Answer :
Your question was incomplete so I am writing the down the complete question below for convenience
Q) A chemist must dilute 17.8 mL of 961. mM aqueous barium chloride BaCl 2 solution until the concentration falls to 267. mM . He'll do this by adding distilled water to the solution until it reaches a certain final volume. Calculate this final volume, in milliliters. Be sure your answer has the correct number of significant digits.
Answer:
V2 = 64.0666 mL
Explanation
Let us first write down the data
The Initial condition of Bacl2 solution is:-
M1 = 961 mM
V1 = 17.8 mL
The chemist wants to dilute the solution to reach the concentration of 267 mM hence the final conditions will be:-
M2 = 267 mM
V2 = ?
here we are going to use the simple formula to calculate V2,
M1 * V1 = M2 * V2
V2 = (M1 * V1) /M2
V2 = (961*17.8)/267
V2 = 64.0666 mL