Question

intr-un pahar se afa 20g saramura de concentratie 40% . calculeaza numarul de molecule existent in solutia din pahar

Answer 1

40/100=m,diz/20     ---> m,diz=8gNaCl
                                      m,sol= 8gNa Cl + m,apa---> m,apa= 20-8 --->12gH20
Masa molara pentru Na Cl :μ= 23gNa +35,5gCl---->58,5g/mol
Nr moli NaCl  : niu= 8g/58,5g/mol   =>0,14mol NaCl
Masa molara pentru H2O:  μ= 2X1gH +16gO => 18g/mol
Nr.mol H2o:   niu=12g/18g/mol=>0,66mol H20
Total moli:0,8 moli
1 mol   are 6,o23x10²³molecule
o,8moli          N=0,8x6,023x1o²³molecule