In this lesson, we will learn:
- To apply our understanding of moles calculations to solutions.
- To understand the difference between molarity, moles, and mass.
- To be able to calculate molarity of chemicals dissolved in solution.
- To be able to calculate amounts of substance from titration problems.
- You cannot use the molar volume of gas constant (22.4 L / mol at STP) if your question is about a solution or is not at standard temperature and pressure (STP). It is only used when dealing with gases at STP.
- The same goes for RTP molar volume if not at RTP.
- Molarity means concentration, for chemists - it means the amount of moles of a chemical per amount of volume. For example, in a given volume of solution.
- Units of concentration are abbreviated “M”. It means moles per litre, written mol / L or mol L or moles per cubic decimeters, written mol / dm or mol dm.
- Square brackets, e.g. [HCl] are used to show that the concentration of a chemical is being referred to.
- You can use the formula to find concentration, where = number of moles and is volume (in liters, L, or cubic decimeters, written dm). You can re-arrange for .
- A titration is an experiment used to find out the unknown concentration of an acid by reacting it with a base of known concentration, or vice versa (unknown base with known acid). This lesson covers titration calculations, not the titration method or procedure.
- When answering molar concentration questions, make sure you convert your units properly – volume is often given in mL but concentration is measured in moles per litre!