Excess chlorine and hydrogen sulfide were mixed in a closed container under favorable conditions. State what was observed.

When excess chlorine and hydrogen sulfide are mixed in a closed container under favorable conditions, the following observations may be made:

1. A chemical reaction will occur between the chlorine and hydrogen sulfide, resulting in the formation of sulfur and hydrogen chloride gases.

2. The color of the mixture may change as the reaction progresses, with the initial yellow-green color of chlorine gas potentially turning to a yellow color due to the formation of sulfur.

3. A strong, pungent odor of rotten eggs may be detected, which is characteristic of hydrogen sulfide gas.

4. The pressure inside the closed container may increase as gases are produced during the reaction.

5. The temperature inside the container may increase due to the exothermic nature of the reaction between chlorine and hydrogen sulfide.

6. If the reaction is allowed to continue for an extended period of time, the container may become pressurized to the point of rupture, leading to a potential explosion.

Overall, mixing excess chlorine and hydrogen sulfide in a closed container can be dangerous and should be avoided due to the potential hazards associated with the reaction.

Observation:

The mixture reacted to form elemental sulfur (yellow powder) and hydrogen chloride (colorless gas).

Chemical Equation:

\[2Cl_2 + 2H_2S \rightarrow S_8 + 8HCl\]