Alcohol levels in blood can be determined by a redox...

Alcohol levels in blood can be determined by a redox reaction with potassium dichromate according to the balanced equation $\begin{array}{rl}{\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}(a q)+2 \mathrm{Cr}_{2} \mathrm{O}_{7}^{2-}(a q)+16 \mathrm{H}^{+}(a q)} \longrightarrow \\ {2} & {\mathrm{CO}_{2}(g)+4 \mathrm{Cr}^{3+}(a q)+11 \mathrm{H}_{2} \mathrm{O}(l)}\end{array}$ What is the blood alcohol level in mass percent if 8.76 $\mathrm{mL}$ of 0.04988 $\mathrm{M} \mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}$ is required for complete reaction with a 10.002 $\mathrm{g}$ sample of blood?

Alcohol levels in blood can be determined by a redox reaction with potassium dichromate according to the balanced equation
$\begin{array}{rl}{\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}(a q)+2 \mathrm{Cr}_{2} \mathrm{O}_{7}^{2-}(a q)+16 \mathrm{H}^{+}(a q)} \longrightarrow \\ {2} & {\mathrm{CO}_{2}(g)+4 \mathrm{Cr}^{3+}(a q)+11 \mathrm{H}_{2} \mathrm{O}(l)}\end{array}$
What is the blood alcohol level in mass percent if 8.76 $\mathrm{mL}$ of 0.04988 $\mathrm{M} \mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}$ is required for complete reaction with a 10.002 $\mathrm{g}$ sample of blood?

Key Concepts

Stoichiometry

Stoichiometry involves using the balanced chemical equation to relate the quantities (in moles) of reactants and products. This concept is essential for determining how much of one substance reacts with or is produced by a given amount of another substance based on their mole ratios.

Molarity

Molarity is a measure of concentration expressed as the number of moles of solute per liter of solution. It allows for the conversion of solution volume to moles of a reactant, which is critical in quantitative analyses such as titrations.

Redox Reactions

Redox reactions, or oxidation-reduction reactions, involve the transfer of electrons between species. They are particularly important in titrations where the electron transfer can be used to quantify the amount of a substance present, as indicated by changes in the oxidation states.

Titration and Volumetric Analysis

Titration is a lab technique in which a solution of known concentration is gradually added to a solution containing the analyte until the reaction reaches completion. Volumetric analysis uses these precise volume measurements to calculate the concentrations of substances in a sample.

Mass Percent Calculation

Mass percent is a way to express the concentration of a component in a mixture, calculated as the mass of the component divided by the total mass of the mixture, multiplied by 100. This metric is useful for evaluating the proportion of a substance in complex samples.

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