Question

A forensic scientist analyzes a sample for sodium arsenate, Na 3 AsO 4 (s), a source of arsenic. Calculate

the percentage composition of sodium arsenate.

Answer 1

Mr(Na) = 23 g/mol

Mr(As) = 75 g/mol

Mr(O) = 16 g/mol

Mr(Na₃AsO₄) = 208 g/mol

$Na= \frac{23*3}{208}*100= 33,17$ %

$As= \frac {75}{208}*100= 36,06$ %

$O= \frac {16*4}{208}*100= 30,77$ %