Help please!

[tradanger]

I've been doing some questions and I'm unsure of how to do this one, can anyone help me here?

A sample of water contains 0.010 ppm lead nitrate.
a. Calculate the mass of lead ions per litre in this solution. (Assume the density of the water solution is 1.0g/ml)
b. What is the lead concentration in ppb?

Any clues to start with?

Thanks in advance!

[Phy124]

I've been doing some questions and I'm unsure of how to do this one, can anyone help me here?

A sample of water contains 0.010 ppm lead nitrate.
a. Calculate the mass of lead ions per litre in this solution. (Assume the density of the water solution is 1.0g/ml)
b. What is the lead concentration in ppb?

Any clues to start with?

Thanks in advance!

0.010 ppm means you have 0.010 x per 10⁶ y

0.010 μL per 0.010 x 10⁶μL = 0.010 μL per L

Remember that 1 gram = 1 mL (As density = 1.0g/ml)

so 1 mg = 1 μL

Therefore 0.010 mg PbNO₃ per L

(IIRC)

edit: Just in case you didn't pick it up. As stated below, you'll have to work out how many milligrams of Pb are in 0.010 mg of PbNO₃, to obtain your final answer.

[jadams]

Just remember you are calculating lead ion mass per litre, not lead nitrate.

Therefore, you must work out either moles of lead nitrate in 1L, and then multiply that molar figure by the molar mass of Lead, OR you can work out the percentage mass by composition of Lead in Lead nitrate, and multiply that by the mass of lead nitrate per litre.