Which statement is not correct about the trends in properties of the hydrogen halides from HCl to HI ?
A The boiling points decrease - AQA - A-Level Chemistry - Question 17 - 2019 - Paper 3
Question 17
Which statement is not correct about the trends in properties of the hydrogen halides from HCl to HI ?
A The boiling points decrease.
B The bond dissociation energy... show full transcript
Worked Solution & Example Answer:Which statement is not correct about the trends in properties of the hydrogen halides from HCl to HI ?
A The boiling points decrease - AQA - A-Level Chemistry - Question 17 - 2019 - Paper 3
Step 1
The boiling points decrease.
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Answer
This statement is not accurate as the boiling points of hydrogen halides actually increase from HCl to HI because of the increasing molecular size and van der Waals forces.
Step 2
The bond dissociation energy of H-X decreases.
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Answer
This statement is correct; the bond dissociation energy tends to decrease as the size of the halide increases, making H-I bond weaker than H-Cl.
Step 3
The polarity of the H-X bond decreases.
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Answer
This statement is also correct as the polarity decreases from HCl to HI due to the decreasing electronegativity difference between H and I compared to H and Cl.
Step 4
They are more easily oxidised in aqueous solutions.
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Answer
This statement is correct too, as larger halides can be more easily oxidised due to their higher dispersion forces leading to instability.
