Write down the reaction equations: Cr⇒CrCl₃⇒Cr (OH) ₃⇒Cr (SO₄) ₃ Ba⇒BaCl₂⇒Ba (NO₃) ₂⇒Ba (NO₂) ₂⇒Ba (OH) ₂

We compose the reaction equations:
2Сr + 3Cl2 = 2CrCl3 – the reaction of the compound;
CrCl3 + 3NaOH = Cr (OH) 3 + 3NaCl – ion exchange reaction;
2Cr (OH) 3 + 3H2SO4 = Cr2 (SO4) 3 + 6H2O – ion exchange reaction;
In the chain of transformations, the synthesis of chromium salts, which are used in the production of dyes, has been carried out.
We compose the equations for the synthesis of barium compounds:
Ba + 2HCl = BaCl2 + H2 – redox reaction;
BaCl2 + 2HNO3 = Ba (NO3) 2 + 2HCl – ion exchange reaction;
Ba (NO3) 2 + 2NaOH = Ba (OH) 2 + 2HNO3 – ion exchange reaction;
Barium salts are used in X-ray studies in medicine.