Complete the exercises below. In aqueous solution, hydrogen sulfide reduces dilute HNO₃ to NO₂. In all cases, under appropriate conditions, the product is elemental sulfur. Write a balanced net ionic equation for each reaction.

Redox (reduction-oxidation) reactions involve the transfer of electrons between species, resulting in changes in oxidation states. In this context, hydrogen sulfide (H₂S) acts as a reducing agent, donating electrons to nitric acid (HNO₃), which is reduced to nitrogen dioxide (NO₂). Understanding the oxidation states of the elements involved is crucial for balancing the reaction.

A net ionic equation represents the actual chemical species participating in a reaction, excluding spectator ions that do not change during the reaction. To write a net ionic equation, one must first identify the reactants and products, then eliminate the ions that remain unchanged. This simplification helps focus on the essential chemical changes occurring in the solution.

Balancing chemical equations ensures that the number of atoms for each element is the same on both sides of the equation, adhering to the law of conservation of mass. This process involves adjusting coefficients in front of compounds to achieve balance. In the case of the reaction between H₂S and HNO₃, careful attention must be paid to the stoichiometry to accurately reflect the formation of elemental sulfur and nitrogen dioxide.