Question

Natriu reactioneaza cu H2S ( c=20%) . Volumul de hidrogen degajat este de 44,8l . Calculati masa solutie de H2S utilizata . ( As=32)

Answer 1

2 Na + H2S = Na2S + H2
V c.n. = 22,4 l/mol
M H2S = 2+32 = 34 g/mol
34 g H2S........22,4 l H2
x.....................44,8 l H2
x = 68 g H2S
c = md*100/ms
ms = md*100/c = 68/20 * 100 = 340 g soluție

Answer 2

............x........................44,8 l
2Na+H2S-->Na2S+H2
............34g...................22,4 l
M(H2S)=2Ah+As=2+32=34g
$x = \frac{34 \times 44.8}{22.4} = 68 \: g$
$c = \frac{md}{ms} \times 100 \\ ms = \frac{md \times 100}{c} \\ ms = \frac{68 \times 100}{20} = 340 \: g$