Chemistry I

Solutions and Molarity

Molarity = moles of solute liters of solution

M = mol L

Practice Problem: Answer:

if M = mol L

M = 0.17 M

Practice Problem:

2.50 mL = 0.0025 L 58.5 mg = 0.058 g

if M = mol L

M = 0.396 M

M1V1 = M2V2

M1 = original molarity of the concentrated solution;
V1 = unknown volume needed to dilute; M2 = new molarity wanted of the new solution;
V2 = new volume wanted of the new solution.

Titration Example

Step 1: Write a balanced equation: HCl + NaOH ---> NaCl + H2O Step 2: Find the number of moles of the base: M = mol so, mol = (M)(L) = (2.0 M)(0.0397 L) = 0.078 mol NaOH L (because the ratio of NaOH to HCl is 1:1, then 0.078 mol is also the number of moles of HCl) Step 3: Calculate the concentration of HCl using the number of moles from Step 2 and the volume of the acid used. M = mol = 0.078 mol HCl = 3.12 M HCl L 0.025 L

Test Review -

  • Be able to work Molarity = mol/L problems.
  • Be able to work dilution problem.
  • Be able to calculate the number of grams needed to make a specific molarity solution from a solid.
  • Multiple Choice Questions (know the following): miscible, immiscible, solute, solvent, solubility, saturated, supersaturated, unsaturated solutions, concentration, molarity
  • Given graphs like the ones on page 504 and 505, be able to make some predictions and conclusions.
  • True and False questions over gases.