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For acid–base reactions, the equivalent weight of an acid or base is the mass which supplies or reacts with one mole of hydrogen cations (H +). For redox reactions, the equivalent weight of each reactant supplies or reacts with one mole of electrons (e −) in a redox reaction. [3]
An equivalent (symbol: officially equiv; [1] unofficially but often Eq [2]) is the amount of a substance that reacts with (or is equivalent to) an arbitrary amount (typically one mole) of another substance in a given chemical reaction. It is an archaic quantity that was used in chemistry and the biological sciences (see Equivalent weight § In ...
A weak acid cannot always be neutralized by a weak base, and vice versa. However, for the neutralization of benzoic acid (K a,A = 6.5 × 10 −5) with ammonia (K a,B = 5.6 × 10 −10 for ammonium), K = 1.2 × 10 5 >> 1, and more than 99% of the benzoic acid is converted to benzoate.
Normality can be used for acid-base titrations. For example, sulfuric acid (H 2 SO 4) is a diprotic acid. Since only 0.5 mol of H 2 SO 4 are needed to neutralize 1 mol of OH −, the equivalence factor is: f eq (H 2 SO 4) = 0.5. If the concentration of a sulfuric acid solution is c(H 2 SO 4) = 1 mol/L, then its normality is 2 N. It can also be ...
Historically, the mole was defined as the amount of substance in 12 grams of the carbon-12 isotope.As a consequence, the mass of one mole of a chemical compound, in grams, is numerically equal (for all practical purposes) to the mass of one molecule or formula unit of the compound, in daltons, and the molar mass of an isotope in grams per mole is approximately equal to the mass number ...
An acid mixture consists of 0.76, 0.04, and 0.20 mass fractions of 70% HNO 3, 49% HF, and H 2 O, where the percentages refer to mass fractions of the bottled acids carrying a balance of H 2 O. The first step is determining the mass fractions of the constituents:
That is, the molar mass of a chemical compound expressed in g/mol or kg/kmol is numerically equal to its average molecular mass expressed in Da. For example, the average mass of one molecule of water is about 18.0153 Da, and the mass of one mole of water is about 18.0153 g.
[9] [10] [11] The related concept of equivalent mass had been in use at least a century earlier. [12] In chemistry, it has been known since Proust's law of definite proportions (1794) that knowledge of the mass of each of the components in a chemical system is not sufficient to define the system. Amount of substance can be described as mass ...