What volume of .100 M NaOH will react completely with 21.00 mL of .500 M HCl?

Vb*ConcBase= Vacid*ConcAcid

Solve for Vb.

21.00 mL x .500 M HCl = 1.05e1
1.05e1 / .100 M NaOH = 1.05e2

right.

Not quite. Let me explain the correct calculation.

To find the volume of the NaOH solution (Vb) needed to react completely with a given volume of the HCl solution (Vacid) and concentration of HCl (ConcAcid), we can use the formula: Vb * ConcBase = Vacid * ConcAcid. In this case, the HCl is the acid and NaOH is the base.

Given:
Vacid = 21.00 mL
ConcAcid = 0.500 M
ConcBase = 0.100 M

Using the formula: Vb * ConcBase = Vacid * ConcAcid, we can solve for Vb:

Vb = (Vacid * ConcAcid) / ConcBase

Substituting the given values:
Vb = (21.00 mL * 0.500 M) / 0.100 M

Vb = 105.00 mL

Therefore, the volume of 0.100 M NaOH solution required to react completely with 21.00 mL of 0.500 M HCl is 105.00 mL.