Concentration - means by which amount of material in a given quantity of solution is expressed.
If molecules are distributed on a molecular basis, system is referred to as a solution, and the dissolved material is the solute.
We usually use the term solution to refer to solutes in a liquid solvent.
If the materials are dispersed as particles, the system is referred to as a suspension or dispersion.
Molecule is big, 10Angstroms, lots of atoms make it.
In between = colloids 10-1000nm
Molarity - number of moles of solute in 1L of solution
Molality - number of moles of solute in 1000g of solvent
Mole fraction - is the number of moles of solute divided by the total number of moles of solute and solvent.
% w/v - g of solute in 100ml solution
% w/w - g of solute in 100g of solution
Principles of Chemical Equilibrium
- Some reactions proceed to completion
- Many reach equilibrium whereby the rates of the forward and reverse reactions are equal (dynamic equilibrium)
- this is given by the equilibrium constant K.
- K= (Products)/(Reactants)
Law of Mass Action: Every Reaction has its own equilibrium constant expression
- aA + bB = cC + dD
- K= (C)^c(D)^d/(A)^a(B)^b
- constant at given temperature
- the equilibrium constant expression depends only on the stoichiometry of the reaction, not on its mechanism.
- if K is known, we can predict the concentrations at equilibrium
- K tells us the extent of the reaction
Free energy (G) - system will go from high to low free energy spontaneously until energy state of reactants and products the same (ΔG=0)
Chemical potential μ
How much does the free energy increase by adding 1 mole of a substance to a solution?
- High chemical potential - addition causes free energy to increase a great deal - results in high free energy for system
- Low chemical potential - addition causes free energy to increase only slightly
- Higher free energy of system = higher driver for spontaneous reaction
- Everything tries to lose its free energy to the surroundings.
2 materials (reactant…