Question

When 1 mL of 0.1 M barium chloride (BaCl2) solution and one drop of 1 M potassium chromate of (K2CrO4) is added, the solution turns a light yellow and cloudy,

Write a net ionic equation for what occurs.

K2CrO4(aq) + BaCl2(aq)→BaCrO4(s) + 2KCl(aq)

Total ionic: 2K+(aq) + CrO42-(aq) + Ba2+(aq) + 2Cl-(aq)→BaCrO4(s) + 2K+(aq) + 2Cl-(aq)

Net ionic: Ba2+(aq) + CrO42-(aq)→BaCrO4(s)

Which way will the equilibrium shift in the precipitation reaction above?

which species would react if hydrochloric acid is added. Which way will the equilibrium shift in the precipitation reaction above

Answer 1

BaCl2 + K2CrO4 --> BaCrO4 + 2 KCl

It’s a double replacement reaction, but same is not at the equilibrium)

BaCrO4 <-> Ba2+ + CrO4 2- eq.1 ( let us assume equililibrium 1)

In water,

2 CrO4 2− + 2 H+ <-> Cr2O7 2− + H2O second equilibrium. Eq.2

If you add HCl, that's the same thing as adding H+ ions and also Cl- ions, but those are not important since they are not involved in the two equilibrium reactions.

Adding H+ causes the equilibrium to shift to the right in eq.2. This means that CrO4 2- would decrease. This decrease affects eq. 1. To compensate for the decrease, eq.1 would shift to the right, and the precipitate would dissolve.

Therefore, the equilibrium concerning the precipitate will shift to the right, and the precipitate will dissolve.