Reaction and energy Flashcards
(21 cards)
What is a chemical reaction?
Process that leads to chemical transformation of one set of chemical substances to another.
How are chemical reactions formed
Chemical reactions are formed when particles collide and are rearranged to form new particles.
Chemical energy
Energy stored in bonds between atoms in a substance.
Where can chemical energy result from?
- Attraction between electrons and protons in atoms.
- Repulsion between nuclei
- Repulsion between electrons
- Movement of electrons
Energy conservation
The law of conservation of energy states that energy cannot be created or destroyed only transformed from one form to another
System
Is the chemical reaction, energy is absorbed or released by the system. (Bonds are broken or formed between atoms)
Surroundings
Everything else, energy leaves the system and enters the surrounding and leaves the surrounding and enters the system.
Energy changes during chemical reactions (REACTANTS AND PRODUCTS)
Reactants - certain amount of chemical energy stored between bones
Product - Different amount of chemical energy due to different bonds
Seperate
When particles are separated, energy is needed.
Separated particle will have more energy than when they are together.
Forming
When particles are formed, energy is lost
Formed particles will have less chemical energy than the separated particles
Exothermic reactions
- GAS - LIQUID - SOLID
- Chemical reaction in which energy is released.
- Total Energy of the products is less than the total energy of the reactants
- Enthalpy change will be negative
- Energy ‘lost’ will be released to the surroundings.
- Energy is written on the product side of the chemical reaction.
Example - Combustion
Endothermic reactions
- Solid - Liquid - Gas
- Chemical reaction where energy is absorbed.
- Total amount of energy of the products is greater than the total amount of energy of the reactants.
- Chemical reaction in which energy is absorbed by its surroundings.
- Enthalpy change is positive.
- Energy is written on the right side of the chemical reactions.
Example - Photosynthesis
Energy profile diagram
Diagram that represents energy changes that occur during the course of a reaction
Thermochemical EQ Def
Chemical EQ that include energy changes mainly in the form of heat.
Enthalpy
The total amount of stored energy (kinetic and chemical potential) in a chemical reaction.
Change in enthalpy
Delta H
H(products) - H(reactants)
Exchange of heat between systems and its surroundings.
Activation energy
The energy required to break bones of reactants so that a reaction can proceed and start.
Relative Mass
Mass of an atom compared to carbon 12
Relative molecular mass
Total mass of all the atoms in a molecule added together.
Relative formula mass
Total mass of all the atoms in a compound’s formula, added together. used from ionic compounds.
Moles
Si based counting unit for the amount of a substance,
