Bond Energy and Reaction Energy Worksheet

Question 1

Which process requires an energy input in this model?

1. Breaking a covalent bond
2. Forming the same covalent bond
3. Moving an unchanged formula to a new line
4. Counting the atoms in a formula

Question 2

A model reaction requires 450 kJ to break bonds and releases 600 kJ when bonds form. Calculate its net energy change.

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Question 3

A reaction forms two bonds of the same kind. Forming one releases 200 kJ on the scale used. How much energy is released when both form?

1. 100 kJ
2. 200 kJ
3. 400 kJ
4. 600 kJ

Question 4

Explain how the energy absorbed to break a particular bond compares with the energy released by forming the same bond in the model.

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Question 5

Which bonds are broken for one mole of reaction as written?

1. One mole each of H–H and Cl–Cl
2. Two moles of H–Cl
3. One mole of H–Cl only
4. Two moles each of H–H and Cl–Cl

Question 6

Use the table to estimate the net energy change for one mole of reaction as written. Show the separate breaking and forming amounts.

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Question 7

Which statement describes the bond-energy estimate?

1. Bond breaking absorbs more than bond formation releases.
2. Bond formation releases more than bond breaking absorbs.
3. Both amounts are equal.
4. Bond formation absorbs both amounts.

Question 8

A student adds 679 kJ and 862 kJ to calculate the net energy change. Explain why the two amounts need different signs.

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