Q151CP - Chemistry: Molecular Nature Of Matter And Change

Question

Nitrogen monoxide ($\mathbf{NO}$ ) is a bioactive molecule in the blood. Low   concentrations cause respiratory distress and the formation of blood clots. Doctors prescribe nitroglycerin,${\mathbf{C}}_{\mathbf{3}}{\mathbf{H}}_{\mathbf{5}}{\mathbf{N}}_{\mathbf{3}}{\mathbf{O}}_{\mathbf{9}}$ , and isoamyl nitrate,${\mathbf{\left(}{\mathbf{CH}}_{\mathbf{3}}\mathbf{\right)}}_{\mathbf{2}}{\mathbf{CHCH}}_2{\mathbf{CH}}_{\mathbf{2}}{\mathbf{ONO}}_{\mathbf{2}}$ , to increase $\mathbf{NO}$ . If each compound releases one molecule $\mathbf{NO}$  per atom  , calculate the mass per cent of $\mathbf{NO}$ each medicine.

Step-by-Step Solution

Answer

The mass percentage of NO released can be found $\mathbf{39}\mathbf{.}\mathbf{65}\mathbf{\%}$ for${\mathbf{C}}_{\mathbf{3}}{\mathbf{H}}_{\mathbf{5}}{\mathbf{N}}_{\mathbf{3}}{\mathbf{O}}_{\mathbf{9}}$ and$\mathbf{22}\mathbf{.}\mathbf{57}\mathbf{\%}$ for ${\mathbf{\left(}{\mathbf{CH}}_{\mathbf{3}}\mathbf{\right)}}_{\mathbf{2}}{\mathbf{CHCH}}_2{\mathbf{CH}}_{\mathbf{2}}{\mathbf{ONO}}_{\mathbf{2}}$ 

Step 1: Calculating the molar mass of both the medicines

 

For nitroglycerin (${\mathbf{C}}_{\mathbf{3}}{\mathbf{H}}_{\mathbf{5}}{\mathbf{N}}_{\mathbf{3}}{\mathbf{O}}_{\mathbf{9}}$ ) mass can be calculated by adding atomic masses of each and every element: 

 $$\begin{gathered} \mathbf{Molecular}\mathbf{ }\mathbf{mass}\mathbf{ }\mathbf{of}\mathbf{ }{\mathbf{C}}_{\mathbf{3}}{\mathbf{H}}_{\mathbf{5}}{\mathbf{N}}_{\mathbf{3}}{\mathbf{O}}_{\mathbf{9}}\mathbf{=}\mathbf{12}\mathbf{\times }\mathbf{3}\mathbf{+}\mathbf{1}\mathbf{\times }\mathbf{5}\mathbf{+}\mathbf{14}\mathbf{\times }\mathbf{3}\mathbf{+}\mathbf{9}\mathbf{\times }\mathbf{16} \\ \mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{=}\mathbf{227}\mathbf{ }\mathbf{g}\mathbf{/}\mathbf{ }\mathbf{mol} \end{gathered}$$

 

Likewise, isoamyl nitrate (${\mathbf{\left(}{\mathbf{CH}}_{\mathbf{3}}\mathbf{\right)}}_{\mathbf{2}}{\mathbf{CHCH}}_2{\mathbf{CH}}_{\mathbf{2}}{\mathbf{ONO}}_{\mathbf{2}}$ ) mass can be calculated as:

 $$\begin{gathered} \mathbf{Molecular}\mathbf{ }\mathbf{mass}\mathbf{ }\mathbf{of}\mathbf{ }{\mathbf{\left(}{\mathbf{CH}}_{\mathbf{3}}\mathbf{\right)}}_{\mathbf{2}}\mathbf{ }{\mathbf{CHCH}}_2{\mathbf{CH}}_{\mathbf{2}}{\mathbf{ONO}}_{\mathbf{2}}\mathbf{=}\mathbf{12}\mathbf{\times }\mathbf{5}\mathbf{+}\mathbf{1}\mathbf{\times }\mathbf{11}\mathbf{+}\mathbf{14}\mathbf{+}\mathbf{3}\mathbf{\times }\mathbf{16} \\ \mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{=}\mathbf{133}\mathbf{g}\mathbf{/}\mathbf{mol} \end{gathered}$$

 

Step:2Calculating the mass percentage for nitroglycerin (C 3 H 5 N 3 O 9 )

There are three nitrogen atoms in the nitroglycerin molecule. There are 3 moles of NO which is released per mole. The molecular mass of NO is 30 g/mol. The mass of released NO can be denoted as,

 $$\begin{gathered} \mathbf{Mass}\mathbf{ }\mathbf{of}\mathbf{ }\mathbf{NO}\mathbf{ }\mathbf{released}\mathbf{ }\mathbf{mole}\mathbf{ }\mathbf{of}\mathbf{ }\mathbf{nitroglycerin}\mathbf{=}\mathbf{3}\mathbf{mol}\mathbf{\times }\mathbf{30}\frac{\mathbf{g}}{\mathbf{mol}} \\ \mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{=}\mathbf{90}\mathbf{ }\mathbf{g} \end{gathered}$$

The mass percent can be calculated as,

 $$\begin{gathered} \mathbf{Mass}\mathbf{ }\mathbf{\%}\mathbf{\left(}\mathbf{NO}\mathbf{\right)}\mathbf{=}\frac{\mathbf{90}\mathbf{g}}{\mathbf{227}\mathbf{ }\mathbf{g}}\mathbf{\times }\mathbf{100}\mathbf{\%} \\ \mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{=}\mathbf{39}\mathbf{.}\mathbf{65}\mathbf{\%} \end{gathered}$$

The mass percentage of NO released per mole of nitroglycerin (${\mathbf{C}}_{\mathbf{3}}{\mathbf{H}}_{\mathbf{5}}{\mathbf{N}}_{\mathbf{3}}{\mathbf{O}}_{\mathbf{9}}$ ) is $\mathbf{39}\mathbf{.}\mathbf{65}\mathbf{\%}$

Step 2: Calculating the mass percentage for isoamyl nitrate ((CH 3 ) 2 CHCH 2 CH 2 ONO 2 )

There is 1 nitrogen atom in each molecule of isoamyl nitrite. So, 1 mole of NO will be released per mole. The molecular mass of NO is 30 g/mol. The mass of released NO will be 30 g.

The mass percent can be denoted as,

 $$\begin{gathered} \mathbf{Mass}\mathbf{\%}\mathbf{\left(}\mathbf{NO}\mathbf{\right)}\mathbf{=}\frac{\mathbf{30}\mathbf{g}}{\mathbf{133}\mathbf{g}}\mathbf{\times }\mathbf{100}\mathbf{\%} \\ \mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{ }\mathbf{=}\mathbf{22}\mathbf{.}\mathbf{57}\mathbf{\%} \end{gathered}$$

The mass percentage of NO released per mole of isoamyl nitrate ($\mathbf{\left(}{\mathbf{CH}}_{\mathbf{3}}\mathbf{\right)}{\mathbf{CHCH}}_{\mathbf{2}}{\mathbf{ONO}}_{\mathbf{2}}$ ) is  $\mathbf{22}\mathbf{.}\mathbf{57}\mathbf{\%}$