If 20 mL of a 2% (w/v) solution are diluted with water to 8 pints, what is the ratio strength (w/v) of thedilution?

To solve this problem, we need to first understand the given information and then apply the appropriate calculations.

1. We have a 2% (w/v) solution. This means that there are 2 grams of solute in every 100 mL of solution.

2. We are taking 20 mL of this solution. So, the amount of solute in this 20 mL is (2/100)*20 = 0.4 grams.

3. This 20 mL solution is diluted to 8 pints. We need to convert this volume to mL because our initial concentration was given in mL. 1 pint is approximately 473.176 mL. So, 8 pints are approximately 3785.41 mL.

4. Now, we need to find the new concentration (w/v) after dilution. The weight of the solute remains the same (0.4 grams), but the volume has increased. So, the new concentration is (0.4/3785.41)*100 = 0.0106% (w/v).

So, the ratio strength (w/v) of the dilution is 0.0106%.