Weak Acids

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Why space acids weak or strong?

Every acid reacts through water. When it loser a proton, it transfers that proton to water. Water acts together a base as soon as it solvates the proton. The conjugate acid is protonated water and it is represented as (H3O)+, (H5O2)+, (H2nOn)+, or just as H+(aq). The conjugate base is the mountain minus the proton.A strong acid is fully dissociated in water when a weak acid is in equilibrium with its conjugate base in water. Let"s look at the reaction the a strong acid, nitric mountain or HNO3, and a weaker acid, nitrous mountain or HNO2, in water.

You are watching: The conjugate acid of no2- is ________.

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Nitric acid is a more powerful acid than nitrous acid because its conjugate basic is more stable. The NO3- ion has excess negative charge spread out out end 3 oxygen atom while the excess an adverse charge in NO2- is spread out out over on 2 oxygen atoms.A conjugate base is an ext stable when the an adverse charge is on one electronegative element and also when the charge is delocalized end multiple atoms. The more stable the conjugate base, the stronger the acid. A steady conjugate base is not really basic. A very solid acid has a really weak conjugate base and a an extremely weak acid has actually a very strong conjugate base.

Weak acid Equilibrium

Nitrous acid is in equilibrium with a proton and also its conjugate base, NO2-. Because the concentration that water is constant, us can define a consistent equal come the product of the concentration of water and also the equilibrium constant. This constant, the Ka is 10-3.29 for HNO2.
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We deserve to use the Ka to identify the pH that a solution of nitrous acid. For example, let"s identify the pH the a equipment made indigenous 0.01 mole that HNO2 in 1.0 together of water. Few of the acid will dissociate into H+ and also NO2- but we don"t recognize w=how much. We"ll contact the molar concentration that solvated proton x for this reason = x. This method that the concentration the NO2- must likewise be x because they type in equal amounts by the dissociation of the acid. The concentration
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It is always possible to fix for x by making use of the quadratic equation yet most of the time we can solve it making use of an approximation. If we assume that the level of dissociation is small, then the equilibrium concentration of acid doesn"t change really much from its original concentration. We can then use the original acid concentration in the Ka expression.The approximation is a good one in this case due to the fact that we obtain the very same pH value using it together we walk from the quadratic equation.

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Reaction in between Weak mountain and solid Bases

Strong bases react totally with weak bases to kind the conjugate base of the weak acid. Climate there will be an equilibrium in between the weak acid and also its conjugate base in water. For example, let"s look in ~ the solution created by mixing 0.010 mol HNO2 and 0.004 mol NaOH in 1.0 together water. Again, we have the right to use an approximation to deal with this. The approximation is valid because the degree of dissociation will be tiny when over there is already some product present.
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Weak mountain and solid Acids

The mountain dissociation constants the a choice of acids is in the tables. In the table are listed pKa values. pKa = -log(Ka)The very solid acids, those the are totally dissociated in water, are differentiated by examining their mountain dissociation equilibrium in non-aqueous solvents and also the pKa because that water is estimated. The equilibrium constants because that the weaker acids (pKa >0) are determined from pH measurements of solutions.BackCompassIndexTablesIntroductionNextProfessor Patricia Shapley, college of Illinois, 2011