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  • On complete combustion of an organic compound gave <img alt="0.20 \mathrm{~g}" src="h

On complete combustion 0.30 \mathrm{~g} of an organic compound gave 0.20 \mathrm{~g} of carbon dioxide and 0.10 \mathrm{~g} of water. The percentage of carbon in the given organic compound is ______________.(Nearest Integer)

Option: 1

18


Option: 2

-


Option: 3

-


Option: 4

-


Answers (1)

best_answer

Combustion Reaction of given organic compound-

Balanced Reaction
\mathrm{C_{x}H_{y}O_{z}+\left ( x+\frac{y}{4}-\frac{z}{2} \right )O_{2}\rightarrow xCO_{2}+\frac{y}{2}\, H_{2}O}

  \mathrm{ 0.3\, g}                                                       \mathrm{ 0.2\, g}         \mathrm{ 0.1\, g}

To find the percentage of carbon in given organic compound i.e. \mathrm{C_{x}H_{y}O_{z}}, we need to find values of \mathrm{x,y,z.}

\mathrm{\frac{^{n } CO_{2}}{^{n }H_{2}O}=\frac{x}{y/2}=\frac{0.2 / 44}{0.1 / 18} \Rightarrow \frac{2 x}{y}=\frac{0.2 \times 18}{4.4}}

\mathrm{\Rightarrow 2 \frac{x}{y}=\frac{36}{44} \Rightarrow \frac{x}{y}=\frac{9}{2 2} \Rightarrow x=\frac{9}{22} y\, -(1)}

Now,

\mathrm{\frac{^{n }C_{x} H_{y} O_{z}}{^{n }CO_{2} }=\frac{1}{x} }

\mathrm{ \Rightarrow \frac{0.3}{(12 x+y+16z)} \times \frac{(44) }{0.2 }=\frac{1}{x} }

\mathrm{\Rightarrow 132 x=24 x+2 y+32z }

\mathrm{\Rightarrow \quad 54 x=y+16z }

now putting the value of '\mathrm{x }' from equation (1) , we get

\mathrm{ 54\left(\frac{9}{22} y\right)=y+16z }

\mathrm{\Rightarrow z= \frac{29}{22} y \quad -(2)}  

\therefore We have -
       \mathrm{x= \frac{9}{22}\, y,\; z= \frac{29}{22}\, y}

Formula , \mathrm{C_{x}H_{y}O_{z}} can be written as \mathrm{C_{\frac{9y}{22}}\, H_{y}\, O_{\frac{29y}{22}}

which can be simplified into \mathrm{ C_{9}H_{22}O_{29}}

\mathrm{%\: of\: carbon\; in\: C_{9}H_{22}O_{29}= \frac{mass\, of\; C}{Total\; mass}\times 100}

                                                      \mathrm{= \frac{12\times 9}{\left ( 12\times 9+22+16\times 29 \right )}\times 100}
                                                        \mathrm{= \frac{108}{594}\times 100}
                                                         \mathrm{= 18.18 \, %}

Nearest integer is 18 which is the answer

Posted by

Pankaj Sanodiya

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