Question

As part of this laboratory, you may have to add iron to a solution. If you have 100 mL of a solution that contains 85 μg dL-1, how many grams of iron must be added to reach a concentration of 150 μg dL-1?

Answer 1

Answer – given, volume = 100 mL , concentration of iron = 85 µg/dL

We need to prepare 150 µg/dL

First we need to calculate the moles of iron for the 150 µg/dL concentration

We know

1 mL = 0.01 dL

100 mL = ?

= 1 dL

So, mass of iron = 150 µg/dL * 1 dL

                            = 150 µg

We know

1 µg = 1.0*10^-6 g

So, 85 µg = ?

= 8.5*10^-5 g

150 µg = 1.50*10^-4 g

We need to add the iron = 1.50*10^-4 g - 8.5*10^-5 g

                                        = 6.5*10^-5 g

6.5*10^-5 grams of iron must be added to reach a concentration of 150 μg dL-1