Kinetics, Equilibria And Redox Reactions Flashcards
Reaction rates, reversible reactions, Kc (equilibrium constant) and redox
Define rate of reaction
Change in concentration of a reactant or product over time
How do you calculate rate of reaction?
Around of reactant used or product formed ÷ time
What is collision theory?
Particles must collide with sufficient energy and the correct orientation in order to react
What is activation energy?
Minimum amount of kinetic energy for particles to react
What affects the rate of reaction (four things)?
Temperature, concentration, pressure and presence of a catalyst
What is the area under the curve on a Maxwell-Boltzmann distribution graph?
The total number of molecules
What does the peak of a Maxwell-Boltzmann distribution curve represent?
Most likely energy of a single molecule
Why does a Maxwell-Boltzmann distribution curve start at (0,0)?
No molecules have 0 energy
Name three different ways to measure a reaction
Timing how long a precipitate takes to form, measuring a decrease in mass, measuring the volume of gas given off
What is a dynamic equilibrium?
When the concentrations of reactants and products stay constants, this only happens in a closed system.
What is a closed system?
One in which nothing can get in or out.
State le Chatelier’s principle
if a factor affecting the position of an equilibrium is altered the position of the equilibrium shifts to oppose the effect of the change.
What is the difference between a homogeneous catalyst and a heterogeneous catalyst?
homogeneous = same state as the reactants, heterogeneous = different state to the reactants.
What is the catalyst used in a catalytic converter?
Platinum and rhodium
How does a catalyst work?
The gasses form weak bonds with the metal atoms of the catalyst (adsorption) and then the products break away to make more room for gasses (desorption)
How do you know if something is in equilibrium?
the rates of the forwards and reverse reactions are the same ad the net concentrations of the components will remain constant.
How will increasing the temperature affect the equilibrium?
Favours the endothermic reaction so that the extra heat is absorbed.
how will increasing the pressure affect the equilibrium?
Shifts the equilibrium to the side with the fewer moles of gas.
How will increasing the concentration of the reactant affect the equilibrium?
Gets rid of the extra reactant by making more product.
what is Kc in terms of ratio?
The ratio of products and reactants.
What causes changes to Kc?
Temperature
What will happen to Kc if there is more product at equilibrium?
Increase
What is a disproportionation reaction?
The simultaneous reduction and oxidation of one element.
What is an oxidising agent?
causes the oxidation (loss of electrons) off another substance and is itself reduced (gains electrons).
