function execute_reaction(rxn,rxn_num)

global molecdata

for i = 1:length(rxn{rxn_num}.subs(:,1))
    molnum = rxn{rxn_num}.subs(i,2);
    molecdata(molnum) = molecdata(molnum) - rxn{rxn_num}.subs(i,1);
end

for i = 1:length(rxn{rxn_num}.prods(:,1))
    molnum = rxn{rxn_num}.prods(i,2);
    molecdata(molnum) = molecdata(molnum) + rxn{rxn_num}.prods(i,1);
end