Question

O cantitate de 500g solutie NaOH de concentratie procentuala 20%se trateaza cu 500g solutie HCl de concentratie 10%.
Determinati cantitatea de substanta luata in exces si culoarea turnesolului in solutia obtinuta.

Answer 1

md NaOH = 500*20/100 = 100 g
md HCl = 10*500/100 = 50 g
HCl + NaOH ---> NaCl + H2O
36,5 g HCl........40 g NaOH
x g HCl.............100 g NaOH      x = 91,25 g HCl
36,5 g HCl.........40 g NaOH
50 g HCl...............x g NaOH      x = 57,8 g NaOH
91,25 > 57,8 => exces de HCl => turnesolul in mediu acid are culoarea rosie