What impact would adding twice as much na2co3 than required for stoichiometric quantities have on the quantity of product produced?

If too much of Na2Co3 is added to a particular chemical reaction, there will be a shortage of the other reactant which is supposed to react with the Na2Co3 and this will leads to excess production of the product. Stoichiometric should always be used to obtain information about the appropriate quantities of chemicals that should be used during chemical reactions.