Chapter U2, Problem C8.4RE

(a)

Interpretation Introduction

Interpretation: Comprehend the Lewis dot structure of $\text{HBr}$ and label dipole in the molecule.

Concept Introduction: The chemical compounds can be classified as covalent compound and ionic compound. Ionic compounds have complete negative and positive charges on it whereas covalent compounds are formed by equal sharing of electrons between bonded atoms.

The polarity of molecule depends on the presence of electropositive and electronegative atoms present in the molecule.

Due to electronegativity difference between bonded atoms, partial charges induce on the bonded atoms. The partial charges effect the physical properties of the polar molecules.

Answer to Problem C8.4RE

  

Explanation of Solution

In the Lewis structure of $\text{HBr}$ molecule, Br has 7 valence electrons and H has 1 electron.

Thus, total valence electrons in $\text{HBr}$ molecule = 1 +7 = 8 valence electrons

In $\text{HBr}$ molecule, Br is more electronegative element than H atom. This is because Br is a non-metal with 7 valence electrons. Therefore Br tends to accept electrons to get octet configuration. That makes it more electronegative than H atom. Due to this difference in electronegativity of bonded atoms, Br gets partial negative charge and H gets partial positive charge.

  

(b)

Interpretation Introduction

Interpretation: Comprehend the attraction of $\text{HBr}$ towards charged wand and formation of round drop on waxed paper.

Concept Introduction: The chemical compounds can be classified as covalent compound and ionic compound. Ionic compounds have complete negative and positive charges on it whereas covalent compounds are formed by equal sharing of electrons between bonded atoms.

The polarity of molecule depends on the presence of electropositive and electronegative atoms present in the molecule.

Due to electronegativity difference between bonded atoms, partial charges induce on the bonded atoms. The partial charges effect the physical properties of the polar molecules.

Explanation of Solution

In $\text{HBr}$ molecule, Br is more electronegative element than H atom. This is because Br is a non-metal with 7 valence electrons. Due to this difference in electronegativity of bonded atoms, Br gets partial negative charge and H gets partial positive charge.

  

Because of the presence of partial charges on $\text{HBr}$ molecule, it will attract towards charged wand.

Since it is a polar molecule therefore it will be soluble in polar solvents like water. Whereas it will be insoluble in non-polar solvents therefore it will make round drop on waxed paper as wax is a non-polar molecule.

(c)

Interpretation Introduction

Interpretation: Comprehend the type of bond exists between H and Br in $\text{HBr}$ molecule.

Concept Introduction: The chemical compounds can be classified as covalent compound and ionic compound. Ionic compounds have complete negative and positive charges on it whereas covalent compounds are formed by equal sharing of electrons between bonded atoms.

The polarity of molecule depends on the presence of electropositive and electronegative atoms present in the molecule.

Due to electronegativity difference between bonded atoms, partial charges induce on the bonded atoms. The partial charges effect the physical properties of the polar molecules.

Answer to Problem C8.4RE

  $\text{HBr}$ molecule has polar covalent bond.

Explanation of Solution

In the Lewis structure of $\text{HBr}$ molecule, Br has 7 valence electrons and H has 1 electron.

Thus, total valence electrons in $\text{HBr}$ molecule = 1 +7 = 8 valence electrons

To get the octet configuration, Br share one of its valence electron with H to form covalent bond and H also shares its electron to get duplet configuration that leads to formation of polar covalent bond in molecule.

  

Since it is a polar molecule therefore it will be soluble in polar solvents like water. Whereas it will be insoluble in non-polar solvents therefore it will make round drop on waxed paper as wax is a non-polar molecule.

(d)

Interpretation Introduction

Interpretation: Comprehend the smell of $\text{HBr}$ molecule.

Concept Introduction: The chemical compounds can be classified as covalent compound and ionic compound. Ionic compounds have complete negative and positive charges on it whereas covalent compounds are formed by equal sharing of electrons between bonded atoms.

The polarity of molecule depends on the presence of electropositive and electronegative atoms present in the molecule.

Due to electronegativity difference between bonded atoms, partial charges induce on the bonded atoms. The partial charges effect the physical properties of the polar molecules.

Answer to Problem C8.4RE

  $\text{HBr}$ molecules have pungent smell.

Explanation of Solution

In $\text{HBr}$ molecule, Br is more electronegative element than H atom. This is because Br is a non-metal with 7 valence electrons. Due to this difference in electronegativity of bonded atoms, Br gets partial negative charge and H gets partial positive charge.

  

Because of the presence of partial charges on $\text{HBr}$ molecule, it is a polar molecule and soluble in water. A polar molecule can easily stick with receptor site in the nose and also soluble in mucous membrane of the nose therefore they have pungent smell.