Question

O cantitate de 5g oxid de magneziu reactioneaza cu o solutie de acid sulfuric .Calculati :

A) masa solutiei de acid sulfuric de concentratie 86%

B) Masa de sulfat de calciu obtinut de puritate 98%

Answer 1

M,MgO= 40g/mol;   M,H2SO4= 98g/mol;    M,MgSO4= 120g/mol
-calculez moliMg din masa data
n(niu)= 5g/40g/mol= 0,125molMg
- din ecuatie scot moli acid si moli sare
1mol     1mol         1mol
MgO +H2SO4---> MgSO4 +H2O
0,125....0,125.......0,125
-calculez masa acid
m= n,molx Mg/mol----> m= 0,125molx98g/mol=12,25gH2SO4
-calculez masa de solutie ce contine dizolvata masa de acid calculata
c/100=md/ms
86/100= 12,25/ms............................calculeaza ms!
-calculez masa de sulfat de magneziu
m= 0,125gx120g/mol=15gMgSO4  PUR
-calculez masa de sulfat de magneziu care contine si impuritati
p/100= m,pur/m,impur
98/100= 15/m,impur...........................calculeaza m,impur !