CН4 → C2H2 → C2H4→ C2H5ОН → СН3-СН=О → СН3-СООН

2CH4 = C2H2 + 3H2

C2H2 + H2 = C2H4

C2H4 + H2O = C2H5OH

C2H5OH + CuO = CH3CHO + Cu + H2O

CH3CHO + Br2 + H2O = CH3COOH + 2HBr

cu2o (i)

cuo ( ii )

feo ( ii)

fe2o3 ( iii) 

mn2o3 (iii)

mn2o7 (vii)

k3po4 + h2o = k2hpo4 + koh;

3k+po4+h2o=3k+hpo4+oh

po4+h2o=hpo4+oh

2k+hpo4+h2o=2k+oh+h2po4

hpo4+h2o=oh+h2po4

подставь заряда ионов