A sample of 300.0g of drinking wtare is found to cntain 38 mg Pb. What is this concentration in parts per million?

1 ppm = 1 part in 1,000,000 parts.

38 mg Pb = 0.038 g.
0.038g/300 g = ?? g Pb per 1 g water.
So ??g Pb per 1,000,000 g water?

A 900.0 g sample of sea water is found to contain 6.7 x 10-3 g Zn. Express this concentration in parts per million?

Isn't this the same kind of problem?

yes can you just guide me through this one and it will be the last

Guide you through it? Do it the same way as the first one. Calculate g Zn/g water, then convert to a million grams water.

To calculate the concentration of lead (Pb) in parts per million (ppm), we need to convert the mass of Pb from milligrams (mg) to grams (g). Then, we can use the following formula:

Concentration (ppm) = (mass of solute / mass of solution) x 1,000,000

Given:
Mass of Pb = 38 mg
Mass of water = 300.0 g

Step 1: Convert the mass of Pb from mg to g:
38 mg = 38/1000 g = 0.038 g

Step 2: Calculate the concentration in ppm:
Concentration (ppm) = (0.038 g / 300.0 g) x 1,000,000
Concentration (ppm) = 126.66 ppm

Therefore, the concentration of lead (Pb) in this sample of drinking water is approximately 126.66 ppm.