arrange the following from highest boiling point to lowest boiling point?

Question

bromine gas, a non-polar molecule
chlorine gas, a non-polar molecule
potassium bromide, a polar molecule

would the order be KBr, Cl2, Br2?

bromine gas=159.8g
chlorine gas=70g
potassium bromide=119g

Answer 1

KBr > Br2 > Cl2

The boiling point depends on the strength of the intermolecular forces. The stronger these are the higher the boiling point (since it will require more energy to break them and enter the gaseous phase)

KBr is actually an ionic compound, a salt. The forces between the K+ and Br- ions are so strong that it is a crystallic solid. So of course it has the highest boiling point

Cl2 and Br2 are non-polar molecules. Thus the only forces present are dispersion forces (which are the weakest type of intermolecular forces). These are proportional to the size of the molecule and the surface available for interaction.
Br2 is bigger than Cl2, therefore it will exhibit stronger dispersion forces and it will have a higher boiling point.

Answer 2

Since Cl2 is smaller than Br2, Cl2 will have a lower boiling point. KBr will have by far the highest boiling point.

At room temperature, Cl2 is a gas, Br2 is a liquid, and KBr is a solid

Answer 3

C8H18>C6H14>C4H10>C3H8. All these compounds are alkanes, saturated hydrocarbons with the general formula CnH2n+2. The boiling point depends on the intramolecular forces of attraction (van der Waals) which here depend on the molecular mass so the hydrocarbons are listed in order of decreasing molecular weights.

Answer 4

I didn't know gases had boiling points !