Rank the following molecules from lowest to highest boiling point H2 Br2 and F2

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1) H2 < F2 < Br2

Bigger molecules will have stronger London dispersion forces. So Br2 has the strongest forces, and H2 will have the weakest. Correspondingly, Br2 will have the highest boiling point and H2 will have the lowest boiling point.

2) HBr < HF

HBr and HF are hydrogen halides. F, Cl, Br, and I belong to the group of halogens.

Talking about the boiling point, it depends upon the hydrogen bonding present between the molecules.

Now, if we consider the above molecules, i.e. HI, HBr, and HCl. In these molecules, the dominating interactions would be van der Waals forces. As among these three halides, HI has the larger size or molecular mass.

Then we know, larger the size, or molecular mass of hydrogen halides, greater will be the van der Waals forces, higher the boiling point. The presence of Hydrogen bonding is negligible in these halides.

If we talk about the HF, it has strong hydrogen bonding, thus has the highest boiling point.

Therefore, HF exists in the liquid state, and HI, HBr, and HCl exists in the gaseous state.

We can conclude, the order of boiling point followed is HF > HI > HBr > HCl.

Don’t get confused between the boiling points of HF, and HI. The confusion can occur why HF has a higher boiling point than the HI. The reason is the presence of strong hydrogen bonding in the HF, as hydrogen intermolecular interactions are greater than the van der Waals forces. So, HF has a higher boiling point than the HI.

3) Of the three compounds, HBr should have the lowest boiling point because it has

the weakest IMFs (HBr is dipole-dipole, HF and H2O are hydrogen bonds). Between

water and HF, I would expect HF to have a lower boiling point because it has less

mass than water and should be easier to boil. Water also has two opportunities to

hydrogen bond with the oxygen, so it will be more difficult to separate the molecules into the gas phase. So HBr < HF < H2O

4) H2O: 100°C

Br2: 59°C

F2: -188°C

H2: -253°C

HBr: -66°C

HF: 19.5°C

Br2 and F2 are nonpolar, so they have low boiling points, and F2 should be lower than Br2 because of its smaller size/mass (it is less polarizable). Br2 has a higher boiling

point than HF because of its large mass and size, which makes it more polarizable. H2O has the highest boiling point because it has the strongest/most IMFs. HF has a

higher boiling point than HBr because of hydrogen bonds.

Activity: Intermolecular Forces1)IF you used HF and HF in this same simulation, predict the observations in the DataTable belowRelative force to pullapartPolar ornonpolar?IMFBr2and Br2easyNon polarLondon DispersionH2and H2easyNon polarLondon DispersionHBr and HBrdifficultpolarDipole-DipoleH2and HBrmediumpolar-nonpolarInduced DipolePREDICT:HF andHFdifficultpolarDipole DipoleAnalysisConsidering the observed IMF and strength of those forces, complete the following questionswith your best predictions.1)Rank the following molecules from lowest to highest boiling point:H2, Br2, and F2Explain your prediction based on IMF..2)Predict which of the following has the highest boiling point:HF or HBr.Explain your