Medium MCQ +4 / -1 PYQ · JEE Mains 2022

$$ \begin{aligned} &\mathrm{C}(\mathrm{s})+\mathrm{O}_{2}(\mathrm{~g}) \rightarrow \mathrm{CO}_{2}(\mathrm{~g})+400 \mathrm{~kJ} \\ &\mathrm{C}(\mathrm{s})+\frac{1}{2} \mathrm{O}_{2}(\mathrm{~g}) \rightarrow \mathrm{CO}(\mathrm{g})+100 \mathrm{~kJ} \end{aligned} $$

When coal of purity 60% is allowed to burn in presence of insufficient oxygen, 60% of carbon is converted into 'CO' and the remaining is converted into '$\mathrm{CO}_{2}$'. The heat generated when $0.6 \mathrm{~kg}$ of coal is burnt is _________.

  1. A 1600 kJ
  2. B 3200 kJ
  3. C 4400 kJ
  4. D 6600 kJ Correct answer

Solution

Weight of coal $=0.6 \mathrm{~kg}=600 \mathrm{gm}$ <br/><br/>$\therefore 60 \%$ of it is carbon <br/><br/>So weight of carbon $=600 \times \frac{60}{100}=360 \mathrm{~g}$ <br/><br/>$\therefore$ moles of carbon $=\frac{360}{12}=30$ moles <br/><br/>$$ \begin{gathered} \underset{12 \text { moles }}{\mathrm{C}}+\mathrm{O}_{2} \longrightarrow \mathrm{CO}_{2} \\ \underset{\substack{18 \text { moles } \\ \text { (60\% of total Carbon })}}{\mathrm{C}}+\frac{1}{2} \mathrm{O}_{2} \longrightarrow \mathrm{CO} \end{gathered} $$ <br/><br/>$\therefore$ Heat generated $=12 \times 400+18 \times 100=6600 \mathrm{~kJ}$

About this question

Subject: Chemistry · Chapter: Some Basic Concepts of Chemistry · Topic: Mole Concept

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