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What does the law of conservation of energy state?
Matter cannot be created nor can it be destroyed
What is the system of a reaction?
The substances directly involved in the reaction, including reactants and products
What is the surroundings in a reaction?
Everything outside of the system being studied
What is enthalpy?
The measurement of energy in a thermodynamic system
What is △H?
The change in enthalpy
Negative for exothermic
Positive for endothermic
What is temperature?
The measurement of average Kinetic Energy of a molecule or atom
Characteristics of endothermic reactions
Energy gained from surroundings
Feels cooler
Bonds of reactants > products
Characteristics of exothermic reactions
Energy lost to surroundings
Feels warmer
Bonds of reactants < products
What is the reaction rate?
A measure of the rate at which reactants are consumed and products are formed
What is needed for a successful reaction to occur? (collision theory)
Particles must collide;
at a suitable orientation;
with sufficient energy
What is activation energy? Why is it significant to reaction rate?
The minimum amount of energy that must be possessed by the reacting substances in order to form products
If activation energy is not enough, the reaction cannot occur naturally and requires input of additional energy
How does activation energy relate to the likelihood of a reaction occurring spontaneously?
If a reaction has a high activation energy, it is less likely to occur spontaneously. This indicates it is a slow reaction, requiring external energy input
If a reaction has a low activation energy, it is more likely to occur spontaneously. This indicates it is a fast reaction, not requiring external energy input
What is the transition state of a reaction?
The highest energy state for the reacting system:
corresponds to the stage where bond breaking and formation is taking place
is unstable, only existing momentarily as products are either being formed or broken
How are reaction rates affected by different factors?
Nature of reactants: strong/weak bonds
State of subdivision: size of reacting particles
Concentration: amount of particles in a given volume
Gas: in gaseous phase, more surface area
Temp: can 1) increase rate of reaction 2) increase number of sufficient particle collisions
