Question

Am nevoie urgentt!!! Va mulțumesc

Answer 1

VII.

Vs.HCl = 200 mL = 0,2 L

Cm.HCl = 2M

Cm = niu/Vs => niu = CmxVs = 2x0,2 = 0,4 moli HCl

 mp  g       0,4 moli

CaCO3  +  2HCl --> CaCl2 + H2O + CO2

 100            2

=> mp = 100x0,4/2 = 20 g CaCO3 pur

25 g CaCO3 impur .......................... 100%

20 g CaCO3 pur ................................ p%= 80%

VIII.

32,5g   md g                           m g

   Zn + 2NaOH + 2H2O = Na2Zn(OH)4 + H2

   65      2x40                            179

=> md = 32,5x2x40/65 = 40 g NaOH

c%.NaOH= 20%

c% = mdx100/ms => ms = mdx100/c% = 40x100/20 = 200 g sol. NaOH

=> m = 32,5x179/65 = 89,5 g sare complexa