Chemical reactions and energy Flashcards
What are reactions that release energy called?
Exothermic reactions.
What are reactions that take in energy overall called?
Endothermic reactions.
Explain exothermic reactions in a energy profile.
The energy of the products is less than the energy of the reactants because energy in the form of heat has been given out to its surroundings.
Explain endothermic reactions in a energy profile/
The energy of the products is greater than that of the reactants because energy has been taken in from the surroundings.
What is activation energy?
The minimum amount of energy that is required to activate atoms or molecules to a condition in which they can undergo chemical transformation or physical transport. Can be seen in an energy profile as the little rise before the fall.
What factors are needed for a ‘successful’ atom collsion?
- Collide with another kinetic energy to kick start the reaction
- Collide in the correct orientation
What is combustion?
A fuel burning in oxygen.
What is the breaking of a bond?
Endothermic, it requires energy to be put in.
What is the formation of a bond?
Exothermic, it gives out energy.
Why does ‘bond energy’ always stay the same?
Breaking and forming bonds always involves the same value for energy change except that when bonds are broken, the energy is used and when bonds are formed, the energy is released.
What does a positive and negative end of reaction energy value mean?
Positive = endothermic Negative = exothermic
