500 gm zinc sulphate and 280 gm iron sulphate ( total weight 780gm ) were taken in flask and water is added to make final volume 1 liter. the solution is heated to dissolve the zinc and iron sulphate in water completely. after heating any water loss is compensated by adding water and making final volume to 1 liter. the problem is after cooling down the solution zinc and iron sulphate is getting recrystallize to some extent and crystals are settling down at bottom and side of flask. is there any chemical that can be added to prevent the recrystallization of salt. i want to keep the iron and zinc sulphate fully dissolved in water even after solution cools down.
any suggestions or help is appreciated.