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Draw a diagram to show the strongest type of interaction between two molecules of ethanol (C2H5OH) in the liquid phase - AQA - A-Level Chemistry - Question 8 - 2019 - Paper 1
Question 8
Draw a diagram to show the strongest type of interaction between two molecules of ethanol (C2H5OH) in the liquid phase. Include all lone pairs and partial charges i... show full transcript
Worked Solution & Example Answer:Draw a diagram to show the strongest type of interaction between two molecules of ethanol (C2H5OH) in the liquid phase - AQA - A-Level Chemistry - Question 8 - 2019 - Paper 1
Step 1
Draw a diagram to show the strongest type of interaction between two molecules of ethanol.
Answer
The strongest type of interaction between ethanol molecules is hydrogen bonding.
In the diagram, illustrate two ethanol molecules. Each ethanol molecule should have a hydroxyl (-OH) group, with lone pairs represented on the oxygen atom. Draw an arrow indicating the hydrogen bond between the hydrogen atom of one ethanol molecule and the oxygen atom of another ethanol molecule. The partial charges should be indicated by δ+ on the hydrogen and δ- on the oxygen.
Step 2
In terms of the intermolecular forces involved, explain the difference in boiling points.
Answer
Ethanol has a boiling point of 78 °C, while methoxymethane has a boiling point of -24 °C.
The primary reason for this difference lies in the presence of hydrogen bonds in ethanol, which are the strongest type of intermolecular forces. These hydrogen bonds require considerable energy to break, leading to a higher boiling point for ethanol. In contrast, methoxymethane has weaker intermolecular forces, primarily Van der Waals forces, resulting in a significantly lower boiling point. Therefore, the presence of hydrogen bonding in ethanol explains its higher boiling point compared to methoxymethane.
Step 3
Draw the shape of the POCl3 molecule and the shape of the ClF4- ion.
Answer
For POCl3, the shape is distorted tetrahedral due to one double bond and one lone pair on the phosphorus atom.
For ClF4-, the shape is square planar, with four fluorine atoms around the chlorine atom and two lone pairs.
The bond angle in ClF4- is 90°.