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WorksheetsBond enthalpy
Total questions: 11
Worksheet time: 6mins
Use bond energies to determine the energy change for the following reaction and use the information to determine if it is an endothermic or exothermic reaction:
HCN + H2 --> CH3N2
Bond enthalpy is __________.
always negative
always positive
sometimes positive and sometimes negative
always zero
unpredictable
Is this equation endo- or exo-thermic?
2KNO3 (s) + energy --> 2KNO2 (s) + O2
endothermic
exothermic
Does breaking bonds require energy, release energy, or not involve energy at all?
requires energy to break
releases energy when broken
No energy involved
When new chemical bonds form, energy ____________.
is taken into the system.
is released from the system.
stays the same in the system.
Which process involves the absorption of energy?
Breaking of chemical bonds
Formation of chemical bonds
Both formation and breaking of bonds
What is the sign of enthalpy change (ΔH) for an exothermic reaction?
Positive
Negative
Zero
Which of the following best describes an endothermic reaction?
Energy is absorbed from the surroundings
No energy exchange occurs
Energy is released to the surroundings
In a reaction pathway diagram, what does the peak of the curve represent?
The energy of the products
The energy of the reactants
The activation energy or transition state
Which of the following statements is true about the activation energy shown in a reaction pathway diagram?
It is the difference in energy between reactants and products
It is the minimum energy required to start the reaction
It is always negative
How does the addition of a catalyst affect a reaction pathway diagram?
It lowers the activation energy
It raises the activation energy
It increases the energy of the products
