SolutionsIB Chemistry: Chapter 1 Section 1.5

What parts make up a solution?Solution is a mixture of two components.

1. Solute: less abundant component, the substance being dissolved

2. Solvent: more abundant component, the dissolver

Solutions in water are called aqueous (aq).

ConcentrationAs more and more solute gets dissolved, the solution becomes

more concentrated.

When the solvent can no longer dissolve any more solute, it is saturated. (If less solute is dissolved, unsaturated.)

Solution can dissolve more solute than usual under particular circumstances – supersaturated.

MolarityMolarity is a term we use to describe concentration.

M = mol/dm3, Molarity = moles (n) of solute dissolved in 1 dm3 of solution.

What is the molarity of 2.98g of NaCO3 in 500cm3 of solution?

DilutionsSometimes, we need a diluted solution for a particular

procedure.

In order to dilute, you add water to a more concentrated solution.

The equation we use to determine how much concentrated solution we need is:

M1V1=M2V2

Types of MixturesClassified by:

Size of the particlesWhether they exhibit the Tyndall effect

Types of Mixtures

Solution:Particles are evenly distributed and do not

separate on standingNo Tyndall EffectExample: food coloring and water mixture

Solution ExampleNotice how you cannot see a distinction between solute and solvent. It is the same throughout the solution.

Types of MixturesSuspensions:

Particles are not evenly distributed. Particles are suspended but will eventually settle into layers

Exhibits Tyndall EffectExamples: Dirt and water mixture

SuspensionsThe larger particles in a suspension settle out over time. Particles are only physically combined.

Types of MixturesColloids:

Particles are not evenly distributed. Particles are suspended but will eventually settle into layers

Exhibits Tyndall EffectExamples: Dirt and water mixture

ColloidsLooks like a solution to the naked eye. Particles are suspended. The particle size is the “in betweener”, larger than a solutions’ particles but smaller than a suspensions’ particles.

What is this “Tyndall effect”?Light scattering by particles.

Found in colloids and suspensions, but not solutions.

Tyndall Effect

Hydrates

Hydrates are ionic compounds that have water molecules absorbed into the crystal lattice.

Hydrates are still solid, just have certain amounts of water attached to the ions.

An example of a hydrate is Copper (II) Sulfate pentahydrate:CuSO4 ● 5H2O

HydratesAn example of a hydrate is:

CuSO4 5H2OThis means that for every 1 unit of copper sulfate, there

are 5 units of water.Or, for every 1 mole of copper sulfate there are 5 moles of

water.

Solve for the molar mass. (The dot does not mean multiply, just add the mass of water to mass of copper sulfate.)