Solutions Unit
April 15-April 26 (2016)
Day 1: Review of Solutions and Intro to Concentration
Objectives (SWBAT):
Physical Science 14- Identify unknowns as solutions, colloids, or suspensions based on physical properties
Physical Science 20- Express concentration in terms of percentages
Inquiry 5- Use mathematics to solve problems
Evaluated by:
Intro to Solutions and Concentration
Class structure:
Do Now: What is the definition of a solution?
1. Engage- Class will review the definition of a solution- a solute (usually solid or gas) dissolved in a solvent
(usually liquid) that forms a homogeneous mixture. Then the class will review old vocabulary termscolloid and suspension.
2. Explore- Students will compare and contrast solutions, colloids, and suspensions.
3. Explain- Students will draw a picture of each as reference and give at least two real world examples for
each type of mixture.
4. Elaborate- Teacher will explain that because solutions are evenly mixed we can discuss the amount of
solute in the solvent, called concentration and it will be the same throughout the mixture. Teacher will
introduce the first type of concentration, % by mass or volume. Students will calculate the molality for
various solutions.
Summary: When a substance (solute) dissolves in a liquid (solvent) to form a homogeneous mixture, the mixture is
called a solution. If the particles are too large to be homogenous but cannot be separated by gravity, the mixture is
called a suspension. If the mixture can be separated by gravity, it is called a colloid.
Day 2: Molarity and Dilutions
Objectives (SWBAT):
Physical Science 20- Express concentration in terms of molarity
Inquiry 5- Use mathematics to solve problems
Evaluated by:
Molarity and Dilutions Worksheet
Class structure:
Do Now: If hydrogen peroxide you buy at the store is only 3% H2O2, and you buy 500mL of it, what volume was hydrogen
peroxide and what volume was just water?
1. Engage- The teacher will introduce the idea that amounts, and therefore concentrations, can be
expressed in a variety of units and introduce molarity.
2. Explore- Students will calculate the molarity, number of moles, or volume of a solution using the
molarity definition.
3. Explain- Students will show all work.
4. Elaborate- Teacher will introduce the term dilute. Students will calculate new concentrations upon
dilutions and the amount of water needed for dilutions.
Summary: The concentration of a solution is a ratio of solute to solvent. The most commonly used ratio in Chemistry is
moles of solute to liters of solution. This is called molarity.
Day 3: Dilution Lab
Objectives (SWBAT):
Physical Science 20- Express concentration in terms of molarity
Inquiry 5- Use mathematics to solve problems
Evaluated by:
Dilution Lab
Class structure:
Do Now: What is the molarity of a solution of 35 g of CaCl2 dissolved in 200 mL of water?
1. Engage- Students will record observations of the stock solutions at the front of the classroom.
2. Explore- Students will prepare a 1.13 M solution of copper sulfate after checking their group members
for safety compliance.
3. Explain- Students will show all calculations and explain why the color of each dilution differs from the
original solution.
4. Elaborate- Students will evaluate their lab technique for possible sources of error.
Summary: Concentrated solutions can be made less concentrated by the addition of more solvent (water). This is called
dilution.
Day 4: Mini Quiz #3 and Molality/Colligative Properties
Objectives (SWBAT):
Physical Science 18- Given the concentration of a solution, calculate the predicted change in its boiling and freezing
point
Physical Science 20- Express concentration in terms of molality
Inquiry 5- Use mathematics to solve problems
Evaluated by:
Molality and Colligative Properties Worksheet
Class structure:
Do Now: Clear your desk for the Concentration Mini Quiz.
1. Engage- The teacher will review the idea that amounts, and therefore concentrations, can be expressed
in a variety of units and introduce molality.
2. Explore- Students will calculate the molality, number of moles, and volume of various relationships
based on the molality definition.
3. Explain- Students will show all their work. The teacher will explain that concentration affects properties
such as boiling point, freezing point, and conductivity- called colligative properties.
4. Elaborate- Students will calculate the change in boiling and freezing point for various substances.
Summary: The concentration of a solute in a solution affects the solution’s properties such as its boiling point (raises it),
freezing point (lowers it), and conductivity- called colligative properties.
Day 5: Electrolytes and Nonelectrolytes
Objectives (SWBAT):
Physical Science 19- Predict the conductivity of a solution
Evaluated by:
Electrolytes Worksheet
Class structure:
Do Now: Which would raise the boiling point of water the most: KI or CO2?
1. Engage- Class will discuss how tap water is different from distilled water. Teacher will show that one
conducts electricity (using a multimeter) and one does not.
2. Explore- Students will try to identify which compounds, from a list of ten, are electrolytes and which are
not based on a general definition.
