How do i balance chemical equations?

If a substance is not at its melting or boiling point, as the heat content of a sample of matter increases, its temperature increases the number of intermolecular bonds decreases the space between particles increases the particles move faster

Achemical reaction is done in the setup shown, resulting in a change of mass. what will happen if the same reaction is done in a sealed container that is placed on the electronic balance?

What would be the original temperature of a gas that has a volume of 2.0 l and a pressure of 2.0 atm and an unknown temperature that the volume increased to 3.5 l in its pressure decreased to 1.0 atm if the final temperature is measured to be 11°c