How many milliliters of 0.210M HCl are needed to neutralize completely 35.0ml of 0.101M Ba(OH)2 solution?

Question

How many milliliters of 0.210M HCl are needed to neutralize completely 35.0ml of 0.101M Ba(OH)2 solution?

Answer 1

2 HCl +Ba(OH)2--> BaCl2+2H2O
You see that you need two HCl for 1 BaCl2. So 1 equivalent of Ba(OH)2 corresponds to 2 equivalents of HCL

1 L of 0.101M Ba(OH)2 = 0.101 Mole of Ba(OH)
and 35ml =0.035l correspond to0.003535mole and in equivalent 0.003535*2=0.00707Eq=7.07 mEq (milliequivalent)
1L of 210M HCl = 0.21Eq =210mEq HCl
1ml=0.21mEq HCl
and you need 7.07/0.21=33.67mL

Answer 2

use the formula v1s1=v2s2
v1=x,say,that's the reqd amt of HCl
s1=0.201M
v2=35ml of Ba(OH)2
s2=0.101
calculate and you get the solution.