Posted by Andre on .
A solution is prepared by adding 50.3 mL of concentrated hydrochloric acid and 16.6 mL of concentrated nitric acid to 300 mL of water. More water is added until the final volume is 1.00 L. Calculate [H+], [OH -], and the pH for this solution. [Hint: Concentrated HCl is 38% HCl (by mass) and has a density of 1.19 g/mL; concentrated HNO3 is 70.% HNO3 and has a density of 1.42 g/mL.]
First thing calculate the molarity of HCl and HNO3.
HCl: 1.19 g/mL x 1000 mL x 0.38/molar mass HCl = approx 12M but you need to do it more accurately.
HNO3: 1.42 g/mL x 1000 mL x 0.70/molar mass HNO3 = approximately 16M.
mol H^+ from HCl = 50.3 x 12M = ?
mol H^+ from HNO3 = 16.6 mL x 16 M = ?
Total mols H^+ = sum of the two.
(H^+) = moles/L soln.
Convert to OH^- and pH.