# Solutions

Solutions

Distinguish between the terms solute, solvent, solution and concentration (g dm-3 and mol dm-3)

Solute This is the substance which has been dissolved.

Solvent The bulk substance in which the solute was dissolved

Solution This is made up of the solute and the solvent. The solution is called aqueous if the solvent is water

Concentration This is an expression of how much solute there is dissolved in the solution. This can be expressed in g dm-3 or mol dm-3.

Solve problems involving concentration, amount of solute and volume of solution C = concentration of solution – mol dm-3

n = number of moles of solute – mol

V = volume of solution – dm3

For example: Calculating Concentrations of Components of Solutions

The concentration of individual ions in solution is proportional to the chemical formula of the compound. If two or more solutions are mixed and there is no chemical reaction, the concentration of each individual ion can be calculated by determining the total amount of that ion present and dividing by the final volume of the solution.

For example: Dilution of Solutions

When a solution is diluted, the number of moles of solution remains the same, but the volume changes. c1 = initial concentration

V1 = initial volume

c2 = diluted concentration

V2 = diluted volume

For this equation to work, the units must be constant, not necessarily mol dm-3 or dm3

For example:  Limiting Reagent with Solutions   Finding Amounts of Products

 Substance Lead (II) Nitrate Potassium Iodide Volume 20.0cm3 excess Concentration 0.250mol dm-3 0.500mol dm-3 