You can only combine positive ions with negative ions. Write the positive ions first and negative ions second. Circle the oxidation numbers and move the numbers across, diagonally, and they become the subscripts.
Na+1 Cl-1 NaCl
Mg+2 Cl-1 MgCl2
Al+3 Cl-1 -- AICI3

22. a flask containing 450 ml of 0.50 m h2so4 was accidentally knocked to the floor. how many grams of nahco, do you need to put on the spill to neutralize the acid according to the following equation: h2so4(aq)+2 nahcos(aq) na,so(aq) +2 h20()+2 co2(g) d) 38 g a) 2.3 g b) 9.5 g c) 19 g