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- Prepare a hot water bath by heating $100mL$ of hot tap water in a $250mL$ beaker to $80° C$. Turn the bunsen off.
- Into four, separate, labelled test tubes place $2mL$ of ethanol, butan-1-ol, butan-2-ol and 2-methylpropan-2-ol respectively.
- In another test tube mix $4mL$ of $0.1molL^{-1}$ $Na_{2}Cr_{2}O_{7}$ and $2mL$ of $6molL^{-1}$ $H_{2}SO_{4}$.
- Pour $1mL$ of the acidified $Na_{2}Cr_{2}O_{7}$ solution into each of the test tubes containing the alcohols and heat them in the hot water bath for about 5 minutes. If the aqueous and alcoholic phases do not mix, shake the mixture occasionally.
- Observe carefully for any evidence of reaction and note the relative rate of the reaction of each alcohol. Where a reaction has taken place carefully smell the contents of the tube. Write your observations in a suitable table.
- Into four separate test tubes place $2mL$ of ethanol, butan-1-ol, butan-2-ol and 2-methylpropan-2-ol respectively.
- In another test tube mix $2mL$ of $0.1molL^{-1}$ $KMnO_{4}$ and $1mL$ of $6molL^{-1}$ $H_{2}SO_{4}$.
- Add 3-5 drops of the acidified $KMnO_{4}$ to each of the test tubes containing the alcohols and shake gently.
- Observe carefully for any evidence of reaction and note the relative rate of the reaction of each alcohol. Where a re action has taken place, carefully smell the contents of the tube. Write your observations in a suitable table.
|
Ethanol |
Butan-1-ol |
Butan-2-ol |
2-methylpropan-2-ol |
| $Cr_{2}O_{7}^{2-}$ |
Colourless/very pale blue |
Blue |
Deeper blue |
NVR |
| $MnO_{4}^{-1}$ |
Colourless/very pale orange |
Orange |
Colourless (instant) |
Deeper orange |
$$\begin{align}
MnO_{4}^{-} \to ??? \to Mn^{2+} \\
\text{Purple} \to \text{Brown(incomplete)} \to \text{Pale pink/**Colourless**} \\
\\
Cr_{2}O_{7}^{2-}\to ??? \to Cr^{3+} \\
\text{Orange} \to \text{Blue (complex ion)} \to \text{Green}
\end{align}
$$
