STOICHIOMETRY
OF REACTIONS IN
SOLUTIONS
LOUIS ANDREW R. TAYAG
LEARNING COMPETENCY
USE DIFFERENT WAYS OF EXPRESSING CONCENTRATION OF
SOLUTIONS: PERCENT BY MASS, MOLE FRACTION, MOLARITY,
MOLALITY, PERCENT BY VOLUME, PERCENT BY MASS, PPM.
PERFORM STOICHIOMETRIC CALCULATIONS FOR REACTIONS IN
SOLUTION.
WHAT IS
CONCENTRATION?
WHAT IS CONCENTRATION?
It is the amount of solute present in
a solution.
COMMON UNITS OF CONCENTRATION
• Percent by mass
• Percent by volume
• Mole Fraction
• Molarity
• Molality
PERCENT BY MASS
Ratio of the mass of solute to the mass of the
solution multiplied by 100%
𝑚𝑎𝑠𝑠 𝑜𝑓 𝑠𝑜𝑙𝑢𝑡𝑒
𝑚𝑎𝑠𝑠 𝑝𝑒𝑟𝑐𝑒𝑛𝑡 =
𝑥 100
𝑚𝑎𝑠𝑠 𝑜𝑓 𝑠𝑜𝑙𝑢𝑡𝑒 + 𝑚𝑎𝑠𝑠 𝑜𝑓 𝑠𝑜𝑙𝑣𝑒𝑛𝑡
𝑚𝑎𝑠𝑠 𝑜𝑓 𝑠𝑜𝑙𝑢𝑡𝑒
𝑚𝑎𝑠𝑠 𝑝𝑒𝑟𝑐𝑒𝑛𝑡 =
𝑥 100
𝑚𝑎𝑠𝑠 𝑜𝑓 𝑠𝑜𝑙𝑢𝑡𝑖𝑜𝑛
A sample of 0.678 g of sulfuric acid
is dissolved in 65 g of water. What is
the percent by mass of H2SO4 in the
solution?
A saline solution with a mass of 355
g has 36.5 g of salt dissolved in it.
What is the mass percent
concentration of the solution?
ppm
Ratio of the mass of solute to the mass of the
solution multiplied by 106
𝑚𝑎𝑠𝑠 𝑜𝑓 𝑠𝑜𝑙𝑢𝑡𝑒
6
𝑝𝑝𝑚 =
𝑥 10
𝑚𝑎𝑠𝑠 𝑜𝑓 𝑠𝑜𝑙𝑢𝑡𝑖𝑜𝑛
Find the concentration of calcium
ion (in ppm) in a 3.50 g pill that
2+.
contains 40.5 mg of Ca
Find the concentration of HCl (in
ppm) in a 20.50 g solution that
contains 4 g of HCl.
PERCENT BY VOLUME
Ratio of the volume of solute to the volume of the
solution multiplied by 100%
𝑣𝑜𝑙𝑢𝑚𝑒 𝑜𝑓 𝑠𝑜𝑙𝑢𝑡𝑒
𝑣𝑜𝑙𝑢𝑚𝑒 𝑝𝑒𝑟𝑐𝑒𝑛𝑡 =
𝑥 100
𝑣𝑜𝑙𝑢𝑚𝑒 𝑜𝑓 𝑠𝑜𝑙𝑢𝑡𝑖𝑜𝑛
Calculate the volume percent of a
solution that is prepared by
mixing 519.2 mL of helium and
168.4 mL of molecular chlorine.
What is the volume percent of a
solution that has 5.0 mL of
hydrochloric acid (HCl) diluted to
100 mL with deionized water?
MOLARITY
Number of moles of solute in 1 liter solution.
𝑎𝑚𝑜𝑢𝑛𝑡 𝑜𝑓 𝑠𝑜𝑙𝑢𝑡𝑒 (𝑚𝑜𝑙)
𝑀=
𝑣𝑜𝑙𝑢𝑚𝑒 𝑜𝑓 𝑠𝑜𝑙𝑢𝑡𝑖𝑜𝑛 (𝐿)
Calculate the molarity of 5.80 g of
LiNO3 in 505 mL of solution.
Calculate the molarity of 0.444 mol
of CoCl2 in 0.654 L of solution.
MOLALITY
Number of moles of solute in dissolved in
1kg of solvent.
𝑎𝑚𝑜𝑢𝑛𝑡 𝑜𝑓 𝑠𝑜𝑙𝑢𝑡𝑒 (𝑚𝑜𝑙)
𝑚=
𝑚𝑎𝑠𝑠 𝑜𝑓 𝑠𝑜𝑙𝑣𝑒𝑛𝑡 (𝑘𝑔)
Calculate the molality of a sulfuric
acid solution containing 24.4 g of
sulfuric acid in 198 g of water. The
molar mass of sulfuric acid is 98.09
g/mol.
Calculate the molality of a solution
prepared from 29.22 g of NaCl in
2.00 kg of water.
MOLE FRACTION
Number of moles of a component divided by
the total number of moles of a solution.
𝑎𝑚𝑜𝑢𝑛𝑡 𝑜𝑓 𝑠𝑜𝑙𝑢𝑡𝑒 (𝑚𝑜𝑙)
𝑋=
𝑎𝑚𝑜𝑢𝑛𝑡 𝑜𝑓 𝑠𝑜𝑙𝑢𝑡𝑖𝑜𝑛 (𝑚𝑜𝑙)
A sample of rubbing alcohol
contains 142 g of isopropyl
alcohol (C3H7OH) and 58.0 g of
water. What are the mole
fractions of alcohol and water?
Determine the mole fraction of
CH3OH and H2O in a solution
prepared by dissolving 5.5 g of
alcohol in 40 g of H2O.