# Molecular weight of lead(ii) nitrate Pb(NO_3)_2

Hello everyone
I am trying to solve the following question from the book Analytical Chemistry 7th edition by Gard D. Christian - Page 164 Example 5.17

My problem is when I calculate the molecular weight of Pb(NO_3)_2 I get 331.2 g/mol but in the book they get 283.2 g/mol . Could you explain to me where they get this number. So instead of getting 0.137 g as last result, I get 0.16 g.

Also googling the question always gets me the same solution.

Borek
Mentor
when I calculate the molecular weight of Pb(NO_3)_2 I get 331.2 g/mol

That's what I got as well, book is wrong.

HAYAO, jim mcnamara and Paul Black
First time I see an error in a book.
So in that case all the internet pages that have the same question+solution made the same mistake. Do they just copy past ?

Borek
Mentor
First time I see an error in a book.

Lucky you.

So in that case all the internet pages that have the same question+solution made the same mistake. Do they just copy past ?

Apparently.

The molar mass they used is off by 48, which is exactly three oxygen atoms, as if they had calculated molar mass for PbN2O3.

HAYAO and Paul Black