What is the use of long-necked funnel in the experiment of making carbon dioxide?

The long-necked funnel has the following functions:

1. Adjust the internal and external pressures to be consistent.

Adding hydrochloric acid

3. Prevent gas leakage

It is important that the reaction can be controlled at any time. For example, when the gas is sufficient, clamp the airway and squeeze the hydrochloric acid in the bottle into the long-necked funnel with air pressure, and the reaction is over, otherwise the reaction begins.