Question

Problem 4.110 Lead glass contains 18-40% by mass of PbO (instead of CaO in regular glass). Lead glass is still used industrially, but lead crystal drinking goblets are no longer considered safe, as the lead may leach out and cause toxic responses in humans. A particular 266-g lead crystal goblet that holds 500 mL of liquid is 31 % PbO by mass, and it leaches 4.4 micrograms of lead every time it is filled. Part A How many grams of sodium sulfide would be required to decontaminate all the lead in the entire goblet? Express your answer using two significant figures.

Answer 1

m = 266 g lead crystal --> 31% of PbO

V = 500 mL

4.4 micrograms every time it is filld

a)

grams of Na2S required to decontaminate the globate

so..

1 time --> 4.4 micrograms of Pb+2 goes into solution of V = 500 mL = 0.5 L

so..

Pb+2 + Na2S --> PbS + 2Na+

1 mol of Pb+2 = 1 mol of Na2S

mol of Pb+2 = mass/MW = (4.4*10^-6)/(207.2) = 2.123552*10^-8 mol of Pb+2

so

we require

2.123552*10^-8 mol of Na2S

mass of NA2S = mol*MW = (2.123552**10^-8) * 78.0452 = 1.6573*10^-6 g of Na2S required or 1.65 micrograms