GS-2 Physical Sciences Question 12

[hey.aman8005]

Hi I was wondering if anyone else found the reasoning of question 12 faulty.

The question is
12.The passage states that HCl is expected to have a higher boiling point than either H2 or Cl2. The likely reason is that HCl:
1. exhibits weak dipole-dipole interactions, unlike H2 and Cl2 [x]
2. has a greater molecular mass than either H2 or Cl2 [x]
3. is less polar than either H2 or Cl2 [x]
4. is a smaller molecule than H2 and Cl2

and then the answer says A ... it says that HCl has weaker dipole dipole interactions.. isnt the OPPOSITE OF THIS TRUE????

thanks

[admin]

In the world of chemical bonds, dipole-dipole interactions are relatively week. However, these weak bonds which exist between HCl molecules is greater than having no intermolecular bonds at all (ie H2, Cl2) thus answer choice A is correct.

[abby_aprak4603]

Yeah..I thought it seemed a bit faulty too but I guess not. I'm still finding it hard to understand. It seems to undermine everything I thought was true in chemical bonding. hmm..

[abby_aprak4603]

Oh..I get it now. "weak" is only used in a relative sense.

[mcat_premed3832]

exactly!

[ebete8574]

What threw me off was the comparison to H2 and Cl2. I get that HCl has relatively weak dipole interactions, but stronger than H2 and Cl2 (since these don't exhibit dipole inter.) right?

tricky!