Solutions: MolarityChemistryMs. Piela

• A. Concentration – measure of the amount of solute that is dissolved in a given amount of solvent

• I. Concentration of Solutions•Solutions: Molarity

• B. Dilute Solution – contains a lower concentration of solute

• C. Concentrated Solution – contains a higher concentration of solute

• B. Sometimes referred to as a molar solution (i.e. 0.5 molar solution

• II Molarity• Solutions: Molarity

• A. The most important unit of concentration in chemistry

• The number of moles of solute dissolved per liter (L) of solution

• C. To determine molarity, DIVIDE the number of MOLES by the volume in LITERS

D. Example Problems

1. What is the molarity of a solution that contains 2.0 mol of glucose in 5.0 L of water?

0.4 M

• II Molarity• Solutions: Molarity

D. Example Problems2. A saline solution contains 0.90 g NaCl in exactly 0.100 L of solution. What is the molarity of the solution?

0.20L

• II Molarity• Solutions: Molarity

D. Example Problems

3. How many moles of solute are present in 1.5 L of 0.24 M Na2SO4?

0.36 mol

• II Molarity• Solutions: Molarity

•Solution Stoichiometry• Stoichiometry calculations can be done using molarity and volumes.• Since stoichiometry just depends on mole ratios, the goal is to find moles!

•Example Problem #1

•Calculate the number of mL of 2.00 M HNO3 solution required to react with 216 grams of Ag according to the equation.

3 Ag(s) + 4 HNO3 (aq) → 3 AgNO3 (aq) + NO(g) + 2 H2O(l)

•Example Problem #2

•Calculate in mL the volume of 0.500 M NaOH required to react with 3.0 grams of acetic acid (HC2H3O2). The equation is:

NaOH (aq) + HC2H3O2 (aq) → NaC2H3O2 (aq) + H2O(l)

•Example Problem #3

•Calculate the number of grams of AgCl formed when 0.200 L of 0.200 M AgNO3 reacts with an excess of CaCl2. The equation is:

2 AgNO3 (aq) + CaCl2 (aq) → 2 AgCl(s) + Ca(NO3)2 (aq)