Question

Calculați cantitatea de acid fosforic care contine 640g O

Answer 1

Acidul fosforic: H3PO4

$M_{H3PO4}=3*1+31+4*16=98 \ \ \ =\ \textgreater \ \ \ u_{H3PO4}=98 \ g/mol$

(Am notat cu M masa moleculara si cu u masa molara)

Aplicam regula de 3 simpla:

98 g H3PO4................4*16 g O
       m..........................640 g O

$m= \dfrac{640*98}{4*16}=980\ g\ H3PO4$

In moli:

$n_{H3PO4}= \dfrac{980}{98}=10 \ moli$