LESSON PLAN
Name: Johanna Villalon
Title
of lesson: Acids and Basis
Date
of lesson: 5th six weeks
Length
of lesson: 1 hour
Description
of the class:
Name
of course: Chemistry
Grade
level: 9th
Honors
or regular: Regular
Source
of the lesson:
http://www.google.com/search?hl=en&lr=&oi=defmore&q=define:ACID+RAIN
http://www.policyalmanac.org/environment/archive/acid_rain.shtml
TEKS
addressed:
(1) Scientific
processes. The student, for at least 40% of instructional time, conducts field
and laboratory investigations using safe, environmentally appropriate, and
ethical practices. The student is expected to:
(A) demonstrate safe practices during field and laboratory
investigations; and
(B) make wise choices in the use and conservation of resources
and the disposal or recycling of materials.
(2) Scientific
processes. The student uses scientific methods during field and laboratory
investigations. The student is expected to:
B) collect data and make measurements with precision;
(D) organize, analyze, evaluate, make inferences, and predict
trends from data; and
(E) communicate valid conclusions.
(14) Science
concepts. The student knows the properties and behavior of acids and bases. The
student is expected to:
(A) analyze and measure common household products using a
variety of indicators to classify the products as acids or bases;
(D) describe effects of acids and bases on an ecological system.
I. I.
Overview
Students will be
able to distinguish the differences between acids and basis. They will
investigate how the difference in concentrations of hydrogen and hydroxide ions
determine the acidity or alkalinity of solutions by presenting a graphical
representation and the appropriate equation that describes their experimental
data. This lesson should be taught before the benchmark lesson about pH.
II. Performance or learner outcomes
Students will be able to:
·
Formulate an
experimental unit to measure the concentrations of ions
·
Collect data
from their experiment
·
Analyze the data
and graph any relationships to see how pH depends on the concentrations of ions
·
Interpret graph
to formulate an equation that fits the data
·
Relate pH units
with everyday items such as acid rain or cleaning products
III.
Resources, materials and supplies needed
Engagement: 5 packs of starburst both
regular and sour.
Exploration: 1L of 0.1M HCl, 0.1M NaOH, and
DI water
Per group:
2 600ml beakers
filled with 350 ml of DI water
1 250ml beaker
filled with 0.1M HCl
1 250ml beaker
filled with 0.1M NaOH
2 Plastic Pipettes
pH
probe
goggles
gloves
IV.
Supplementary materials, handouts.
Instructions for Exploration
Five-E Organization
Teacher
Does Probing Questions Student
Does
|
Engage: Learning Experience(s) Have a bowl of
starburst (one of each flavor) in front of the class. Then distribute
starburst around for students to be able to eat and categorize based on
taste. Explain to students that
in chemical solutions, one can categorize the amount of sourness (or acidity)
with units of sourness = hydrogen concentration; chemical solutions can also
be categorized with units of sweetness or alkalinity with units of sweetness
= hydroxide concentration. The range of acidity or basicity is called pH. |
Critical questions that
will establish prior knowledge and create a need to know How can we qualify the
differences between tastes? How can we quantify the
differences between tastes? What would our scale of
sweetness and sourness be for the taste of starburst. |
Expected Student Responses/Misconceptions Students should be able to
arrange starburst in order of sweeter to bitter. They can implement units
of sweetness and units of sourness to each starburst and create a scale. |
|
Explore: Learning Experience(s) Break students in groups
of no more than 3. Each groups should have 2
beakers filled with DI water, a beaker with diluted (0.1 M) HCl, a beaker
with diluted (0.1 M) NaOH, 2 plastic
pipettes, a pH probe, goggles (enforce students to wear goggles at all times,
otherwise, they will be dismissed from experiment), and gloves. Instructions:
|
Critical questions that
will allow you to decide whether students understand or are able to carry out
the assigned task (formative) Is
hydrochloric acid a strong acid or weak acid? How about NaOH? How
do you know is a weak or a strong acid? What
happens to these chemicals when you throw them in water? What is the chemical
formula for water? Does water have
concentrations of H+ and |
Expected Student Responses/Misconceptions HCl
and NaOH are both a strong acid and a strong base, respectively. They
are strong acids and basis because they ionize completely in water and
therefore affect the concentrations of hydrogen and hydroxide ions in
solutions. The
chemical formula for water is H2O. Pure
water has equal amounts of H+
and |
|
Explain: Learning Experience(s) Have 3 groups of
students come up and draw their graphs on the board. Have each group explain
the graph to the class commenting on the units used,
the labels for the axis, and the relationship of the grap. |
Critical questions that
