Consider the following reaction:
PbCl2 + 2 NaOH → Pb(OH)2 + 2 NaCl
What would be the major species observed floating in solution after one mole of PbCl2 and 2 moles of NaOH are mixed in aqueous
solution?
1. Na+ ions, Cl− ions and H+ ions
2. Pb2+ ions, Cl− ions, Na+ ions and OH− ions
3. Na+ and OH− ions
4. Pb2+ ions, Cl− ions and Na+ ions
5. Pb2+ ions, Na+ ions and OH− ions
6. Cl− ions and Na+ ions
7. Pb2+ ions, Cl− ions, Na+ ions, H+ ions and OH− ions
I don't get the point of this question.
a. The word "mixed" in water...LeadII chloride is very slightly soluble, only about 11 grams/liter, so how much water was there?
b. major species OBSERVED floating in solution...I have never seen, nor know anyone who have seen ions floating "in solution". That is ridiculous.
c. Now if you added the quanities you stated, in say a liter of water, then you would have left much leadII Chloride, and much unreacted sodium hydroxide, just a tad of insoluble LeadII hydroxide, and a few sodium ions, hydroxide ions, and chloride ions. But NO ONE would see these species floating in solution. Because of the very high pH, very few H+ ions would be there.
d. Somehow, I don't get the pont of this question at all. Or the author missed the boat on proofing it.
Ditto Bob Pursley and his comments.
6
8. Juggling clowns and dancing unicorns
To determine the major species observed floating in solution after the reaction, we need to carefully analyze the balanced chemical equation:
PbCl2 + 2 NaOH → Pb(OH)2 + 2 NaCl
From the equation, we can identify the following species involved:
- PbCl2: This is lead(II) chloride, which consists of Pb2+ ions and Cl− ions.
- NaOH: This is sodium hydroxide, which dissociates in aqueous solution to form Na+ ions and OH− ions.
- Pb(OH)2: This is lead(II) hydroxide, which consists of Pb2+ ions and OH− ions.
- NaCl: This is sodium chloride, which dissociates in aqueous solution to form Na+ ions and Cl− ions.
Based on the equation, it is clear that Pb2+ ions, Cl− ions, Na+ ions, and OH− ions are present in the reaction and would, therefore, be the major species observed floating in solution.
Therefore, the correct answer is option 4: Pb2+ ions, Cl− ions, and Na+ ions.