Solutions and Solubility
Lesson 1: Success Criteria
• By the end of today:
• Describe different types of solutions using scientific
vocabulary.
• Be able to properly make a solution of a specific molar
concentration.
Simulation – Salt & Solubility Phet
Which ones are solutions?
• Tea
• Stainless Steel Spoon
• Hand Sanitizer
• Hand Lotion
Solution Concentration
• Dilute:
• A dilute solution is one which contains a relatively
small amount of solute compared to the amount of
solvent.
• Concentrated
• A concentrated solution contains a large amount of
solute compared to the amount of solvent.
• How can you make a concentrated solution more
dilute?
• Add solvent
• How can you make a dilute solution more
concentrated?
• Add solute
Ho
mo
Ho
co
• Miscible:
• When liquids can mix in a proportion to form a
homogeneous solution (eg. Ethanol and water)
• Immiscible:
• When substances are added together they DO NOT
form a homogeneous mixture (eg. Oil and water)
• Saturated
• One which contains the maximum amount of solute that can be
dissolved in a given amount of solvent at a particular temperature.
• Unsaturated
• One which contains less than the maximum amount of solute that can
be dissolved in a given amount of solvent at a particular temperature.
• Supersaturated
• A solution with more solute than a saturated solution
How can you tell if a solution is saturated, unsaturated or supersaturated?
•
•
•
Saturated: If you add more solute it will not dissolve
Unsaturated: If you add more solute it will dissolve.
Supersaturated: If you add more solute it will crystallize
Success Criteria
• To be able to prepare aqueous solutions using both
methods – dissolving a solid in a solvent and diluting
a solution of known concentration.
Concentration
• Concentration is the amount of solute per unit of
solution. It is expressed as a ratio of the amount of solute
over the total amount of the solution.
• The different amounts of solute and solution can be
expressed in different units.
• Mass (µg, mg, g, kg)
Volume (µL, mL, L)
• To find the concentration of an unsaturated solution:
Amount of solute x magnitude ratio
Total Amt of Solution
solvent­
Molar Concentration
Molar Concentration
The method of measuring concentration • used most often in chemistry is molar The method of measuring concentration
used most often
in chemistry is molar
Ex. 3.0 mol HCl concentration.
concentration. L
Eg. 3.0 mol/L HCl
Molar = Moles of solute (mol)
Molar
= Moles of solute (mol)
concentration Volume of the solution (L)
Concentration
Volume of the solution (L)
Known as Molarity and it’s
unit is represented by M.
c =
n .
V
Preparing Solutions in the Lab
There are 2 ways to prepare a standard solution. Preparing Solutions in the Lab
• There are 2 ways to prepare a standard solution.
• Method 1 – make a solution from a solid solute
c = n/V
c = concentration
(mol/L)
n = moles (mol)
V = volume (L)
• Method 2 – dilute a concentrated solution
c1V1 = c2V2
c1 = initial concentration
V1 = initial volume
c2 = final concentration
V2 = final volume
Making a Solution in the Lab
1.
2.
3.
4.
5.
6.
7.
8.
9.
Clean a stopper and volumetric flask with lab soap and rinse well with
distilled water.
Fill the flask 1/3 full with distilled water.
Use the volume of the volumetric flask to calculate how much solute
you need to add to it.
Measure out the solute using one of the methods on the next slide and
transfer all the solute to your volumetric flask.
Swirl the mixture in the flask until the solute is dissolved
Add distilled water to the flask until the bottom of the meniscus is just
below the line on the neck of the flask.
Use a wash bottle of distilled water to add water drop by drop until the
bottom of the meniscus is exactly on the line.
Stopper and invert the volumetric flask 20 times.
Label your solution in mol/L. Include your name, the recipe and the
date prepared on the label.
Making a Solution in the Lab
When dissolving/dissociating a solid
solute
i)
Use c=n/V to calculate the mass of
solute you need to add to the flask.
ii) Measure out the mass of solid into a
small, clean, dry beaker using a
scoopula and a balance.
iii) Add the solute in the beaker to the
water in the volumetric flask using a
funnel.
iv) Ensure all solid is transferred from
the beaker to the flask by rinsing the
beaker with distilled water and
adding the rinse water to the
volumetric flask at least 2 times.
When diluting a solution
i)
Use C1V1 = C2V2 to calculate the
volume of solute you need to add to
the flask.
ii) Measure out the volume using a
graduated or volumetric pipette and
bulb and transfer it to the volumetric
flask.
Ex. 2
How would you make a 2.0 mol/L solution of C6H12O6 in a 50 mL volumetric flask?
Calculations
Method 1: Dissolving a Solid
1.
Find the molar concentration of a 3.0L solution with 4 moles of
NaCl dissociated in it.
Ex.3
The molar concentration of sugar cane, C 12 H22 O11 in a 355 mL can of Coke is 0.32mol/L. 2. How would you make a 2.0mol/L solution
of C6H12O6 in a 50mL
a) Find the number of moles of sugar in the can.
volumetric flask?
b) If you drank the whoole can, what mass of sugar would you 3. The molar concentration of sugar cane,
C12H22O11 in a 355mL can of
consume?
Coke is 0.32mol/L.
a)
b)
Find the number of moles of sugar in the can.
If you drank the whole can, what mass of sugar would you consume?
Making a Solution in the Lab
Method 2: Diluting a concentrated Solution
1. You are given a concentrated solution of 1.25
mol/L sodium chloride in water. What volume of
this concentrated solution must you add to make
50mL of a 1.00mol/L NaCl solution.
2. You are given a 0.45mol/L concentrated sugar
solution. How much concentrated sugar solution
do you need to add to a 25mL volumetric flask to
make a 0.25mol/L solution?
Recall – Net and Total Ionic Equations
KCl(aq) + AgNO3(aq) --> KNO3(aq) + AgCl(s)
Total
Ionic
Equation
TotalEquation
I onic Equation
Total
I onic
NetIonic
I onic Equation
Net
Net I onic Equation Equation
Other Units of Concentration
Concentration
Stoichiometry in Solutions
• Success Criteria:
• Be able to use stoichiometry to solve problems
involving solutions and solubility.
Example 1
• What is the minimum volume of 0.25mol/L
MgCl2(aq) needed to precipitate all of the silver ions
in 60.0mL of 0.30 mol/L solution of silver nitrate.
Assume silver chloride is completely insoluble.
Example 2 – Limiting Reactant
• Calculate the mass of solid Ag2CrO4 that forms
when 50.00mL of 0.100M AgNO3 reacts with
50.0mL of 0.150mol/L sodium chromate.
Learning Check
• What is the minimum volume of 0.25 mol/L
MgCl2(aq) needed to precipitate all the silver ions in
60.0mL of a 0.30mol/L solution of silver nitrate.
Assume silver chloride is completely insoluble.