What volume of 4N H2
SO4
is required to neutralize a solution
containing 3.7g of Ca(OH)2 per litre. Also find how many gms of pure
H2
SO4
is present in that volume?
Answers
Answer:
Avoid using an equation that looks like this: V1M1 = V2M2 or VaMa = VbMb. Such an equation works great for doing dilution problems, although the unit-factor method will just as well. But the aforementioned equation fails miserably for certain acids and bases.
Instead, use the unit-factor method just as you would for any stoichiometry problem.
HCl(aq) + NaOH(aq) → NaCl(aq) + HOH(l)
20.0 mL… 40.0mL
0.100M ……..?M
0.0200L x (0.100 mol HCl / 1L) x (1 mol NaOH / 1 mol HCl) / 0.0400L = 0.0500M NaOH
Of course, this problem is simple enough to do in your head. You don’t really need a mathematical “setup”. Since the ratio of acid to base is 1: 1 and the volume of base is twice the concentration of the acid, the base must be half has concentrated as the acid. Hence, the base is 0.05M.