Question

Of the following, ________ should have the highest critical temperature. Of the following, ________ should have the highest critical temperature. CH4 H2 CCl4 CBr4 CF4

Answer 1

CBr4

Step-by-step explanation:

Critical temperature is dependent on the strength of the intermolecular forces.

First consider the types of intermolecular forces and the order of their strengths.

Dispersion forces < dipole-dipole forces < hydrogen bonding < ionic bonding

Remember, dispersion forces are present in all cases

H2: only dispersion forces are present

CH4, CCl4, CBr4, CF4: only dispersion forces are present

In order to break the tie we must start considering molar mass because larger molar masses correspond to larger intermolecular forces. Calculating molar mass shows that CBr4 is the largest and will have the strongest intermolecular forces and therefore will have the highest critical temperature.

The answer is CBr4

Answer 2

H2

Step-by-step explanation:

Critical temperature is the temperature above which gas cannot be liquefied, regardless of the pressure applied.

Critical temperature directly depends on the force of attraction between atoms, it means stronger the force of higher will be the critical temperature. So, from the given options H2 should have the highest critical temperature because of high attractive forces due to H bonding.

Hence, the correct option is H2.