Question

1. Cati moli reprezinta 280g de NaOH ?
2. Cate grame reprezinta 0.5 moli de apa?

Answer 1

1.

n = nr de moli = masa substanta / M moleculara

M naoh = 23+16+1 = 40 g/mol

n = 280 / 40 = 7 moli NaOH

2.

n = masa / M moleculara

M moleculara apa = 1 x2 + 16 = 18 g/mol

=> m = n x M = 0,5 x 18 = 9 g H2O