Homework Help

1. Lead is a poisonous metal that especially affects children because they retain a...

user profile pic

ashweee09 | eNotes Newbie

Posted April 21, 2013 at 4:55 AM via web

dislike 0 like
1.
Lead is a poisonous metal that especially affects children because they retain a larger fraction of lead than adults do. Lead levels of 0.250 ppm in a child cause delayed cognitive development. How many moles of lead present in 1.00 g of a child’s blood would 0.250 ppm represent?

1 Answer | Add Yours

user profile pic

llltkl | College Teacher | Valedictorian

Posted April 21, 2013 at 8:06 AM (Answer #1)

dislike 1 like

PPM is a unit of concentration used to express very low concentrations. It means parts per million, i.e. parts of a contaminant present per million (10˄6) parts of a solution. 0.250 ppm of lead in blood means that  0.250 parts of lead present in one million parts of the child's blood sample.

In units of grams, 1000000g blood sample contains 0.25g lead.

So, 1 g blood sample should contain 0.25/1000000 g of lead = 0.25/(1000000×207.2)g of lead = 1.207 ×10˄-9 moles of lead = 1.207 nanomoles of lead (atomic mass of lead is 207.2).

Sources:

Join to answer this question

Join a community of thousands of dedicated teachers and students.

Join eNotes