# Question #dfb12

##### 1 Answer

The concentration of PNP is 180 µmol/L.

We have to assume that the volume does not change when you add the PNP to the NaOH solution. If the volume changed by ±1.25 µL, the change would be ±1 %. You should check with your instructor if this assumption is allowed.

**Step 1.** Calculate the concentration of PNP before dilution.

**Step 2.** Calculate the concentration of PNP after dilution.

You added 12.0 µL to 488 µL, so your new volume was 500 µL. Now we do a simple dilution calculation.