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
A The boiling points decrease.
96%
114 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
This statement is correct as the boiling points of hydrogen halides generally increase from HCl to HI due to increasing molecular weight and Van der Waals forces.
Step 2
B The bond dissociation energy of H–X decreases.
99%
104 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
This statement is also correct. The bond dissociation energy does decrease as we move from HCl to HI because the bond becomes weaker due to the increasing size of the halide ion.
Step 3
C The polarity of the H–X bond decreases.
96%
101 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
This statement is misleading. The polarity of the H–X bond actually decreases from HCl to HI due to the decreasing electronegativity difference as we move down the group.
Step 4
D They are more easily oxidised in aqueous solutions.
98%
120 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
This statement is correct. As we go from HCl to HI, the hydrogen halides become more reducing and thus are more easily oxidised in aqueous solutions.
