Bond Energy and Heat of Reaction Notes Flashcards
(16 cards)
What is the formula for Heat of Reaction?
△H
Heat of Reaction represents the energy change during a chemical reaction.
What type of reaction has a negative △H?
Exothermic Reactions
In exothermic reactions, reactants lose energy to the environment.
What type of reaction has a positive △H?
Endothermic Reactions
In endothermic reactions, reactants gain energy from the environment.
What is potential energy in the context of chemical bonds?
Stored energy that can be converted into another type of energy
An example is lifting an object, which adds potential energy.
What is bond energy?
The energy stored in the chemical bonds
Bond energy is a measure of the stability of a bond.
What factors affect bond energy?
- Type of bond
- Which elements are bonded together
Bond energy varies with single, double, and triple bonds.
What happens to atoms in a chemical reaction?
Atoms in the reactants must be separated and then recombined to form the products
This involves breaking and forming bonds.
What is required to break bonds?
Energy
Energy must be supplied to separate bonded atoms.
What happens when bonds are made?
Energy is released
This energy release contributes to the overall energy change in a reaction.
How is energy conserved in chemical reactions?
The amount of energy released when making a bond is the same as the energy required to break the same bond
This principle underlies the balance of energy in reactions.
What is the equation for the combustion of methane?
CH4 + 2 O2 → CO2 + 2 H2O
This reaction illustrates the breaking and forming of bonds.
What does an energy exchange diagram show?
A comparison of energy needed to break reactants and energy released through products
Arrows indicate energy input and release.
What do arrows pointing up represent in energy diagrams?
Energy input
This indicates the energy required to break bonds.
What do arrows pointing down represent in energy diagrams?
Energy released
This indicates the energy released when new bonds are formed.
What indicates an exothermic reaction in energy diagrams?
Energy released is more than the energy input
This results in a net release of energy.
What indicates an endothermic reaction in energy diagrams?
Energy released is less than the energy input
This results in a net absorption of energy.
