Final answer:
When dilute nitric acid and zinc react, zinc dissolves to form zinc nitrate and nitrogen monoxide (NO), with different nitrogen oxides being produced depending on the concentration of the acid.
Step-by-step explanation:
When dilute nitric acid is put into zinc, a chemical reaction takes place where the zinc metal dissolves and a mixture of nitrogen oxides and zinc nitrate is formed. Unlike the reaction with hydrochloric acid, which is a simple acid-metal reaction producing hydrogen gas, nitric acid is an oxidizing acid and it tends to form nitrogen oxides (NO, NO2) instead of hydrogen gas. This is because the nitric acid undergoes reduction to nitrogen oxides while the zinc is oxidized to zinc ions.
For example, with dilute nitric acid, the reaction produces nitrogen monoxide (NO) and zinc nitrate (Zn(NO3)2), which can be crystallized upon evaporation of the solution. If you were to use concentrated nitric acid instead, you would obtain nitrogen dioxide (NO2) as a product.
Check Your Learning
For a reaction with concentrated nitric acid, the balanced equation would be:
Zn(s) + 4 HNO3(aq) -> Zn(NO3)2(aq) + 2 NO2(g) + 2 H2O(l)