When a small amount of hydrochloric acid (hcl) is added to a solution of na2hpo4, the ph of the solution does not change markedly. the ph also does not change drastically when a small amount of sodium hydroxide (naoh) is added to this same solution. based on these observations, the compound na2hpo4 is: ?

Answer;

Based on these observations, the compound na2hpo4 is acting as a buffer.

Explanation;

-A Buffer is a solution that can resist changes pH. A buffer is a solution that can maintain a nearly constant pH if it is diluted, or if relatively small amounts of strong acids or bases are added. A buffer is prepared by combining a weak acid and its salt with a strong base (conjugated base) or, analogously, a weak base and its salt with a strong acid (conjugated acid).  

- NaH2PO4 and Na2HPO4 are an acid/base conjugate pair. They make an excellent buffer. This is called a phosphate buffer, where Na2HPO4 is the salt, conjugate base, while NaH2PO4 is the weak acid.

your answer would be a. 12.5 kg