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Question

Is there any way of determining this answer? (like a trend on the table or just how would you do it?

If KBr, C2H5OH, C2H6, and He are arranged in order of increasing boiling point, the list is
a. He < C2H5OH < C2H6 < KBr
b. KBr < C2H6 < C2H5OH < He
c. He < C2H6 < C2H5OH < KBr
d. KBr < C2H6 < He < C2H5OH
e. C2H5OH < C2H6 < He < KBr

Answer 1

c

Answer 2

Actually DavidK93 in this case it is very straightforward to find the order.As you very correctly pointed out the boiling point depends on the strength of the intermolecular forces. The stronger these forces are the more energy you need to break them and thus the higher the boiling point will be.

Ionic interactions are the strongest, so KBr which is a crystalline solid at room temperature will have the highest boiling point of all.

Non-polar molecules like He and C2H6 interact only through dispersion forces which are the weakest type of intermolecular forces.C2H5OH has a similar size to C2H6 so the dispersion forces are approximately the same. However,C2H5OH will form, in addition to dispersion forces, hydrogen bonds which are stronger than dispersion forces.Thus it will have higher boiling point than C2H6.

Dispersion forces increase as the surface of the molecules increase, thus the C2H6 molecule which is bigger than He will have stronger intermolecular forces and thus higher boiling point.

Therefore the correct answer is C
He

Answer 3

He < C2H6 < C2H5OH < KBr
boiling points are actually indicators of strength of forces in molecules,atoms & compounds(whatever the case you are dealing with). KBr is ionic compound & so a large amount of energy is required to boil it.so it has highest melting point.C2H5OH has hydrogen bonding.that,s why its boiling point is also higher but less than KBr .C2H6 has only london dispersion forces because it is non polar compound.these forces are weakest of all electrical forces.so C2H6 has low b.p. He has lowest b.p.the reason is that london dispersion forces are there in it. but very little

Answer 4

You need to look up the boiling points of each of these substances. In general, boiling point depends on the strength of intermolecular forces. Molecules that are more strongly attracted to each other will need a greater input of energy to resist that attraction, which is required for the molecules to separate from each other into a gas. Molecules tend to be more attracted to each other if they are highly polar (due to dipole forces) or if they are composed of large atoms (due to the Van der Waals force). However, these trends are not strong enough or sufficiently well-defined for you determine this order from the list alone. Look up each substance and record its boiling point, and then order them on that basis.

Answer 5

Open wikipedia or google, look for each element, write down their boiling points, and pick the right answer.