You have 220mL of a 10% solution (w/v). You need to prepare a 1:200 solution. Howmuch diluent will you add to the stock solution?

To solve this problem, you first need to understand what a 1:200 dilution means. This means that 1 part of the solution is diluted in 199 parts of the diluent.

1. First, calculate the amount of solute in the original solution. Since it's a 10% w/v solution, this means there are 10g of solute in every 100mL of solution. So, in 220mL of solution, there are (10g/100mL)*220mL = 22g of solute.

2. Now, you need to figure out how much of the 1:200 solution this 22g of solute can make. Since 1 part of the 1:200 solution is the solute, this means the 22g of solute can make 22g * 200 = 4400g of the 1:200 solution.

3. Convert this mass to volume. Assuming the density of the solution is approximately 1g/mL (which is a reasonable assumption for many liquids), this means you need to prepare 4400mL of the 1:200 solution.

4. Subtract the volume of the original solution from this. 4400mL - 220mL = 4180mL.

So, you need to add 4180mL of diluent to the 220mL of the 10% solution to prepare a 1:200 solution.