MCQEasyJEE 2023Stoichiometry & Calculations

JEE Chemistry 2023 Question with Solution

One mole of P4P_4 reacts with 88 moles SOCl2SOCl_2 to give 44 moles of AA, xx mole of SO2SO_2 and 22 moles of BB. A, B and xx respectively are _____.

  • A

    POCl3POCl_3, S2Cl2S_2Cl_2 and 44

  • B

    POCl3POCl_3, S2Cl2S_2Cl_2 and 22

  • C

    PCl3PCl_3, S2Cl2S_2Cl_2 and 44

  • D

    PCl3PCl_3, S2Cl2S_2Cl_2 and 22

Answer

Correct answer:C

Step-by-step solution

Standard Method

Given: One mole of P4P_4 reacts with 88 moles of SOCl2SOCl_2 to form 44 moles of AA, xx mole of SO2SO_2 and 22 moles of BB.

Find: The identities of AA, BB and the value of xx.

The balanced chemical equation given in the solution is:

P4+8SOCl24PCl3+4SO2+2S2Cl2P_4 + 8SOCl_2 \rightarrow 4PCl_3 + 4SO_2 + 2S_2Cl_2

From this equation:

  • A=PCl3A = PCl_3
  • B=S2Cl2B = S_2Cl_2
  • x=4x = 4

Therefore, the correct option is C.

Match Products with Stoichiometric Coefficients

Given: The reaction of P4P_4 with SOCl2SOCl_2.

Find: Which product corresponds to AA, which corresponds to BB, and how many moles of SO2SO_2 are formed.

Using the balanced reaction:

P4+8SOCl24PCl3+4SO2+2S2Cl2P_4 + 8SOCl_2 \rightarrow 4PCl_3 + 4SO_2 + 2S_2Cl_2

Compare this directly with the form stated in the question:

P4+8SOCl24A+xSO2+2BP_4 + 8SOCl_2 \rightarrow 4A + xSO_2 + 2B

Matching coefficients and products term by term:

4A=4PCl3A=PCl34A = 4PCl_3 \Rightarrow A = PCl_3 2B=2S2Cl2B=S2Cl22B = 2S_2Cl_2 \Rightarrow B = S_2Cl_2 xSO2=4SO2x=4xSO_2 = 4SO_2 \Rightarrow x = 4

Hence, A=PCl3A = PCl_3, B=S2Cl2B = S_2Cl_2, and x=4x = 4. The correct option is C.

The solution's lists answer key as option (1), but the extracted solution clearly concludes option C. Since the solution is the primary source, C is taken as correct.

Common mistakes

  • Taking POCl3POCl_3 as product AA by recalling a different phosphorus oxychloride reaction. This is incorrect because the balanced equation provided here explicitly forms PCl3PCl_3. Always identify products from the given balanced reaction, not from memory of another reaction.

  • Matching BB with the wrong sulfur chloride species. This is incorrect because the coefficient 22 in the balanced equation corresponds to 2S2Cl22S_2Cl_2. Compare the question format with the balanced equation term by term.

  • Missing the stoichiometric coefficient of SO2SO_2 and writing x=2x = 2. This is incorrect because the balanced equation shows 4SO24SO_2. Read the product side carefully before assigning xx.

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