Molar Concentration or "Molarity" of Solutions

Welcome back to The Biggest Noob Chemists blog. We wish you all a Happy New Year and hope you're ready for a new school term. Without further ado...let's begin our lesson.

So in today's class, we wasted no time in reviewing and went straight to learning something new. In this class Ms. Chen introduced us to Molar Concentration.

Molar Concentration/Molarity is basically the number of moles of solute in one Litre of a solution. Just a heads up to all of you, we use M to denote molar concentration.



We calculate Molar Concentration by using this formula.
Molar Concentration (M) = moles of solute(mol)/Volume of solution (L)

This formula can be flipped to find Moles and Litres also.

moles of solute (mol) =  Molarity(M) x  Volume of solution(L)
                                                and
Volume of solution (L) = moles of solute (mol)/Molarity(M)



Example. What is the molarity of 5.30g of Na2 CO3 dissolved in 400.0mL solution?

1. Step is we have to convert 400.0 mL in to litres. We do this by multiplying 400 by 10^3.

2. We now have 0.4 L

3. Next we use the formula to find out the Molarity.

5.30g x 1mole/106Na2CO3 = 0.05Na2CO3/0.4L = 0.125 mol/L

Here's a youtube video:

This concludes my post. Thanks for reading.


PH