If you mixed chlorine argon and sodium together what would you expect to happen?

Sodium will react with chlorine to give you sodium chloride. Sodium will burn out. That means it is exothermic reaction. The argon is noble gas. argon will not take part in the chemical reaction or in the process of burning. Argon will act as a medium to dilute the chlorine. The end products will be same. The time to complete the burning will be little more, when chlorine is diluted with argon gas. This is just like carbon burning in the air and in pure oxygen. Carbon burns brighter in pure oxygen.