Answer the following questions relating to the chemistry of the halogens. (a) The molecular formulas of diatomic bromine, chlorine, fluorine, and iodine are written below. Circle the formula of the molecule that has the longest bond length. Justify your choice in terms of atomic structure. Br2 Cl2 F2 I2 Br2Br2 and Cl2Cl2 can react to form the compound BrClBrCl. A chemistry teacher wants to prepare Br2Br2. The teacher has access to the following three reagents: NaBr(aq)NaBr(��), Cl2(g)Cl2(�), and I2(s)I2(�). Half-Reaction E°�° at 25°C(V)25°C(V) Br2+2e−→2Br−Br2+2�−→2Br− 1.071.07 Cl2+2e−→2Cl−Cl2+2�−→2Cl− 1.361.36 I2+2e−→2I−I2+2�−→2I− 0.530.53 (b) Using the data in the table above, write the balanced equation for the thermodynamically favorable reaction that will produce Br2Br2 when the teacher combines two of the reagents. Justify that the reaction is thermodynamically favorable by calculating the value of E°�° for the reaction. (c) The boiling point of Br2Br2 is 332K332K, whereas the boiling point of BrClBrCl is 278K278K. Explain this difference in boiling point in terms of all the intermolecular forces present between molecules of each substance.
Formal Charges
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Valence Bond Theory Vbt
Valence bond theory (VBT) in simple terms explains how individual atomic orbitals with an unpaired electron each, come close to each other and overlap to form a molecular orbital giving a covalent bond. It gives a quantum mechanical approach to the formation of covalent bonds with the help of wavefunctions using attractive and repulsive energies when two atoms are brought from infinity to their internuclear distance.
Answer the following questions relating to the chemistry of the halogens.
(a) The molecular formulas of diatomic bromine, chlorine, fluorine, and iodine are written below. Circle the formula of the molecule that has the longest bond length. Justify your choice in terms of atomic structure.
Br2 Cl2 F2 I2
Br2Br2 and Cl2Cl2 can react to form the compound BrClBrCl.
A chemistry teacher wants to prepare Br2Br2. The teacher has access to the following three reagents: NaBr(aq)NaBr(��), Cl2(g)Cl2(�), and I2(s)I2(�).
| Half-Reaction | E°�° at 25°C(V)25°C(V) |
| Br2+2e−→2Br−Br2+2�−→2Br− | 1.071.07 |
| Cl2+2e−→2Cl−Cl2+2�−→2Cl− | 1.361.36 |
| I2+2e−→2I−I2+2�−→2I− | 0.530.53 |
(b) Using the data in the table above, write the balanced equation for the
(c) The boiling point of Br2Br2 is 332K332K, whereas the boiling point of BrClBrCl is 278K278K. Explain this difference in boiling point in terms of all the intermolecular forces present between molecules of each substance.
The compound BrClBrCl can decompose into Br2Br2 and Cl2Cl2, as represented by the balanced chemical equation below.
2BrCl(g)⇄Br2(g)+Cl2(g)ΔH°=1.6kJ/molrxn2BrCl(�)⇄Br2(�)+Cl2(�)Δ�°=1.6kJ/mol���
A 0.1000.100 mole sample of pure BrCl(g)BrCl(�) is placed in a previously evacuated, rigid 2.00L2.00L container at 298K298K. Eventually the system reaches equilibrium according to the equation above.
(d) Calculate the pressure in the container before equilibrium is established.
(e) Write the expression for the equilibrium constant, Keq���, for the decomposition of BrClBrCl.
(f) Determine the value of Keq��� for the decomposition reaction of BrClBrCl at 298K298K.
(g) Calculate the bond energy of the Br−ClBr−Cl bond, in kJ/molkJ/mol, using ΔH°Δ�° for the reaction (1.6kJ/molrxn)(1.6kJ/mol���) and the information in the following table.
| Bond | Bond Energy (kJ/mol)(kJ/mol) |
| Br−BrBr−Br | 193193 |
| Cl−ClCl−Cl | 243243 |
| Br−ClBr−Cl | ? |
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