If 5.0 mL of 0.12 mmol dm-3 MB solution is diluted by adding 20.0 mL of 0.2 mol dm-3 HCl to it, what is the new MB concentration?

What is MB?

methylene blue

If this is just a dilution problem, then

0.12 mM/dm-3 x (5.0 mL/25.0 mL) = ?

Thank You

Thank You

To find the new concentration of MB solution after dilution, we need to consider the amount of MB before and after the dilution.

First, let's calculate the amount of MB before the dilution:
Amount of MB in 5.0 mL of 0.12 mmol dm-3 solution = 5.0 mL × 0.12 mmol dm-3
= 0.6 mmol

Next, let's calculate the amount of MB after the dilution:
Amount of MB after dilution = Amount of MB before dilution + Amount of MB added
= 0.6 mmol + (20.0 mL × 0.2 mol dm-3)
= 0.6 mmol + (20.0 mL × 0.2 × 10^-3 mol mL-1)
= 0.6 mmol + 4.0 × 10^-3 mol
= 0.6 mmol + 0.004 mol
= 0.604 mol

Now, let's calculate the final volume of the solution after dilution:
Final volume of solution = Volume of MB solution + Volume of HCl solution
= 5.0 mL + 20.0 mL
= 25.0 mL

Finally, let's calculate the new concentration of MB solution after dilution:
New MB concentration = Amount of MB after dilution / Final volume of solution
= 0.604 mol / 25.0 mL
= 0.02416 mol dm-3

Therefore, the new MB concentration after the dilution is approximately 0.02416 mol dm-3.