The best tool to find the volume of the base taht she needs to neutralize the acid is M1V1 = M2V2. an example is given below.
Given:
12.0 M HCl
2.0 liters of a 3.0 M HCl
Required:
volume of concentrated hydrochloric acid
Solution:
M1V1 = M2V2
(12.0 M HCl)V1 = (3.0 M HCl)( 2.0 liters)
V1 = (3.0 M HCl)( 2.0 liters)/ (12.0 M HCl)
V1 = 0.5 liters