Question

1. Condition for hydrogen and chlorine to combine:
(a) heat
(b) sunlight (c) catalyst
(d) pressure

​

Answer 1

Hydrogen chloride may be formed by the direct combination of chlorine (Cl2) gas and hydrogen (H2) gas; the reaction is rapid at temperatures above 250 °C (482 °F). The reaction, represented by the equation H2 + Cl2 → 2HCl, is accompanied by evolution of heat and appears to be accelerated by moisture.