How much of a 15.0 M stock solution do you need to prepare 250 ml of a 2.35 M HF solution?
.25 L

250 mL

39.2 L

39.2 mL

We need 39.2 mL of the 15.0M stock solution

Explanation:

Step 1: Data given

Initial concentration ( of stock) = 15.0 M

Final volume = 250 mL = 0.250 L

Final concentration = 2.35 M

Step 2: Calculate the volume of the stock volume

C1*V1 = C2*V2

⇒with C1 = the initial concentration (stock)= 15.0 M

⇒with V1 = the volume of the stock solution = TO BE DETERMINED

⇒with C2 = the final concentration of the HF solution = 2.35 M

⇒with V2 = the final volume of the HF solution = 0.250 L

15.0 M * V1 = 2.35 M * 0.250 L

V1 = (2.35 M * 0.250 L) / 15.0 M

V1 = 0.0392 L = 39.2 mL

We need 39.2 mL of the 15.0M stock solution