posted by A.A on .
Calculate the pH of concentrated hydrochloric acid if this solution is 24.8 % HCl by weight and has a density of 1.16 g/mL.
density of 1.18 g/mL. So how much does a liter weigh? It must be
1.18 g/mL x 1000 mL = 1180 grams.
How much of that is HCl (the remainder is water)? It is 24.8% HCl by weight so
1180 g x 0.248 = ?? g HCl.
Then convert ?? g HCl to mols and you will have mols/L which is the definition of molarity.
HCl ==> H^+ + Cl^-
Now take the molarity, you know HCl is 100% ionized; therefore, the molarity will be the (H^+) and you can use pH = -log(H^+) to get pH.