Balenstain was studied reaction of forming HI from iodine and hydrogen vapor. He captured certain amount of iodine and hydrogen in a container which was heated until equilibrium was set up. Then container was suddenly cooled and came to "freezing" of equilibrium. After that was measured the amount of HI. The experiment was conducted at 448 Celsius and following data was provided: V0(H2)=20.53 mL V0(I2)=25.42 mL V(HI)=34.72 mL.