First thing, we need to know the chemical equation for each neutralization reaction. Then, determine the amount in moles needed hydrochloric acid. We do as follows:
HCl + NaOH = NaCl + H2O
0.300 M NaOH ( .014 L ) ( 1 mol HCl / 1 mol NaOH ) ( 1 L / 0.500 M HCl ) = 0.0084 L HCl solution or 8.4 mL of 0.500 M HCl
2HCl + Ba(OH)2 = BaCl2 + 2H2O
0.200 M Ba(OH)2 (0.019 L ) ( 2 mol HCl / 1 mol Ba(OH)2 ) ( 1 L / 0.500 M HCl ) = 0.0152 L HCl solution or 15.2 mL of 0.500 M HCl
