Concentration | Chemistry for Grade 11 (IGCSE) PDF Download

Units of Concentration

• A solid substance that can dissolve in a liquid is termed a solute, while the liquid itself is known as a solvent. Together, they create a solution.
• Many chemical reactions occur within solutions, where solutes are dissolved in solvents, which could be water or organic solvents.
• Concentration denotes the quantity of solute present within a specific volume of the solvent.
• Higher concentrations are achieved when there's a greater amount of solute within the given volume.
• Solute quantity can be measured in grams or moles.
• Typically, concentration is represented as the amount of substance per cubic decimeter (dm³), leading to concentration units such as grams per cubic decimeter (g/dm³) or moles per cubic decimeter (mol/dm³).

Calculating Concentration

• Concentration refers to the quantity of solute present in a specific volume of the solvent.
• In the context of concentration, a common formula used to determine concentration in grams per cubic decimeter (g/dm³) is:
  

Measuring Concentration

• Concentration can be expressed in grams per cubic decimeter.
• One cubic decimeter (dm³) is equivalent to 1000 cubic centimeters (cm³), which is also equal to one liter.
• When converting data between cm³ and dm³:
  • To convert from cm³ to dm³, divide by 1000.
  • To convert from dm³ to cm³, multiply by 1000.

Calculating Concentration using Moles

• Expressing concentration in moles per unit volume is more beneficial for chemists compared to expressing it in mass per unit volume.
• Concentration can be quantified in moles per cubic decimeter (mol/dm³) using the formula:
  
• This formula can be adapted to include moles as a unit of concentration.
• The resulting units are typically written as mol/dm³, which can also be denoted as mol dm^-3.
• Conversion between grams per cubic decimeter (g/dm³) and mol/dm³ may be necessary depending on the question:
  • To convert from g/dm³ to mol/dm³, divide by the molar mass in grams.
  • To convert from mol/dm3 to g/dm³, multiply by the molar mass in grams.
• Some students find formula triangles helpful in understanding this relationship.