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How to Convert Picomoles to Milligrams

Chemists working in the metric system have a variety of units at their disposal to describe chemical quantities. One common unit is the mole, which stands for 6.02 x 10^23 atoms or molecules of a substance. The metric system uses a series of standard prefixes to indicate magnitude and the prefix "pico" means there are 1 x 10^12 picomoles (pmol) in a mole. Grams (g) are a standard metric unit of mass and a milligram (mg) is one thousandth of a gram.

Things You'll Need

Calculator
Chemical molecular weight

Instructions

- 1
  Multiply the quantity of your chemical, in units of picomoles, by 1 x 10^-12. This calculation converts the units of chemical quantity into moles since there are 1 x 10^12 picomoles in a mole. For example, if you were working with a quantity of 500 pmol of sodium chloride (NaCl), you would multiply 500 by 1 x 10^-12 to obtain 5 x 10^-10 mol NaCl.
- 2
  Multiply the value you just obtained by the molecular weight of your chemical. This is the mass of the chemical, in grams, per mole. This calculation gives you the grams of your chemical. You can obtain the molecular weight of a chemical from the manufacturer's information for that substance, such as the Material Safety Data Sheet (MSDS). In the case of the example, the molecular weight of NaCl is 58.44 g/mole so you would calculate 58.44 g/mole times 5 x 10^-10 resulting in 2.922 x 10^-8 g NaCl.
- 3
  Multiply the value from your most recent calculation by 1000. Since there are 1000 milligrams in a gram, this converts the units of chemical mass into milligrams. You have now completed the conversion. In the case of the example, you would multiply 2.922 x 10^-8 g by 1000 to obtain a mass of 2.922 x 10^-5 mg NaCl.

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