Respuesta :
Answer: The mass percent of alcohol in blood is 0.183 %
Explanation:
To calculate the moles for given molarity, we use the equation:
[tex]\text{Molarity of the solution}=\frac{\text{Moles of solute}}{\text{Volume of solution (in L)}}[/tex]
Molarity of [tex]Cr_2O_7^{2-}[/tex] solution = 0.05961 M
Volume of solution = 35.46 mL = 0.03546 L (Conversion factor: 1 L = 1000 mL)
Putting values in above equation, we get:
[tex]0.05961M=\frac{\text{Moles of }Cr_2O_7^{2-}}{0.03546L}\\\\\text{Moles of }Cr_2O_7^{2-}=(0.05961mol/L\times 0.03546L)=2.11\times 10^{-3}mol[/tex]
The given chemical reaction follows:
[tex]16H^+(aq.)+2Cr_2O_7^{2-}(aq.)+C_2H_5OH(aq.)\rightarrow 4Cr^{3+}(aq.)+2CO_2(g)+11H_2O(l)[/tex]
By Stoichiometry of the reaction:
2 moles of dichromate ions react with 1 mole of ethanol.
So, [tex]2.11\times 10^{-3}mol[/tex] of dichromate ions will react with = [tex]\frac{1}{2}\times 2.11\times 10^{-3}=1.06\times 10^{-3}mol[/tex]
- To calculate the number of moles, we use the equation:
[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex]
Moles of ethanol = [tex]1.06\times 10^{-3}mol[/tex]
Molar mass of ethanol = 46.07 g/mol
Putting values in above equation, we get:
[tex]1.06\times 10^{-3}mol=\frac{\text{Mass of ethanol}}{46.07g/mol}\\\\\text{Mass of ethanol}=(1.06\times 10^{-3}mol\times 46.07g/mol)=0.0488g[/tex]
- To calculate the mass percent of ethanol in blood, we use the equation:
[tex]\text{Mass percent of ethanol}=\frac{\text{Mass of ethanol}}{\text{Mass of blood plasma}}\times 100[/tex]
Mass of blood plasma = 26.60 g
Mass of ethanol = 0.0488 g
Putting values in above equation, we get:
[tex]\text{Mass percent of ethanol}=\frac{0.0488g}{26.60g}\times 100=0.183\%[/tex]
Hence, the mass percent of alcohol in blood is 0.183 %
