Question

Determina masa de hidrogen din :
a)36 g apa
b)3,4 kg amoniac
c)6,023 x 10 la puterea 22 molecule acid clorhidric
d) 2 moli hidroxid de sodiu
e) 0,1 kmoli acid sulfuric

Answer 1

a.

m (H2O) = 36 g

M (H2O) = (2×1)+16 = 18 g/mol

18 g H2O ....... 2 g H2

36 g H2O ........ x x = (2×36)/18 = 4 g H2

b.

m (NH3) = 3.4 kg = 3400 g

M (NH3) = 14 + (3×1) = 17 g/mol

17 g NH3 ........... 3 g H2

3400 g NH3 ............ x

x = (3×3400)/17 = 600 g H2 = 0.6 kg H2

c.

NA = 6.023×10^22 molec. HCl

M (HCl) = 1 + 35.5 = 36.5 g/mol

1 mol ...... NA molecule (NA = 6.023×10^22)

1 mol HCl ........ 36.5 g ........ 1 g H2

m (H2) = 1 g

d.

n (NaOH) = 2 moli

M (NaOH) = 23 + 16 + 1 = 40 g /mol

n = m/M => m = n×M = 2 × 40 = 80 g NaOH

40 g NaOH .......... 1 g H2

80 g NaOH ........... x x = (1×80)/40 = 2 g H2

e.

n (H2SO4) = 0.1 kmoli = 100 moli

M (H2SO4) = (2×1)+32+(4×16) = 98 g/mol

n = m/M => m = n × M = 100 × 98 = 9800 g H2SO4 = 9.8 Kg H2SO4

98 g H2SO4 ......... 2 g H2

9.8 kg H2SO4 .......... x

x = (2×9.8)/98 = 0.2 kg H2 = 200 g H2