Question

The hydrides of group 5A are NH3, PH3, AsH3, and SbH3. Arrange them from highest to lowest boiling point.

Answer 1

Explanation:

The hydrides of group 5A show an increase in boiling point from $PH_{3}$ to $BiH_{3}$. But boiling point of $NH_{3}$ is higher than rest of the hydrides of group 5A.

This is because electronegativity of nitrogen is higher than hydrogen. So, it will attract electrons of hydrogen more towards itself. Thus, polarity will develop between nitrogen and hydrogen bond. As a result, $NH_{3}$ will undergo strong hydrogen bonding.

In order to break this N-H bond, high temperature is required. Thus, boiling point of $NH_{3}$ will be high.

On the other hand, on moving down the group there will be an increase in mass. Thus, there will be increase in Vander waals forces of attraction and as a result, there will be increase in boiling point from  $PH_{3}$ to $BiH_{3}$.

Whereas the boiling point of $NH_{3}$  is higher than those of $PH_{3}$ and $AsH_{3}$ but lower than $SbH_{3}$ and $BiH_{3}$ because higher Vander waals forces of attraction more than compensates the increase in boiling point of $NH_{3}$ because of hydrogen bonding.

Thus, the order from highest to lowest boiling point for hydrides of group 5A are as follows.

     $BiH_{3}$ > $SbH_{3}$ > $NH_{3}$ > $AsH_{3}$ > $PH_{3}$    

Answer 2

Answer:

The arrangement of the hydrides of group 5A from the highest to lowest boiling point is as follows:

SbH₃ > NH₃> AsH₃ > PH₃

Explanation:

The concept used in the question is molecular weight and intermolecular forces. The first step is to check intermolecular forces in the given hydrides. After that, the molecular weight is taken into account for ranking the molecules.  

Further Explanation:

The covalent bond is present in all the hydrides of Group 5A. Intermolecular forces and molecular weight affect the boiling point of these hydrides. Hydrogen bonding is formed because of high electro-negativity difference in the molecules and it is proportional to polarity.

Compounds with higher intermolecular force have higher boiling points. This is because, during the phase transition, they require more energy to able to break the bonds. Among the hydrides, NH₃ has hydrogen bond while SbH₃, AsH₃ and PH₃ are shown London-dispersion forces and dipole-dipole interactions.  

Compared to PH₃ and AsH₃, SbH₃ has the highest boiling point due to its high molecular weight.  After that, the boiling point of AsH₃ is higher than PH₃.  

Compared to dipole-dipole and London-dispersion forces, the Hydrogen-bonding is strong. Therefore, the boiling point of NH₃ would be higher than the other three elements. But the molar mass of SbH₃ is greater than as compared to NH₃ and SbH₃ would have a higher London-dispersion force. Therefore, the boiling point of NH₃ is less as compared to SbH₃.

Hence, the arrangement of the hydrides of group 5A from the highest to lowest boiling point is as follows:

SbH₃ > NH₃> AsH₃ > PH₃

Learn More:  

boiling point of hydrides: brainly.com/question/11586812 ; Answered by: AsiaWoerner

Learn more :

about relationship between boiling point and intermolecular forces: brainly.com/question/3472771; Answered by: guesst555

Keyword:

Arrangement of the Hydrides of Group 5A, Electro-Negativity difference in the Molecules, NH₃ Molecule has more Electronegative Nitrogen and Hydrogen.