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Some Basic Concepts of Chemistry question

2021 · 25 Jul · Shift 1 · Q23
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Some Basic Concepts of Chemistry question

2021 · 25 Jul · Shift 1 · Q23

JEE MainChemistrySome Basic Concepts of ChemistryNumerical+4 / −1
Consider the complete combustion of butane, the amount of butane utilized to produce 72.0 g of water is ‾×\underline{\hspace{2cm}}\times​× 10 −-− 1 g. (in nearest integer)
Numerical answer
View written solutionFree

Correct answer: 464

  1. Write the balanced combustion reaction of butane

Butane is C4H10\mathrm{C_4H_{10}}C4​H10​. Its complete combustion is:

2C4H10+13O2→8CO2+10H2O2\mathrm{C_4H_{10}} + 13\mathrm{O_2} \rightarrow 8\mathrm{CO_2} + 10\mathrm{H_2O}2C4​H10​+13O2​→8CO2​+10H2​O

So,

2 mol butane→10 mol water2 \text{ mol butane} \rightarrow 10 \text{ mol water}2 mol butane→10 mol water

Hence,

1 mol butane→5 mol water1 \text{ mol butane} \rightarrow 5 \text{ mol water}1 mol butane→5 mol water
  1. Find moles of water formed

Given mass of water = 72.0 g72.0\,\text{g}72.0g

Molar mass of water = 18 g mol−118\,\text{g mol}^{-1}18g mol−1

Moles of water=72.018=4\text{Moles of water} = \frac{72.0}{18} = 4Moles of water=1872.0​=4
  1. Find moles of butane consumed

From stoichiometry,

1 mol butane→5 mol water1 \text{ mol butane} \rightarrow 5 \text{ mol water}1 mol butane→5 mol water

Therefore,

Moles of butane=45=0.8\text{Moles of butane} = \frac{4}{5} = 0.8Moles of butane=54​=0.8
  1. Convert moles of butane to mass

Molar mass of butane C4H10\mathrm{C_4H_{10}}C4​H10​ is:

4(12)+10(1)=48+10=58 g mol−14(12) + 10(1) = 48 + 10 = 58\,\text{g mol}^{-1}4(12)+10(1)=48+10=58g mol−1

So mass of butane used is:

0.8×58=46.4 g0.8 \times 58 = 46.4\,\text{g}0.8×58=46.4g
  1. Match with the required form

The question says the amount is:

‾×10−1 g\underline{\hspace{2cm}} \times 10^{-1} \, \text{g}​×10−1g

Now,

46.4 g=464×10−1 g46.4\,\text{g} = 464 \times 10^{-1}\,\text{g}46.4g=464×10−1g

So the required integer is:

464\boxed{464}464​
  1. Comparison with stored correct answer

Derived answer = 464464464

Stored correct answer = 464464464

They match.

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