When mixed, solutions of silver nitrate, AgNO 3, and sodium phosphate, Na 3PO 4, will form a precipitate of silver phosphate, Ag 3PO 4. The balanced equation is 3AgNO 3( aq) + Na 3PO 4( aq) ? Ag 3PO 4(s) + 3NaNO 3( aq) Which of the following statements regarding this reaction is incorrect?
3 moles of Ag 3PO 4 should form when 3 moles of Na 3PO 4 react with sufficient AgNO 3.
2 moles of Na 3PO 4 will react with 6 moles of AgNO 3.
6 moles of AgNO 3 will react with 2 moles of Na 3PO 4.
9 moles of AgNO 3 should react to form 2 moles of Ag 3PO 4, given sufficient Na 3PO 4.
1.5 moles of NaNO 3 should form when 0.5 mole of Na 3PO 4 reacts with sufficient AgNO 3.
The correct answer and explanation is:
Incorrect Statement:
“3 moles of Ag₃PO₄ should form when 3 moles of Na₃PO₄ react with sufficient AgNO₃.”
Explanation:
To determine why this statement is incorrect, we need to analyze the balanced chemical equation:
[
3AgNO₃(aq) + Na₃PO₄(aq) \rightarrow Ag₃PO₄(s) + 3NaNO₃(aq)
]
This equation shows that 1 mole of Na₃PO₄ reacts with 3 moles of AgNO₃ to form 1 mole of Ag₃PO₄ and 3 moles of NaNO₃.
Now, let’s apply this stoichiometric relationship to the incorrect statement:
- The statement suggests that 3 moles of Na₃PO₄ would produce 3 moles of Ag₃PO₄.
- According to the balanced equation, 1 mole of Na₃PO₄ forms 1 mole of Ag₃PO₄, so 3 moles of Na₃PO₄ should indeed produce 3 moles of Ag₃PO₄.
At first glance, this statement seems correct, but the mistake lies in not checking if there is sufficient AgNO₃.
For 3 moles of Na₃PO₄ to fully react, we need:
[
3 \times 3 = 9 \text{ moles of } AgNO₃
]
However, the statement does not specify whether there is enough AgNO₃. It assumes Ag₃PO₄ will form regardless of the limiting reagent, which could be misleading. If there is insufficient AgNO₃, less than 3 moles of Ag₃PO₄ would actually form.
Thus, the statement is incorrect because it does not account for the need for 9 moles of AgNO₃ as a reactant for 3 moles of Na₃PO₄.