CONCENTRATIONS
MIXTURES WITH WATER
• Solution:
• Tiny particle size (between <1 nm)
• Solute: Thing being dissolved
• Solvent: Liquid solute is dissolved in
• Solute + Solvent = Solution
• Example: Kool-Aid
CONCENTRATION
• Concentration:
• When a solution is made, the
concentration can be
measured.
• Concentration is the amount
of solute dissolved in a given
amount of solvent
• Which solution has a higher
concentration?
• If this was sugar water, how
could you tell?
• If this was food coloring in
water, how could you tell?
EXPRESSING CONCENTRATION
• 1. Percent by Mass
•
Mass
%Mass=
Solute
MassSolution
• Ex: There are 85 g of KCl in 150 g of Water.
What is the % Mass of KCl?
YOU TRY
• Ex: You have a 3.90% by mass solution of
sodium chloride and water. The solution has
a mass of 43 g. What is the mass of NaCl in
the water?
MassSolute
%Mass=
MassSolution
EXPRESSING CONCENTRATION
• 2. Parts Per Million (ppm)
• Given a % Mass, we can use a proportion to
convert it to ppm
• Ex: Iron makes up 0.00085% of a sample of
water. How many ppm is the iron?
0.00085
x
=
100
1, 000, 000
x = 8.5ppm
EXPRESSING CONCENTRATION
• 12 g of cobalt is dissolved in acid to make a
539 g solution. What is the concentration of
cobalt in ppm?
EXPRESSING CONCENTRATION
• 3. Molarity (M)
• Compares moles of solute per L of solution
mol Solute
Molarity =
Lsolution
• Ex: What is the concentration if you dissolve
45 g of NaCl to make a 1.5 L solution?
CONCENTRATION – YOU TRY
• What is the concentration if you dissolve
38.7 g of LiF to make a 3.4 L solution?
mol Solute
Molarity =
Lsolution