Question

la oxidul de aluminiu cu masa de 5,1 g a fost adaugata o solutie ce contine acid azotic cu m 25,2 g.calculeazq masa sarii....urgent va rog:(

Answer 1

Se da:

m ( Al2O3 )=5,1 g

m (HNO3)=25,2 g

m ( sarii) - ?

                                Re-re:

      5,1 g                              x

    Al2O3 +6 HNO3 ==>2Al (NO3)3 +3 H2O

   1 mol      6mol              2mol           3mol

M(Al2O3)= 27 g/mol x2   +  3x 16 g/mol = 54 g/mol + 48 g/mol = 102  g/mol

v=m/M

v ( Al2O3) = 5,1 g / 102 g/mol = 0,05 mol

v (Al(NO3)3)=v(Al2O3) x 2 mol / 1 mol = 0,05 mol x2=0,1 mol

M (Al (NO3)3 ) = 27 g/mol + 3x 14g/mol + 3x3x16 g/mol

=> 27 g/mol + 42 g/mol + 144 g/mol = 213 g/mol

m=v x M

m (Al (NO3)3 ) = 0,1 mol  x 213 g/mol = 21,3g

                     R-s:  m (Al (NO3)3 ) = 21,3 g