How do you make 100 ppm of chloroform by diluting in water?

Answer 1

Well, you start by obtaining the molecular weight and density of each. They are:

Chloroform MW =119.38 g/mol; Density = 1.48 g/mL

Water MW = 18.0153 g/mol; Density = 1.00 g/mL

Then pick a volume of water to begin with. For simplicity, let's say 18.0153 mL (1 mole) of H2). Since 100 ppm means that there is 1 molecule of chloroform for every 10,000 molecules of water that means we need 1/10000th of a mole of chloroform. So just divide 119.38 grams/mole molecular weight by 10000 and we get 1.1938 x 10-3 grams. Now just divide the grams by the density 1.1938 x 10-3 g / 1.48 g*mL-1 = 8.07 x 10-4 mL or 0.807 microliters.

Practical procedure:

18.0153 mL goes into 100 mL about 5.551 times.

Since the amount of chloroform is so small we can simply add 8.07 x 10-4 mL x 5.551 = 4.48 microliters to a 100 mL volumetric flask then fill to the line with water and that should give you very very near 100 ppm chloroform water solution.