January 5 2011---Molarity

Molarity is a measure of concentration of a solute in a solution or of any chemical species in terms of amount of substance in a given volume.  The unit for molarity is mol/L.  A solution of concentration 1 mol/L is also denoted as 1 molar (1 M). 


To calculate molarity you use this forumula : Molar Concentration (M) = moles of solute(mol)/Volume of solution (L)

Eg.


1. How many grams of solute are present in 175 mL of 0.67 M glucose (C₆H₁₂O₆)?

0.67M/L * 0.175L * 180g/mol = 21.11g

2. How many grams of MgBr₂ should be dissolved in 275 mL of solution to produce a 0.32 M solution?

0.32M/L * 0.275L * 180g/mol = 15.84g

3. What volume of 12.4 M HCl would you need to make 500.0 mL of 3.50 M HCl?

(12.4M) * V = (0.500L)(3.50M)
V = .141 L = 14.1 mL

4. How many mL of 0.24 M KCl solution contains 0.56 g of KCl?

0.24 M * 0.56 g * 1 mol/74g = .0018 mL


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