Bond Energies Flashcards
Energy Changes (19 cards)
What must always be supplied to break bonds?
Energy
Bond breaking is an endothermic process.
What type of process is bond breaking?
Endothermic
Energy must be supplied to break existing bonds.
What type of process is bond formation?
Exothermic
Energy is released when new bonds are formed.
In exothermic reactions, what is true about the energy released by forming bonds?
It is greater than the energy used to break them.
In endothermic reactions, what is true about the energy used to break bonds?
It is greater than the energy released by forming them.
What is bond energy?
The energy associated with a particular chemical bond.
How does bond energy vary?
It varies slightly depending on the compound the bond occurs in.
What is the formula to calculate the overall energy change for a reaction?
Energy required to break bonds - Energy released by forming bonds.
Fill in the blank: Bond breaking is an _______ process.
endothermic
Fill in the blank: Bond forming is an _______ process.
exothermic
What is the overall energy change for the reaction if the energy required to break bonds is 678 kJ/mol and the energy released by forming bonds is 862 kJ/mol?
-184 kJ/mol
What bond energy is associated with H-H?
+436 kJ/mol
What bond energy is associated with Cl-Cl?
+242 kJ/mol
What bond energy is associated with H-Cl?
+431 kJ/mol
True or False: The bond energies of Br-Br are weaker than Cl-Cl bonds.
True
True or False: Less energy is needed to break the bonds in the reaction with bromine than with chlorine.
True
Why can’t you compare the overall energy changes of reactions without bond energy data?
You need to know the numerical differences in the bond energies.
What is the first step in calculating energy change for a reaction?
Find the energy required to break the original bonds.
What is the second step in calculating energy change for a reaction?
Find the energy released by forming the new bonds.
