In Mole Calculations, many students lose marks in questions related to Volumetric Analysis, especially on those that requires them to understand the concepts of CONCENTRATIONS of solutions. Volumetric Analysis are always a highlight in our annual Mole Calculations Mastery Workshop.
Concentrations of a solution refers to the amount of solute dissolved in 1 dm3 of the solution.
Do note that:
Solution = Solute (minor component) + Solvent (major component)
Usually in basic chemistry such as O Levels, the solvent used is Water. As such, the solution formed is usually aqueous solutions whereby certain solid or liquid are dissolved in water.
Concentrations can be expressed in:
- Grams of solute per dm3 (unit will be g/dm3)
- Moles of solute per dm3 (unit will be mol/dm3)
The most important formulae student need to know in volumetric analysis are:
Conc. (mol/dm3)? = Amt. of Solute (mol) / Vol. of Solution (dm3)
&
Conc. (g/dm3)? = Amt. of Solute (g) / Vol. of Solution (dm3)
Let’s check out a question to see how we can use the formulae above.
Question:
60g of NaOH is dissolved in water and make up to the total volume of 500cm3. Calculate the [Read more…] about O Level Chemistry: Mole Calculations – Concentrations of Solutions