A ruptured tank in Anywhere, USA, spilled

hydrochloric acid. Officials were reported to
be concerned that the acid might mix with
sodium hydroxide (caustic soda) in a neigh-
boring tank and form a toxic gas. What toxic
gas would be formed by mixing hydrochloric
acid with sodium hydroxide?
1. carbon dioxide
2. chlorine dioxide
3. None
4. chlorine

HCl + NaOH --> H2O + NaCl so 3. None

The toxic gas that would be formed by mixing hydrochloric acid with sodium hydroxide is chlorine gas. To get this answer, we need to understand the reaction between hydrochloric acid (HCl) and sodium hydroxide (NaOH), which is a classic example of an acid-base neutralization reaction.

In this reaction, the hydrogen ion (H+) from the hydrochloric acid combines with the hydroxide ion (OH-) from the sodium hydroxide to form water (H2O). The remaining ions, sodium (Na+) and chloride (Cl-), do not react further.

The balanced chemical equation for this reaction is:

HCl + NaOH -> NaCl + H2O

So, when hydrochloric acid is mixed with sodium hydroxide, they neutralize each other, resulting in the formation of sodium chloride (NaCl) and water (H2O). No toxic gas is produced in this reaction.

Therefore, the correct answer is option 3: None.

2B