**In 250 ml of solution, I have 44 ppm of copper, 11 parts per million of lead, 69 parts per million of tin. How do I convert these to grams/pounds?**

Karl-
**Pick out the target**. I'll assume that you want grams of copper, of lead, and of tin in the 250 mL of solution.**List the given information, and connect it with the target**. You know the total volume of the solution. Volume of solution can be converted into an amount of solute using concentration. Parts per million can always be expressed as g solute per 1000000 grams of solution. You don't know the density of your solution, but if it's a dilute aqueous solution you can assume that 1 mL of solution has a mass of about 1.0 g, because the density of pure water is about 1.0 g/mL. That allows you compute the g Cu in the solution as follows:250 mL soln 1.0 g soln

1 mL soln44 g Cu

1000000 g soln= 0.011 g Cu **Check the answer.**You're expecting a very small amount of copper. If there are 0.011g Cu in 250 mL solution, that corresponds to a concentration of (0.011 g Cu/250 g solution) × 10^{6}= 44 ppm Cu. Voila!

General Chemistry Online! How do I find grams of solute in a volume of solution, given parts per million?

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