Question

7. (4 pts) Within each group, please rank the substances by their boiling points (indicate which is highest and lowest in your ranking): A)H–FOB® HP HD BFF Br-Br CHCIA

Answer 1

compounds A Here the given and are hydro. haloacids - HF , H-Bro, H-I, HI Now we know that with the incre- are in the molecular weight ie. the no. of elecfrons, the attrae- tive force i-e. the london dispersi on force increases leading to a higher boiling point So, the expected order of increa- sing boiling point would be a H-F KH-04H-Br <H-1 But, here is a discrepancy that HF has the highest & boiling point F has highest electronegativity and in H-F molecule due to a strong dipole moment, Hof molec. we can form intense intenmote- cular H-bonding leading to its highest boiling point

Ron H intermolecular H-bonding So, the connect order of increa- sing boiling point can be given as H-a LH-Bro LH-ITH-F H-F ) highest boiling point H-1 lowest boiling point. B) The given halogens are - F F Bro-Bro, al-Q, I-I As these are homonuclear diato- mie molecules, they all have zeno dipole moment and hence are non- polar.

0 n for non-polar molecule with the increase in the molecular weight that is london dispersion force also increases leading to highest boili ng point So the connect order of increasing boiling point can be given as - F-F Lal-ak Bro-Bn LI-I DY I-I F-F highest boiling point - lowest boiling point