergoes incomplete dissociation in these solvents, making it a weak acid. However, as the rigorously dried, neat acidic medium, hydrogen fluoride has an H 0 {\displaystyle H_{0}} value of –15, [ 1 ] making it a more strongly ...
The higher the proton affinity, the stronger the base and the weaker the conjugate acid in the gas phase.The (reportedly) strongest known base is the ortho-diethynylbenzene dianion (E pa = 1843 kJ/mol), [3] followed by the methanide anion (E pa = 1743 kJ/mol) and the hydride ion (E pa = 1675 kJ/mol), [4] making methane the weakest proton acid [5] in the gas phase, followed by dihydrogen.
Boric acid, more specifically orthoboric acid, is a compound of boron, oxygen, and hydrogen with formula B(OH) 3. It may also be called hydrogen orthoborate , trihydroxidoboron or boracic acid . [ 3 ]
In the clear atmosphere, with only nitrogen and oxygen, ozone can react with the atomic oxygen to form two molecules of O 2: O 3 + O 2 O 2 {\displaystyle {\ce {O3 + O -> 2 O2}}} An estimate of the rate of this termination step to the cycling of atomic oxygen back to ozone can be found simply by taking the ratios of the concentration of O 2 to O 3 .
A-values can help predict the steric effect of a substituent. In general, the larger a substituent's A-value, the larger the steric effect of that substituent. A methyl group has an A-value of 1.74 while tert-butyl group has an A-value of ~5. Because the A-value of tert-butyl is higher, tert-butyl has a larger steric effect than methyl. This ...
(3-Aminopropyl)triethoxysilane (APTES) is an aminosilane frequently used in the process of silanization, the functionalization of surfaces with alkoxysilane molecules. It can also be used for covalent attaching of organic films to metal oxides such as silica and titania.
See Amino acid for the pK a values of all amino acid side chains inferred in such a way. There are also numerous experimental studies that have yielded such values, for example by use of NMR spectroscopy. The table below lists the model pK a values that are often used in a protein pK a calculation, and contains a third column based on protein ...