Question

A pharmacist needs to make a 25.0 liter of a 4.50 M solution of a substance. The stock solution of the substance is 11.5 M. How much stock and water must be mixed?

2.07 liters of stock and 25.0 liters of water
2.07 liters of stock and 22.93 liters of water
9.78 liters of stock and 25.0 liters of water
9.78 liters of stock and 15.22 liters of water

Answer 1

D) 9.78 liters of stock and 15.22 liters of water.

Step-by-step explanation:

I took the test

Answer 2

9.78 liters of stock and 15.22 liters of water.

Step-by-step explanation:

We can use the formula:

M1V1 = M2V2

where M1 is the initial concentration, V1 is the initial volume, M2 is the final concentration, and V2 is the final volume.

We know that the final volume is 25.0 liters and the final concentration is 4.50 M. We also know the initial concentration is 11.5 M.

Let's solve for the initial volume of stock solution (V1):

M1V1 = M2V2

11.5 V1 = 4.50 (25.0)

V1 = (4.50 x 25.0) / 11.5

V1 = 9.78 liters

So the pharmacist needs to mix 9.78 liters of the 11.5 M stock solution with water to make a 25.0 liter 4.50 M solution.

The remaining volume must be water, so:

Volume of water = Total volume - Volume of stock solution

Volume of water = 25.0 - 9.78

Volume of water = 15.22 liters

Therefore, the answer is:

9.78 liters of stock and 15.22 liters of water.