Concentration Units:

Concentration in (g.dm^-3) = mass of a solute in grams / volume of a solution in dm³

Percentage:

Mass by mass: ∴ (m/m) % = (mass of solute in g / mass of solution in g) x 100

Volume by mass: ∴ (v/m) % = (volume of solute in cm³ / mass of solution in g) x 100

Volume by volume: ∴ (v/v) % = (volume of solute in cm³ / volume of solution in cm³) x 100

Molarity:

Molarity, M, is defined as the number of moles of solute divided by the number of litres of solution

∴Molarity = M = 𝑚𝑜𝑙𝑒𝑠/𝑣𝑜𝑙𝑢𝑚𝑒 𝑖𝑛 𝑙𝑖𝑡𝑟𝑒𝑠 = n/v

Mole fraction:

Mole fraction, χ , which is defined as the number of moles of solute divided by the total number of moles, is also an expression of concentration.

∴ Mole fraction of component A = χA = 𝑚𝑜𝑙𝑒𝑠 𝑜𝑓 𝐴 / 𝑠um of moles of all components = nA/nT

Molality:

Molality (m) is the number of moles of solute dissolved in 1 kg (1000 g) of solvent:
∴ Molality = m = moles of solute /𝑚𝑎𝑠𝑠 𝑜𝑓 𝑠𝑜𝑙𝑣𝑒𝑛𝑡 (𝑖𝑛 𝑘𝑔)

Solubility:

Solubility is defined as the number of grams of the solute dissolved in 100 g of a solvent to prepare a saturated solution at a particular temperature.

Following are the factors which affect the solubility of solute

The general principle of solubility is, like dissolves like.

The ionic and polar substances(solutes) are soluble in polar solvents because they are like same e.g., KCl, Na₂CO₃ CuSO₄, sugar and alcohol are all soluble in water.

Non-polar substances are not soluble in polar solvent because they are unlike e.g. gasoline or oil are not dissolved in water.

Non-polar covalent substances are soluble in non-polar solvents mostly organic solvents). Grease, paints, naphthalene are soluble in ether or carbon tetrachloride etc.

Solute-solvent interaction.
To dissolve one substance (solute) in another substance (solvent) following three events must occur :

Solute particles separation
Solvent particles separation to provide space for solute particles.
Solute and solvent particles attract.

Temperature: The effect of temperature is same in solid and liquid but different in gases.

1. For solids and liquids: solubility is directly proportional to the temperature in solids and liquids

2.For gases: gas solubility typically decreases as temperature increases.

(a) The small bubbles of air in this glass of chilled water formed when the water warmed to room temperature and the solubility of its dissolved air decreased.

(b) The decreased solubility of oxygen in natural waters subjected to thermal pollution can result in large-scale fish kills.