Calculating concentration

What are six methods of representing concentration?

1. Molarity ($M$)
   • Moles of a substance per liter of solution
2. Molality ($m$)
   • Moles of a substance per kilogram of solution
     • $m$ stays constant irrespective to temperature and pressure
3. Normality ($N$)
   • Moles of equivalents per litre of solution that can donate or accept one mole of protons: That is, one mole of NaOH in one mole of water is not only a 1 $M$ solution, but also a 1 $N$ solution because one mole of NaOH can accept one mole of protons.
   • Normality is often used in red-ox or acid/base calculations
4. Mass percentage (% by mass)
   • Mass of a substance in a mixture as a percentage of the entire mixture's mass
5. Volume percentage (% by volume)
   • Volume of a substance in a mixture as a percentage of the entire mixtureÕs volume
6. Mole fraction (molar fraction)
   • Number of moles of a substance as a proportion of the total number of moles in a mixture