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Current Question (ID: 8263)

Question:

$\text{The bond energies of C} \equiv \text{C, C-H, H-H, and C=C are 198, 98, 103 and 145 kcal respectively.}$ $\text{The enthalpy change of the reaction HC} \equiv \text{CH + H}_2 \rightarrow \text{C}_2\text{H}_4 \text{ would be-}$

Options:

1. $48 \text{ kcal}$
2. $96 \text{ kcal}$
3. $-40 \text{ kcal}$
4. $-152 \text{ kcal}$

Solution:

$\text{Hint: } \Delta\text{H}_\text{r} = \text{energy of the bond being broken} - \text{energy of the bonds being formed}$ $\text{Step 1:}$ $\text{The given values are as follows:}$ $\text{B. E}_{\text{C}\equiv\text{C}} = 198 \text{ kcal}$ $\text{B. E}_{\text{C-H}} = 98 \text{ kcal}$ $\text{B. E}_{\text{H-H}} = 103 \text{ kcal}$ $\text{B. E}_{\text{C=C}} = 145 \text{ kcal}$ $\text{Step 2:}$ $\Delta\text{H}_\text{r} = \text{energy of the bond being broken} - \text{energy of the bonds being formed}$ $\Delta\text{H}_\text{r} = [\text{B. E}_{\text{C}\equiv\text{C}} + (2 \times \text{B. E}_{\text{C-H}}) + \text{B. E}_{\text{H-H}}] - [\text{B. E}_{\text{C=C}} + (4 \times \text{B. E}_{\text{C-H}})]$ $\Delta\text{H}_\text{r} = [198 + (2 \times 98) + 103] - [145 + (4 \times 98)]$ $\Delta\text{H}_\text{r} = -40 \text{ kcal}$

Import JSON File

Upload a JSON file containing LaTeX/MathJax formatted question, options, and solution.

Expected JSON Format:

{
  "question": "The mass of carbon present in 0.5 mole of $\\mathrm{K}_4[\\mathrm{Fe(CN)}_6]$ is:",
  "options": [
    {
      "id": 1,
      "text": "1.8 g"
    },
    {
      "id": 2,
      "text": "18 g"
    },
    {
      "id": 3,
      "text": "3.6 g"
    },
    {
      "id": 4,
      "text": "36 g"
    }
  ],
  "solution": "\\begin{align}\n&\\text{Hint: Mole concept}\\\\\n&1 \\text{ mole of } \\mathrm{K}_4[\\mathrm{Fe(CN)}_6] = 6 \\text{ moles of carbon atom}\\\\\n&0.5 \\text{ mole of } \\mathrm{K}_4[\\mathrm{Fe(CN)}_6] = 6 \\times 0.5 \\text{ mol} = 3 \\text{ mol}\\\\\n&1 \\text{ mol of carbon} = 12 \\text{ g}\\\\\n&3 \\text{ mol carbon} = 12 \\times 3 = 36 \\text{ g}\\\\\n&\\text{Hence, 36 g mass of carbon present in 0.5 mole of } \\mathrm{K}_4[\\mathrm{Fe(CN)}_6].\n\\end{align}",
  "correct_answer": 4
}