3. Explain- Students will finish reading chapter 15.2 and take notes to compare weak electrolytes, strong
electrolytes, and nonelectrolytes (with pictures).
4. Elaborate- Students will answer a few multiple choice questions for practice with electrolytes then view
and explain the pickle electrocution.
Summary: Water is an excellent solvent for ionic compounds because it separates the ions and spreads them out
creating a homogenous aqueous solution. These types of solutions have a third colligative property- they conduct
electricity and so are called electrolytes.
Day 6: Ice Cream Lab
Objectives (SWBAT):
Physical Science 18- Given the concentration of a solution, calculate the predicted change in its boiling and freezing
point
Physical Science 20- Express concentration in terms of molality
Inquiry 5- Use mathematics to solve problems
Evaluated by:
Ice Cream Lab
Class structure:
Do Now: Which of the following is an electrolyte: NF3, CCl4, or MgO?
1. Engage- Class will review all three colligative properties and the effect of bond type and molality on the
properties of the solution.
2. Explore- Students will pair with another student to make ice cream using colligative properties.
3. Explain- Students will calculate the expected freezing point of the brine solution then compare their
measured value to the expected value and explain the difference.
4. Elaborate- Students will complete the test review for further practice (due Day 7).
Summary: Solutions have different properties than the solvent. These are called colligative properties (lower freezing
point, higher boiling point, conductivity) and testing them can be fun!
Day 7: Review for Solutions Test
Objectives (SWBAT):
Physical Science 14- Identify unknowns as solutions, colloids, or suspensions based on physical properties
Physical Science 18- Given the concentration of a solution, calculate the predicted change in its boiling and freezing
point
Physical Science 19- Predict the conductivity of a solution
Physical Science 20- Express concentration in terms of molality, molality, and percentages
Inquiry 5- Use mathematics to solve problems
Evaluated by:
Review for Solutions Test
Class structure:
Do Now: Organize your binder for tomorrow’s check.
1.
2.
3.
4.
Engage- Teacher will review the list of study topics on the board with student suggestions.
Explore- Teacher will discuss the answers to the test review.
Explain- Teacher will show all work during the discussion of the review questions.
Elaborate- Teacher will also review vocabulary and test layout.
Summary: Solutions are homogeneous mixtures of a solid or gas solute in a liquid solvent. The concentration of this
solution can be calculated as molality or molarity but the concentration changes the properties of the solvent (boiling
point elevation, freezing point depression, and conductivity).
Day 8: Solutions Test
Objectives (SWBAT):
Demonstrate at least 67% proficiency on the standards of this unit.
Evaluated by:
Test- Solutions
Class structure:
Do Now: Take out a calculator and something to write with, open your binder to the table of contents and place
it on the back bench, move your bags to the A/C, and clear your calculator RAM
TEST
Summary: The next unit, our last unit, builds on this one so if there is something you do not understand, you should
come in ASAP.
Testing Preparation
GLE
Objective
Day(s) Addressed
Inquiry 5
Utilize mathematics to solve problems
1, 2, 3, 4, 6, 7
Physical
Science 14
Identify unknowns as solutions, colloids, or suspensions based on physical
properties
1, 7
Physical
Science 18
Given the concentration of a solution, calculate the predicted change in its boiling
and freezing point
4, 6, 7
Physical
Science 19
Predict the conductivity of a solution
5, 7
Physical
Science 20
Express concentration in terms of molality, molality, and percentages
1, 2, 3, 4, 6, 7
Vocabulary
Solution
Suspension
Colloid
Concentrated
Dilute
Molality
Molarity
Colligative
Property
Weak Electrolyte
Equations
%= mass of solute/mass of solution
%= volume of solute/volume of solution
m= mol/kg
M=mol/L
Assessment Design
Basic: 6 Questions
Strong Electrolyte
Nonelectrolyte
M1V1=M2V2
ΔTb=m*i*kb
ΔTb=m*i*kf
Standard: 12 Questions
Expanded: 6 Questions
Essential Skills and Learning Objectives
Type of
Question
(MC, CR, P)
Basic
(Remember &
Understand)
Standard
(Apply &
Analyze)
Expanded
(Evaluate &
Create)
Identify unknowns as solutions, colloids, or suspensions
based on physical properties
Given the concentration of a solution, calculate the
predicted change in its boiling and freezing point
MC
1 MC
1 MC
CR
2 CR
1 MC
2 CR
2 CR
Predict the conductivity of a solution
MC/CR
1 CR
1 CR
Express concentration in terms of molality, molality, and
percentages
MC/CR
2 CR
1 MC
1 CR
4 MC
2 CR
3 CR