How many mL of concentrated HCl (aq) (36.0% HCl by mass, d=1.18 g/mL are required to produce 5.00 L of a solution with a pH =2.10?

2 answers

You need two bits of information.
a. What is H^+ for pH = 2.10? pH = -log(H^+); solve for (H^+)

b. What is the molarity of the concentrated HCl?
1.18 x 1000 x 0.36 x (1 mol/36.5) = ?M

Mfrom b x mLfrom b = 5.00L x M H^+from a. Solve for mL.
1) find the concentration of H3O+ which is easy since you have the pH
2) find the number of moles of H3O+, remember c=n/v relationship
3) mole ratio! this gives you the number of moles of HCl present, it is a 1:1 ratio remember this from the chemical formula
4) Molarity of HCl this is density times 1000 and then multiply this by 0.36. Finally divide by molar mass of HCl
5) Easiest part yo! just do the c=n/v relationship again to find V since you now know molarity and number of moles