When sodium hydroxide (NaOH) is added to the equilibrium solution containing chromate ions, the solution will turn from yellow to orange, indicating a shift in the equilibrium position toward the production of dichromate ions (Cr₂O₇²⁻). On the molecular level, the increase in hydroxide ions (OH⁻) from the NaOH reacts with the hydrogen ions (H⁺) present in the equilibrium, reducing their concentration, which shifts the equilibrium to the right to produce more Cr₂O₇²⁻ ions, resulting in the observed color change from yellow to orange.
Chromate ions react according to the following equation, where the left side of the reaction is yellow and the right side is orange.CrO2−4 +2H ⇌ Cr2O−27 + H2O A student adds sodium hydroxide (NaOH) to the solution at equilibrium. In one to two sentences, describe a change the student will be able to see and explain the changes to the solution on the molecular level.
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