rates, equilibrium and stoichiometry

• open system: matter and energy can be exchanged with surroundings
• closed system: energy (no matter) is exchanged with surroundings
• reversible reactions: reactions that do not go to completion
• endothermic reactions are more significantly impacted by temperature
• in a closed system, reversible reactions can reach an equillibrium
• macroscopic = things you can see and measure
• at equilibrium macroscopic properties remain the same
• k = concentration of products / concentration of reactants
• K = the equilibrium constant at a particular temperature
• is the temperature of a reaction changes the equilibrium constant also changes
• Le Chatelier's principal: if an equilibrium system is subject to a change then the system will adjust to partially oppose the change and re-establish equilibrium
• moles = number of particles / avagadro's number
• moles = mass / molar mass
• concentration = number of moles / volume
• percentage composition: (mass of solute / mass of solution) x 100
• ppm = mass of solute in mg / mass of solution in kg
• c1 v1 = c2 v2
• percentage purity = (mass of pure / mass of impure sample) x 100
• PV = nRT
• %yield / efficiency = (mass (or moles) of product obtained / theoretical mass (or moles)) x 100
• transition state = highest enthalpy for the reacting system
• transition state is unstable
• exothermic = negative enthalpy change
• endothermic = positive enthalpy change
• carbonic acid ionises in water