To get 0.5M, I have to dissolve 186.1g of EDTA in 1L of water, isn't it? I left my 186.1g of EDTA and 800mL of water to stir overnight with a magnetic stirrer and I am hoping to see it dissolved tomorrow but I dun have much hopes. I can't afford to make another solution because the EDTA is running out. tried to make a 1M stock by dissolving 186.1g of EDTA in 500mL of water, but it REFUSES to dissolve. I went on to check that it is necessary to change the pH of the solution to 8.0 before the powder will go into the solution, but still, it DOESNT dissolve.