Question

1. 19,6 g MnCl3 sunt dizolvate in 2kg solutie. Calculati masa procentuala a solutiei. Masa atomica Mn=55 si masa atomica Cl=35,5g
2. Calculati concentratia procentuala a solutiei obtinute prin dizolvarea a 2,5 NaCl in 40,5 g H2O
3. Ce cantitate de NaOH este necesara pentru a prepara 800g solutie de 40%
Vreau urgent !!!!!!!!!!! Dau Coroana !!!!!!!!!

Answer 1

1. md = 19,6g , ms = 2 kg = 2000g

c% = mdx100/ms = 19,6x100/2000 = 0,98%

2.

md = 2,5g , m.apa = 40,5g

stim ca ms = md+m.apa = 2,5+40,5 = 43g sol.

c% = mdx100/ms = 2,5x100/43 = 5,82%

3.

ms = 800g, c%= 40%

c% = mdx100/ms

=> md = msxc%/100 = 800x40/100 = 320 g NaOH