Everyone gets very confused when they try to learn how to convert from g/l or mg / l, or mg / g, or something similar, to ppm. However, the process is almost identical to finding a percentage. To find a percentage (parts per hundred), you take the part, and the total and do the following:
percentage of part in total %
To find ppm (parts per million), you take the part, and the total and do the following:
parts per million ppm
Notice any similarities there?
For example, suppose after a fire we have 1 g of carbon in every litre of water in some pond. (I don’t know if this is realistic. Don’t criticise me… =P) We first convert everything to the same units. 1 litre of water is approximately 1000 g. Now, we can find the percentage of carbon in the water:
percentage % %
And the ppm of carbon in the water: