Thermodynamics and Rate reactions note Flashcards
Spontaneous reactions are? and they tend to have high or low system energy?
Reactions that occur without help, and act on their own once their conditions are met. They tend to have lower system energy
examples
rust, ice cube melting, dissolving salt in water
Non -spontaneous reactions
Non spontaneous reactions only occur with external aid
ex heat, light, electricity
example of this is
sodium and chloride naturally react together to form NaCl, but we can reverse this process only with the help of energy.
Collision theory states
reactions occur when
1) particles collide
2) enough energy to overcome electron repulsion
3)correct orientations allowing the electron orbitals to overlap
types of collisions in collision theory
effective collisions - breaking bonds and forming new ones
Non- effective collisions - does not create new bonds
Why is the maxwell boltzmann Distribution important?
This distribution is important because it demonstrates the different speeds of particles and the kinetic energy required in order to break through the activation energy to form a reaction, it also highlights that as the temperature increases, the curves becomes flatter, highlighting the increase in particles that now have enough energy to react
Activated complex definition
The activated complex is the complex formed when the reactants have just reached the amount of energy required to start to form the products
When the Ea is small the reaction tends to be ____ when the Ea is large the reaction tends to be
Faster and exothermic(spontaneous) , Endothermic and slower(non spontaneous)
what are some of the reasons heat is released in water when bonds are formed
An exothermic reaction such as the formation of makeshift bonds can occur
makeshift bonds are where water molecules are attracted to the charged ions from the substance that is being dissolved and form bonds which release heat
if youre given the enthalpy of the reactants and the enthalpy of the products how can you measure change of enthalpy
enthalpy of products - enthalpy of reactants
Define hess law and why does it work
Hess law states that a reaction can occur in one step or multiple steps. This works because enthalpy is a state function meaning the systems enthalpy is independent from its history
NaOH + H20 —> Na + H2O + Heat
why is heat produced in this reaction
since we are dissolving NaOH in water, the ions present after the dissociation will cause water molecules to be attracted to these formed ions, forming make shifts bonds that release heat.
Enthalpy of formation is simply
the amount of energy released or absorbed to make a compound from its elements