will allow you to help students clarify their understanding and introduce
information related to concepts to be learned Which pH values represent
acids and basis and why do you think so? What do you think is
happening in the water as soon as you add the acid or base? Is pH a value that depends
on a variable? If so, what is that variable? What is the pH scale or
range for this experiment? How come water has a
neutral pH? Based on the graphs, what
kind of relationship can we see between concentration and pH? Is there any
linear relationship? How can we come up with an
equation that represents the graphs? What is a logarithm? Could we have used other
solutions as our hydrogen or hydroxide ions? If so, which ones? What
if we mix both that acid and base in the same beaker? Can
we be safe to pour the acid mixed in the water to the sink. |
Expected Student Responses/Misconceptions Low
pH values represent acids and high pH values represent bases As
soon as the acid or base is added to water, it splits and ionizes because
they are strong acids and bases. pH depends on the concentration of hydrogen or hydroxide
ions in solution. The pH scale is from 1 to
14 but student may not be able to reach all the way to 1 or 14 Because the amounts of
both ions are the same so they cancel each other out. There is no linear relationship, it follows a curved relationship that
closely resembles the path of a logarithm. The pH equation is equal
to the negative logarithm of the concentration of hydrogen ions. A logarithm is the
representation of what would happen if we double the concentration of
something 10X so every number represents at fold of 10x
either 10x more dilute or 10x more concentrated. We could have used other
strong acids or bases to generate the ions and calculate pH changes based on
their concentrations. We could have used sulfuric acid which is a strong acid,
or KOH Since they have the same
molarity, they should provide a neutral pH. Yes because it is
neutralized by water as long as you keep water running while pouring the diluted acid! |
|
Extend / Elaborate: Learning Experience(s) Ask
students the following questions: What is acid rain? How does it form? What is the impact in our
society? Can you think of any foods
that are acidic? What household items are
basic? |
Critical questions that
will allow you to decide whether students can extend conceptual connections
in new situations |
Expected Student Responses/Misconceptions Also called acid precipitation or acid deposition, acid rain is precipitation containing harmful amounts of nitric and sulfuric acids formed primarily by nitrogen oxides and sulfur oxides released into the atmosphere when fossil fuels are burned. It can be wet precipitation (rain, snow, or fog) or dry precipitation (absorbed gaseous and particulate matter, aerosol particles or dust). Acid rain has a pH below 5.6. Normal rain has a pH of about 5.6, which is slightly acidic. Acid rain causes acidification of lakes and streams and contributes to damage of trees at high elevations (for example, red spruce trees above 2,000 feet) and many sensitive forest soils. In addition, acid rain accelerates the decay of building materials and paints, including irreplaceable buildings, statues, and sculptures that are part of our nation's cultural heritage. Prior to falling to the earth, SO2 and NOx gases and their particulate matter derivatives, sulfates and nitrates, contribute to visibility degradation and harm public health. Soap, cleaning
preparations, Baking soda. |
|
Evaluate: Lesson Objective(s) Learned (WRAP ≠UP
at end) -> Summarize Ask
students as a group What is the difference
between an acidic solution and a basic solution? How do we measure their
difference? What is the pH range? What does pH depend on? What kind of relationship
does pH and concentration have? Name an example of a
product that is acid and one that is basic. |
Critical questions that
will allow you to decide whether students understood main lesson objectives |
Expected Student Responses/Misconceptions An
acidic solution contains more hydrogen ions than hydroxide ions. A basic
solution contains more hydroxide ions than basic ions. We
measure their differences with pH units. pH
range: 1-14 pH
depends on hydroxide or hydrogen ions concentrations A
logarithmic relationship Look
at answers above. |
INSTRUCTIONS FOR ACTIVITY
1. Calculate the number of moles of HCl
and NaOH contained in their beakers.
2. Measure the pH of DI water.
3. You will be adding amounts of acid
or base to each beaker containing DI water. Determine the amount of liquid that
you would add in which you will be calling it the unit of acidity or unit of
alkalinity. How many moles of hydrogen or hydroxide concentration does your
unit of measurement contain?
4. Add equal amounts of units of
acidity or basicity to the DI water in different beakers and record the pH.
(Add up to 6 units of acid or base)
5. Compile the data obtained in a
graph. Which is your independent variable? Independent variables are graphed in
the x-axis.
6. What is the range in your
measurements? Lowest value and Highest value.