CONCENTRATED SULPHURIC ACID INTO WATER OR WATER INTO CONCENTRATED SULPHURIC ACID!!!
How do you dilute the concentrated sulphuric acid? When you mix water and concentrated sulphuric acid (H2SO4) it may present safety lab hazards . Reaction between sulphuric acid and water is highly exothermic. Remember ! Always pour acid into large volume of water - water will absorb all heat of hydration- slowly and gradually to dilute the sulphuric acid otherwise, mixing of water into sulphuric acid is highly exothermic reaction.The reaction mixture can boil and spit out of container, can be cause of nasty acid burns.