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Topic 4: Chemical bonding

4. Bonding and energy: Relating bond formation and bond breaking equations to energy:

1. Which statement is true concerning the reaction

N(g) + N(g) ----- N2(g)

1) A bond is broken and energy is absorbed 3) A bond is formed and energy is absorbed
2) A bond is broken and energy is released 4) A bond is formed and energy is released

2. Given the balanced equation:
I2 ------------ I + I

Which statement describes the process represented by this equation?

1) A bond is formed, and energy will be absorb 3) A bond is broken, and energy will be absorb
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2) A bond is formed, and energy will be release 4) A bond is broken, and energy will be release

3. Given the equation

H + H -------- H2
Which statement best describes this process?

1) It is exothermic, and a bond is formed 3) It is endothermic, and a bond is formed
2) It is exothermic, and a bond is broken 4) It is endothermic, and a bond is broken

4. Which statement is true concerning the process taking place in the reaction

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AB + energy --------- A + B
1) A bond is broken and energy is absorbed 3) A bond is formed and energy is absorbed
2) A bond is broken and energy is released 4) A bond is formed and energy is released
5. Given the balanced equation representing a reaction

Cl2 (g) + energy ---------- Cl(g) + Cl(g)
What occurs during this change?
1) Energy is released and a bond is formed 3) Energy is absorbed and a bond is formed
2) Energy is released and a bond is broken 4) Energy is absorbed and a bond is broken

6. In the balanced equation
HCl ------------------ H2 + Cl2
Which is correct of the process talking place as bonds are broken and formed?
1) The breaking of H–Cl bond is exothermic 3) The forming of H–H bond is exothermic
4) The forming of Cl–Cl bond is endothermic
2) The breaking of H–Cl bond is exothermic

7. Given the reaction:
H2 + Cl2 --------------- 2 HCl
Which statement best describes the energy changes as bonds are formed and broken in this reaction?

1) The breaking of Cl–Cl bond absorbs energy 3) The forming of H–Cl bond absorbs energy
2) The breaking of H–H bond releases energy 4) The forming of H–Cl bond absorbs energy

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