What is the concentration in parts per million of a 500 g sample of drinking water that contains 45 mg of lead?

1 Answer

#"90 ppm"#


PPM can be better understood in typical units of concentration!

PPM can also be represented as mg/L!

Assuming the density of water is 1.0g/ml, we can translate 500.0g of water to be 500.0mL of water!


Turning 500.0mL of water into L first;

#"500 mL" * "1 L"/"1000 mL" = "0.5 L"#

For PPM, we want to keep our mass in mg, which was already supplied!

As such,

#"45 mg" /"0.5 L" = "90 mg/L" = "90 ppm"#