What is the concentration in parts per million of a 500 g sample of drinking water that contains 45 mg of lead?
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;
For PPM, we want to keep our mass in mg, which was already supplied!