Example problem: What is the molarity of a solution containing 0. 75 mol NaCl in 4. 2 liters?

Example problem: What is the molarity of a solution containing 0. 75 mol NaCl in 4. 2 liters?

Example problem: Moles = 0. 75 mol NaCl Volume = 4. 2 L

Example problem: molarity = moles of solute / liters of solution = 0. 75 mol / 4. 2 L = 0. 17857142

Example problem: 0. 179 M NaCl

Example problem: What is the molarity of a solution made by dissolving 3. 4 g of KMnO4 in 5. 2 liters of water?

Example problem: What is the molarity of a solution made by dissolving 3. 4 g of KMnO4 in 5. 2 liters of water?

Example problem: Mass = 3. 4 g KMnO4 Volume = 5. 2 L

Example problem: Molar mass of K = 39. 1 g Molar mass of Mn = 54. 9 g Molar mass of O = 16. 0 g (The solute contains 4 O atoms, so count the 16g 4 times. ) Total molar mass = K + Mn + O + O + O + O = 39. 1 + 54. 9 + 16 + 16 + 16 + 16 = 158. 0 g

Example problem: grams of solute * (1/molar mass of solute) = 3. 4 g * (1 mol / 158 g) = 0. 0215 mol The grams units of the solute and solute mass cancel each other out so you are left with mol units.

Example problem: molarity = moles of solute / liters of solution = 0. 0215 mol / 5. 2 L = 0. 004134615

Example problem: 0. 004 M KMnO4

Example problem: What is the molarity of a solution containing 1. 2 moles CaCl2 in 2905 milliliters?

Example problem: What is the molarity of a solution containing 1. 2 moles CaCl2 in 2905 milliliters?

Example problem: Moles = 1. 2 mol CaCl2 Volume = 2905 ml

Example problem: 2905 ml * (1 L / 1000 ml) = 2. 905 L

Example problem: molarity = moles of solute / liters of solution = 1. 2 mol CaCl2 / 2. 905 L = 0. 413080895

Example problem: 0. 413 M CaCl2

Mass = 5. 2 g NaCl Volume = 800 ml water

The molar mass of Na = 22. 99 g The molar mass of Cl = 35. 45 g The molar mass of NaCl = 22. 99 + 35. 45 = 58. 44 g

Moles NaCl = 5. 2 g NaCl * (1 mol / 58. 44 g) = 0. 08898 mol = 0. 09 mol

You could also look at it as multiplying 800 ml by a conversion factor of 1 L / 1000 ml. To hasten the process, you could simply move the decimal point three places to the left instead of multiplying or dividing anything. Volume = 800 ml * (1 L / 1000 ml) = 800 ml / 1000 ml = 0. 8 L

molarity = moles of solute / liters of solution = 0. 09 mol / 0. 8 L = 0. 1125 mol/L

Answer: 0. 11 M NaCl