Transcript Molarity and Dilutions

Molarity and Dilutions
If I take 23 grams of sucrose and dissolve it into
100.0mL of water, how many moles per liter do I have?
What would we need to do or know in order to solve this problem?
Molarity
The name used for moles per liter.
It is represented by M
It is a type of concentration:
◦A part of something mixed into the whole of
something.
◦ Parts of solute in liters of a solution.
Other types of concentrations:
Percent concentration: the % of solute parts per the
% of solvent parts.
◦Example: 61% ethyl alcohol in hand sanitizer
Molality: (m) the number of moles of solute per
kilogram of solvent.
◦Example: 0.60 moles of NaCl dissolved in 1.50 L of water is
0.4 m NaCl
Review: Label the three pictures:
solution, solvent, solute
Molarity Equation:
Molarity (M) = Moles of solute
Liters of solution
Let’s try some
practice problems
If a flask of 5.0M solution of CaCl2 has 0.034 grams
dissolved in it. How many L of solution is in the flask?
If 600.0 mL of water are added to 5.7 grams of sodium
carbonate, what is the molarity of the solution?
How many moles are in 500.0 mL of a
0.45 molar (M) solution of lithium oxide?
Molarity Warm Up: Period 1
Calculate the molarity of a 400mL solution that is made up of 5.19g
of cobalt (II) chloride.
What is the new molarity of the cobalt (II) chloride solution if I add
100mL to the solution?
Molarity Warm Up: Period 2
What is the molarity of a 200.0 mL solution with 16.34g iron (II)
sulfate?
How much water do I need to add to make it a .27M solution?
Warm Up: Period 3
What is the molarity of 200.0 mL solution of 11.3 grams of copper
(II) sulfate?
How much water do I need to add to make it a .23 M solution of
copper (II) sulfate?
Warm Up: Period 5
What is the molarity of a 200ml solution of 9.21g manganese (II)
chloride?
How much water do I need to add if I want to make that a .19M solution?
Warm Up: Period 6
What is the molarity of a 25mL solutions of 2.55g of Copper (II)
chloride?
What is the new molarity if I add 38mL of water to the solution?
What does dilute mean?
Dilutions
Once you know the molarity of a solution, you can
add water to it and predict the molarity of the new
solution. This is called a dilution.
“I diluted the sweet tea, it is not as concentrated
now.”
Dilution Formula
Molarity of solution 1 x the volume of solution 1 is equal to the molarity of solution 2 x the
volume of solution 2.
M1V1 = M2V2
Example: If 25mL of water is added to a 100.0mL of a 0.50 M solution of HCl,
what is the new molarity?
Let’s try some practice
dilution problems
If 500.0 mL of NaCl is diluted down to 600.0 mL of a
0.534 M solution, what was the original molarity?
How much water was added to a 300.0mL 4.5 M
solution of sulfuric acid to make it a 1.00 M solution?