nu e bine ,dar e bine ca ai incercat !!
-calculez masa de NaOH, din solutia data
c=mdx100/ms---> md= 20x250/100g= 50gNaOH
-calculez masa de sulfat de sodiu, din ecuatia chimica, stiind M,NaOH= 40g/mol, M,Na2SO4=142g/mol
2mol...........................................1,mol sau, in grame
2NaOH + H2SO4-------> Na2SO4 + 2H2O
2x40g........................................142g
59g................................................x................................calculeaza !!!!!