Which type of fluoride should not be mixed with chlorine?

Hydrofluoric acid (HFS acid) is a highly corrosive and dangerous chemical known for its ability to react violently with chlorine. The main concern when mixing HFS acid with chlorine is the potential for the production of toxic gases, which can occur due to a chemical reaction between the two substances. This reaction is hazardous and can lead to serious health risks, including respiratory issues and chemical burns.

In contrast, other types of fluoride, such as sodium fluoride, calcium fluoride, and potassium fluoride, do not present the same level of danger in combination with chlorine, making them less of a concern in operational contexts. Therefore, HFS acid is the one type of fluoride that should be strictly avoided for mixing with chlorine due to its dangerous reactive properties.