2 C6H5-OH + 2 HNO3 = o-nitrofenol + p-nitrofenol + 2 H2O
M HNO3 = 63 g/mol
M nitrofenol = 139 g/mol
2*63 g HNO3...........2*139 g amestec nitrofenoli
x...............................2,5 g amestec nitrofenoli
x = 1,133 g HNO3
c = md*100/ms
ms = 1,1333/30*100 = 3,7666 g soluție HNO3 30%