Video: Identifying the Observations in Response to the Mixing of AgMnO₄ and NaMnO₄ in Water in a Set of Observations

Consider the following substances: NaMnO₄, a soluble purple solid, AgMnO₄, an insoluble purple solid, NaCl, a soluble white solid, AgCl, an insoluble white solid. Which of the following would be observed when 2.0 mol of AgMnO₄ and 1.0 mol of NaMnO₄ are mixed in 1 L of water? [A] Purple solid and colorless solution [B] Purple solid and purple solution [C] White solid and colorless solution [D] No solid and purple solution [E] No solid and colorless solution

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Video Transcript

Consider the following substances. NaMnO₄, a soluble purple solid; AgMnO₄, an insoluble purple solid; NaCl, a soluble white solid; AgCl, an insoluble white solid. Which of the following would be observed when 2.0 moles of AgMnO₄ and 1.0 moles of NaMnO₄ are mixed in one litre of water? A) Purple solid and colorless solution, B) Purple solid and purple solution, C) White solid and colorless solution, D) No solid and purple solution, or E) No solid and colorless solution.

Our subject is the combination of silver permanganate and sodium permanganate. We’ve been told that AgMnO₄, silver permanganate, is an insoluble purple solid, while sodium permanganate is a soluble purple solid. When the solvent isn’t stated, we assume that soluble or insoluble refer to solubility in water. So, sodium permanganate dissolves in water, while silver permanganate would simply sink to the bottom. These two compounds have exactly the same anion, and the sodium and silver ions are very stable in each other’s company. So, they don’t react.

So, let’s think what’s going to happen when we add the solid powders to water. Our silver permanganate would simply fall to bottom, creating a pretty purple pile. Meanwhile, our sodium permanganate would dissolve quickly into the water, turning it a bright purple. Therefore, of the five options given, the one that would be observed when we mix our two moles of silver permanganate and one mole of sodium permanganate in one litre of water would be purple solid and purple solution.

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