Chemistry - ALCOHOL & ETHER Question with Solution | TestHub

Question Explanation:

The question asks to calculate the stoichiometric quantity of electrons involved in the oxidation of a specific mass of ethanol to ethanoic acid.

Concept: Stoichiometry, Redox Reactions, Oxidation States

Solution:

Calculate Moles of Ethanol:

Molar Mass of Ethanol .${\mathrm{C}}_2{\mathrm{H}}_{5}OH=2\left(12\right)+6\left(1\right)+16=46g$/mol

$$Moles=\frac{Givenmass}{Molarmass}=\frac{46}{46}=1mole$$

Determine Electron Change:

We can determine the electrons involved by looking at the change in oxidation number of the carbon

atom undergoing oxidation.

In Ethanol ,${\mathrm{CH}}_3{\mathrm{CH}}_2\mathrm{OH}$ the functional group carbon has an oxidation state of –1.

In Ethanoic Acid ${\mathrm{CH}}_3\mathrm{CO}O\mathrm{H}$ , the carboxyl carbon has an oxidation state of +3.

Change in Oxidation State = -1 to +3 =4 . This means 4 electrons are lost per molecule.

Alternatively, using the balanced half-reaction: ${\mathrm{C}}_2{\mathrm{H}}_{5}OH+H_{2}O\to C{H}_{3}COOH+4H^{+}+4e^{-}$

Since 1 mole of ethanol releases 4 moles of electrons, and we have exactly 1 mole of reactant: Total

moles of electrons = 4.