The NO 3 - ion has excess negative charge spread out over 3 oxygen atoms while the excess negative charge in NO 2 - is spread out over on 2 oxygen atoms. A conjugate base is more stable when the negative charge is on an electronegative element and when the charge is delocalized over multiple atoms. The more stable the conjugate base, the stronger the acid. A stable conjugate base is not very basic. A very strong acid has a very weak conjugate base and a very weak acid has a very strong conjugate base.
Because the concentration of water is constant, we can define a constant equal to the product of the concentration of water and the equilibrium constant. This constant, the K a is 10 We can use the K a to determine the pH of a solution of nitrous acid.
For example, let's determine the pH of a solution made from 0. This means that the concentration of NO 2 - must also be x because they form in equal amounts by the dissociation of the acid.
The concentration It is always possible to solve for x by using the quadratic equation but most of the time we can solve it using an approximation. If we assume that the extent of dissociation is small, then the equilibrium concentration of acid doesn't change very much from its original concentration. We can then use the original acid concentration in the K a expression. The approximation is a good one in this case because we get the same pH value using it as we did from the quadratic equation.
Also nitric acid is used as an strong acid and oxidizing acid in laboratories. When you are dealing with acids such as nitric acid, you should be very careful to avoid any injuries because nitric acid is an oxidizing acid. Nitrous acid contains one hydrogen atom, one nitrogen atom and two oxygen atoms. Also, there is a lone pair on nitrogen atom. HNO 2 does not dissociate completely in the water. Due to unstability of nitrous acid, it is not stored in the laboratory.
At requirement, we prepare the nitrous acid as below. This reaction is a redox reaction oxidation - reduction reaction. Solid sodium nitrite is dissolved in water to prepare aqueous sodium nitrite. No reaction is occurred in this step. Add cold dilute HCl to aqueous sodium nitrite solution.
It gives dilute nitrous acid and NaCl solution. Ostwald process is used in industry to production of nitric acid. Higher temperatures and pressure are applied in the production to get a successful yield.
When the temperature of the acid solution increases, nitric acid starts to decomposes to nitrogen dioxide , oxygen and water. Nitrogen dioxide NO 2 is a brown gas. But, nitrous acid is a weak acid and partially dissociate. This happens because conjugate base NO 3 - of nitric acid is more stable. Also, nitrous acid decomposes readily than nitric acid.
Also, oxidation numbers of nitrogen atoms are different. Nitric acid is a strong acid. But nitrous acid is a weak acid. Therefore acidic strength of nitric acid is much higher than nitrous acid.
When oxidation number increases, acidic characteristics increases. That is one reason why nitric acid is much acidic than nitrous acid.
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