2CrO4^2- + 2H^+ ⇌ Cr2O7^2- + H2O color

Consider the chromate/dichromate ion equilibrium:

2CrO4^2-(aq) + 2H^+(aq) ⇌ Cr2O7^2-(aq) + H2O(l)

yellow ............................................................. orange

a) What color will a solution be,

if it contains only K2CrO4?

b) Add H2SO4 to the K2CrO4 solution.

H2SO4 is a strong acid that dissociates to increase [H^+]

in the solution according to the following reactions.

H2SO4(aq) → H^+(aq) + HSO4^-(aq)

HSO4^-(aq) ⇌ H^+(aq) + SO4^2-(aq)

How does increasing the concentration of H^+

affect the chromate/dichromate equilibrium position?

What color will the solution be after we add H2SO4?

c) When we add NaOH to the solution,

it dissociates to form Na^+ and OH^-.

What does OH^- react with in the solution?

How does this reaction affect

the chromate/dichromate equilibrium position?

What color will the solution be?

a) K2CrO4의 색깔 = CrO4^2-(aq)의 색깔 이므로,

용액의 색깔은 yellow.

[ https://en.wikipedia.org/wiki/Potassium_chromate ]

b) 산(H^+)을 가하면,

반응물인 H^+(aq)가 증가하므로,

르 샤틀리에의 원리에 따라,

정반응이 일어나므로,

용액의 색깔은 orange.

( Cr2O7^2-(aq)의 색깔 )

c) 염기(OH^-)를 가하면,

H^+(aq) + OH^-(aq) → H2O(l) 반응에 의해,

반응물인 H^+(aq)가 감소하므로,

르 샤틀리에의 원리에 따라,

역반응이 일어나므로,

용액의 색깔은 yellow.

( CrO4^2-(aq)의 색깔 )

[키워드] K2CrO4 color 기준, K2CrO4의 색깔 기준