text: find ph, help? a solution is prepared by adding 48.8 ml of concentrated hydrochloric acid and 17.5 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.]  how do i find ph you need to find the moles of h+  38% by mass hcl means that you have 38 g of hcl for every 100 g of solution.  density=mass/volume => v=m/d  using this equation you convert the mass of solution to volume and thus you can convert the concentration to g of hcl per 1l of solution.  also mole=mass/mw where mw is the molecular weight. using this convert the g hcl/l to mole/l.  hcl is monoprotic (1 molecule gives 1 h+) and it is a strong acid (complete dissociation). so the mole of h+ coming from hcl will be equal to the mole of hcl = m1*v1. m1 you calculated before, v=0.0488 l. substitute and you find how many moles h+ come from hcl.  in the same way you find the moles of h+ coming from hno3 =m2*v2 (find m2 as you found m1 and v2=0.0175 l)  your final volume is 1l so the concentration of h+ is  [h+]= moles h+/vfinal= (m1v1+m2v2)/vfinal  ph=-log[h+]  and [oh-]=kw/[h+]= 10^-14 /[h+] or if you prefer  poh=14-ph and [oh-]=10^-poh