Sunday, December 11, 2011

Chemistry: Finding Conjugate Base?

On the left side of the equation, HNO3 is the acid. It gives up a proton to the base NaOH. So H+ is the acid and OH- is the base on the left side. Now think of the reaction proceeding in the opposite direction (although it would not since HNO3 and NaOH are strong) and look at the right side of the equation. What would give up a proton? It has to be water since it is the only compound that has protons on the right side of the equation. What accepts those protons? Answer: the nitrate ion. So on the right hand side, the nitrate ion is the conjugate base. However, this is kind of a trick question, because the nitrate ion does not act as a base; it will never accept a proton to become nitric acid in water solution. Why? Because nitric acid is a strong acid. That means it is always 100% dissociated in water. So, NO3- can't pick up a proton to become HNO3 in water. This means that if you take a nitrate salt like NaNO3 and dissolve it in water, the pH will not change. The nitrate ion will not react with the water to produce HNO3.

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