Inquiry Q#1: What Happens When Chemical Reaction Dont Go Until Completion? Flashcards
What is a reversible reaction?
When products of reactions can react and reform the original substance
For example: cobalt(II) chloride can go from hydrated to dehydrated and then be reversed back to hydrated by adding water
COCl2 + H2O <> COCl2 +2H2O
Purple. Blue
Also: NO2(g) <> N2O4(g)
Reddish brown. Colourless
What are examples of reaction that go until completion?
4Fe + 3O2 —> 2Fe2O3
2Mg + O2 —> 2MgO2
What is a static equilibrium?
Where rates of both forward and reverse reactions are zero
What is a dynamic equilibrium?
Where rates of both forward and reverse reactions are equal
What is an open systems?
One which interacts with its environment - this means both energy and matter can move in and out of the system
What is an closed system?
Energy may still be able to flow in and out between the system and environment, it matter cannot enter of leave the system
Closed systems are the only systems which reach equilibrium
What is a non-equilibrium system?
An irreversible reaction that goes until completion and cannot ever reach equilibrium or be balanced
What is entropy?
A measure of ways in which energy can be distributed in a system of molecules. The higher the entropy the more disordered the energy e.g. gas is more disordered then liquid which is more disordered then solid
Symbol= S
Units =Jmol-1k-1
What is enthalpy?
The total energy in a system. Often measured by the difference of reactants and products
Symbol=H
Units= KJmol-1
What is Gibbs free energy?
A method of combining enthalpy and entropy to be able to predict spontaneity Symbol = delta G Equation = G= ^H - T^S Positive G = not spontaneous Negative G = spontaneous
What is a combustion reaction?
Non-equilibrium reaction because it cannot be reversed so cannot reach equilibrium in a closed system.
What is a photosynthesis reaction?
This is an irreversible endothermic reaction. Even though respiration looks like the reverse of photosynthesis they are 2 different reactions. Each go to completion and don’t reach equilibrium
6CO2(g) + 6H20(l) —> C6H12O6(aq) + 6O2 (g)
What is the collision theory?
For a reaction to occur, the particles must collide with enough energy to break bonds and have the appropriate orientation to allow the bonds to form.
What is reaction rate?
The speed at which a chemical reaction takes place
What is the relationship between the collision theory and reaction rate?
The more successful collisions the faster the reaction rate. This can be dependent on concentration in a reversible reaction with all other factors kept constant.
