Dilute laboratory bench reagents are generally 6.0 M.What volume of dilute HCl must be used to prepare 5.00 * 10² mL of 0.25 M HCl?

Question

Quizplus · Accepted Answer

Using the formula:

M1 V1 = M2 V2

Where: 
M1 = concentrated solution concentration (6.0 M) 
V1 = volume of concentrated solution we need to add (unknown) 
M2 = final concentration (0.25 M) 
V2 = final volume (5.00 x 10^-3 L)

Solving for V1:

(6.0 M) V1 = (0.25 M) (5.00 x 10^-3 L)

V1 = (0.25 M) (5.00 x 10^-3 L) / (6.0 M)

V1 = 20.8 x 10^-3 L

V1 = 20.8 mL

Therefore, we need to add 20.8 mL of concentrated HCl to prepare 5.00 mL of 0.25 M HCl. However, we need to use significant figures in our final answer, so we will round up to 21 mL. Thus, the correct choice is B.

Dilute Laboratory Bench Reagents Are Generally 6