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In chemistry, hydronium (hydroxonium in traditional British English) is the cation [H 3 O] +, also written as H 3 O +, the type of oxonium ion produced by protonation of water.It is often viewed as the positive ion present when an Arrhenius acid is dissolved in water, as Arrhenius acid molecules in solution give up a proton (a positive hydrogen ion, H +) to the surrounding water molecules (H 2 O).
A strong acid is an acid that dissociates according to the reaction HA + S ⇌ SH + + A −. where S represents a solvent molecule, such as a molecule of water or dimethyl sulfoxide (DMSO), to such an extent that the concentration of the undissociated species HA is too low to be measured. For practical purposes a strong acid can be said to be ...
instead of attached to Cl − anions and the conjugate bases will be weaker than water molecules. On the other hand, if a chemical is a weak acid its conjugate base will not necessarily be strong. Consider that ethanoate, the conjugate base of ethanoic acid, has a base splitting constant (Kb) of about 5.6 × 10 −10, making it a weak base. In ...
Likewise, any aqueous base with an association constant pK b less than about 0, corresponding to pK a greater than about 14, is leveled to OH − and is considered a strong base. [ 22 ] Nitric acid , with a p K value of around −1.7, behaves as a strong acid in aqueous solutions with a pH greater than 1. [ 23 ]
Because DMSO accepts protons more strongly than H 2 O the acid becomes stronger in this solvent than in water. [11] Indeed, many molecules behave as acids in non-aqueous solutions but not in aqueous solutions. An extreme case occurs with carbon acids, where a proton is extracted from a C−H bond. [12] Some non-aqueous solvents can behave as acids.
ions, replacing the strong acids and bases with weak acids and weak bases. [13] This has the effect of damping the effect of pH changes, or reducing the pH change that would otherwise have occurred. But buffers cannot correct abnormal pH levels in a solution, be that solution in a test tube or in the extracellular fluid.
The water molecule is amphoteric in aqueous solution. It can either gain a proton to form a hydronium ion H 3 O +, or else lose a proton to form a hydroxide ion OH −. [7] Another possibility is the molecular autoionization reaction between two water molecules, in which one water molecule acts as an acid and another as a base. H 2 O + H 2 O ...
Acid–base reactions typically occur faster than any other step which may determine the product of a reaction. The conjugate base is more electron-rich than the molecule which can alter the reactivity of the molecule. For example, deprotonation of an alcohol forms the negatively charged alkoxide, which is a much stronger nucleophile.