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Calculati masa (g) de solutie NaOH de conentratie 20 % care reactioneaza stoechiometric cu 0.2 moliHCl. Notati ec reactiei chimice care are loc.

Răspuns :

NaOH + HCl = NaCl + H2O
Cf. ec. react. chimice:
1 mol HCl.................... 1 mol NaOH
0,2 moli...........................x 
x = 0,2 moli NaOH
M NaOH = A Na + A O+A H = 23 +16+1 = 40 
1 mol NaOH = 40 gNaOH
n = m/M, mNaOH = 0,2 .40 = 8 g NaOH
c= (md/ms).100, deci ms=md.100/c; msNaOH = 8.100/20=40 g sol.NaOH 20%