Worksheet: Molar Energy Units

In this worksheet, we will practice using Avogadro's number to convert between molar energies and the energies of single bonds.

Q1:

The molar bond energy of F 2 is 159 kJ/mol. Calculate the energy of one F F bond.

  • A 3 . 7 9 × 1 0 1 9 J
  • B 9 . 5 8 × 1 0 1 9 J
  • C 1 . 6 5 × 1 0 1 9 J
  • D 2 . 6 4 × 1 0 1 9 J
  • E 2 . 5 5 × 1 0 1 9 J

Q2:

What is Avogadro’s number to 3 significant figures?

  • A 1 . 3 8 × 1 0 2 3
  • B 3.14
  • C 1 0 . 0 9
  • D 6 . 0 2 × 1 0 2 3
  • E 6 . 7 1 × 1 0 1 4

Q3:

3.70 mol of C l C l bonds release 888 kJ of energy when they form. How much energy is released when 1 0 0 0 C l C l bonds form?

  • A 4 . 0 1 × 1 0 J
  • B 3 . 9 9 × 1 0 J
  • C 1 . 4 8 × 1 0 J
  • D 3 . 9 9 × 1 0 J
  • E 1 . 4 8 × 1 0 J

Q4:

Which of the following quantities of bonds requires the most energy to break?

  • A 1 . 0 m o l C C ( 8 3 5 k J / m o l )
  • B 2 . 0 m o l H C l ( 4 2 8 k J / m o l )
  • C 1 . 7 m o l O O ( 4 9 4 k J / m o l )
  • D 2 . 0 m o l H H ( 4 3 6 k J / m o l )
  • E 5 . 8 m o l I I ( 1 4 8 k J / m o l )

Q5:

Every molecule of iodine, I 2 , has an iodine–iodine bond, I I . The energy required to break one of these bonds is 2 . 5 1 × 1 0 1 9 J. How much energy is required to break 1.00 mole of these I I bonds?

  • A 2 . 5 1 × 1 0 1 9 J
  • B 4 . 1 7 × 1 0 4 3 J
  • C 3 . 4 4 × 1 0 1 2 J
  • D 1 . 5 1 × 1 0 5 J
  • E 9 . 0 1 × 1 0 1 0 J

Q6:

The energy of the hydrogen–hydrogen bond in H 2 is 436 kJ/mol. Which of the following is an equivalent description of the bond energy in hydrogen?

  • AFor every hydrogen–hydrogen bond in a hydrogen molecule formed, 436 kJ of energy is released.
  • B 436 kJ of energy is released when the hydrogen–hydrogen bonds of 6 . 0 2 × 1 0 hydrogen molecules are broken.
  • CFor every hydrogen–hydrogen bond in a hydrogen molecule broken, 436 kJ of energy is released.
  • D 436 kJ of energy is required to break the hydrogen–hydrogen bonds of 6 . 0 2 × 1 0 hydrogen molecules.
  • E 436 kJ of energy is required to form the hydrogen–hydrogen bonds of 6 . 0 2 × 1 0 hydrogen molecules.

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