When the school worker was cleaning the bathroom, Xiao Hao smelled a very choking smell and saw it

Because concentrated hydrochloric acid is volatile, hydrogen chloride gas is easy to volatilize into the air and combine with water vapor in the air to form small droplets of hydrochloric acid, thus forming a white mist, 3) the identification of hydrochloric acid should be completed in two steps is to use litmus test solution and other identification solutions are acidic is to use AgNO3

solution and dilute nitric acid to check whether the solution contains chloride ions;

Reflection and communication: In the experiment done by Xiao Hao, if experiment 1 is omitted, it will not affect the conclusion, mainly because the knowledge of experiment 1 proves that hydrochloric acid cleaning toilets are similar to cleaners on the surface, and it cannot prove that the detergent contains hydrochloric acid;

Since hydrogen chloride gas is harmful to the human body and is easily soluble in water, it is recommended that workers open the ventilation fan in the bathroom to ventilate the hydrogen chloride gas as soon as possible, and cover their mouths and noses with wet towels;

Therefore, the answer is: concentrated hydrochloric acid is volatile;

Operation. Phenomenon.

Conclusions. Put a little detergent into a tube and add purple litmus drops.

The litmus solution turns from purple to red.

The liquid is acidic.

Take a little detergent and drop a little into another tube, and add AgNO3 solution and dilute nitric acid dropwise.

Produces a white precipitate.

Insoluble in dilute nitric acid).

This solution contains chloride ions.

Reflective Communication: Experiment 1; Turn on the ventilation fan in the bathroom to ventilate and cover your mouth and nose with a wet towel;