Dissolving Rate Inquiry Lesson
For more great info, go to
http://www.alka-seltzer.com/as/experiment/student_experiment.htm.
There are a variety of student experiments lined out there. I wanted
to do the Alka-Rockets
Background
There are many different factors that affect the dissolving rate of a substance. Some of
the factors that make a difference in the dissolving rate of a substance are the concentration of
the liquid, any movement that is added, the temperature, surface area of the solute, the kind of
matter being dissolved, and the mass or volume of the substance.
Students will learn about each of these factors through investigations and inquiry. The
teacher must have extensive background knowledge of the factors of dissolving so that they can
assist students in their experiments and answer questions that may be addressed. The teacher
should already understand the following facts, and the students will learn these through their
experiments. This lesson follows the following Oklahoma PASS content standard and objective:
PHYSICAL SCIENCE
Grade 5
Standard 1: Properties of Matter and Energy - Describe characteristics of objects based on
physical qualities such as size, shape, color, mass, temperature, and texture. Energy can produce
changes in properties of objects such as changes in temperature. The student will engage in
investigations that integrate the process standards and lead to the discovery of the following
objectives:
1. Matter has physical properties that can be used for identification (e.g., color, texture, shape).
First, concentration of the solvent will affect the rate at which the solute dissolves. As
the concentration of the liquid doubles, the dissolving rate doubles as well. This means that the
more concentrated the solvent, the faster the solute will dissolve.
1
Dissolving Rate Inquiry Lesson
Second, any movement added to the experiment will assist the dissolving rate of the
substance. Both stirring and shaking accelerate the dissolving process. When movement is
added, the surface area of the substance increases as it is broken down into smaller pieces. Also,
there is more contact between the solute and the solvent. Movement creates kinetic energy
which raises the temperature as well as the dissolving rate.
Third, temperature can affect the dissolving rate of matter. An increase in temperature
will increase the dissolving rate of the substance. It causes the molecules to move more rapidly
which increases the kinetic energy. This allows the solute to break down even more, and the
molecules come into contact with more of the solute molecules. When the temperature is
lowered, the molecules move more slowly and create less energy. This means that the molecules
come into contact with fewer solute molecules and do not dissolve as quickly.
Fourth, the size of the surface area will influence the dissolving rate. The larger the
surface area, the more solvent can touch the substance and increase dissolving. If the surface
area is smaller, not as much solvent can touch the substance, which decreases the dissolving rate.
Fifth, the matter being dissolved will affect the dissolving rate. Some matter is
impossible to dissolve and therefore is insoluble. Some substances naturally dissolve more
quickly than others. An example of this is that sugar will dissolve more quickly than a stone.
Finally, the mass or volume of the substance has an effect on the dissolving rate. The
larger the mass of an object, the more time it will take to dissolve. Or if there is less volume of
liquid to place the object in, the dissolving rate will also slow down.
While the students perform the various experiments in the lesson, they will practice a few
process skills from the Oklahoma PASS objectives such as observe and measure, classify,
experiment, interpret and communicate, and use inquiry tools.
2
Dissolving Rate Inquiry Lesson
SCIENCE PROCESSES AND INQUIRY
Grade 5
Process Standard 1: Observe and Measure - Observing is the first action taken by the learner to
acquire new information about an object, organism, or event. Opportunities for observation are
developed through the use of a variety of scientific tools. Measurement allows observations to be
quantified. The student will accomplish these objectives to meet this process standard.
2. Compare and/or contrast similar and/or different characteristics (e.g., color, shape, size,
texture, sound, position, change) in a given set of objects, organisms, or events.
Process Standard 2: Classify - Classifying establishes order. Objects, organisms, and events are
classified based on similarities, differences, and interrelationships. The student will accomplish
these objectives to meet this process standard.
2. Arrange objects, organisms, and/or events in serial order (e.g., least to greatest, fastest to
slowest).
Process Standard 3: Experiment - Experimenting is a method of discovering information. It
requires making observations and measurements to test ideas. The student will accomplish these
objectives to meet this process standard.
1. Ask questions about the world and formulate an orderly plan to investigate a question.
2. Evaluate the design of a scientific investigation.
Process Standard 4: Interpret and Communicate - Interpreting is the process of recognizing
patterns in collected data by making inferences, predictions, or conclusions. Communicating is
the process of describing, recording, and reporting experimental procedures and results to others.
Communication may be oral, written, or mathematical and includes organizing ideas, using
3
Dissolving Rate Inquiry Lesson
appropriate vocabulary, graphs, other visual representations, and mathematical equations. The
student will accomplish these objectives to meet this process standard.
1. Report data using tables, line, bar, trend, and/or simple circle graphs.
3. Make predictions based on patterns in experimental data.
4. Communicate the results of investigations and/or give explanations based on data.
Process Standard 5: Inquiry - Inquiry can be defined as the skills necessary to carry out the
process of scientific or systemic thinking. In order for inquiry to occur, students must have the
opportunity to ask a question, formulate a procedure, and observe phenomena. The student will
accomplish these objectives to meet this process standard.
1. Use different ways to investigate questions and evaluate the fairness of the test.
2. Use a variety of measurement tools and technology.
3. Formulate a general statement to represent the data.
4. Share results of an investigation in sufficient detail so that data may be combined with data
from other students and analyzed further.
Students will “observe and measure” by looking at a variety of characteristics of
dissolving alka-seltzer tablets and decide which ones affect the substance more than others.
They will “classify” by taking the traits that they have observed, and put them in different orders,
such as most powerful to least powerful. They will “experiment” by asking questions to predict
which of the concepts has the most affect on the dissolving rate, followed by evaluating their
thoughts when they are finished with the experiments. They will “interpret and communicate”
by making a final graph of their findings to share with the class and be able to predict how the
factors that they test will affect other substances. Students will use “inquiry” by learning through
4
Dissolving Rate Inquiry Lesson
experimentation what factors affect the dissolving rate of alka-seltzer and which do not have any
affect. They will pose questions in their mind, and answer these through their findings.
5
Dissolving Rate Inquiry Lesson
6
Dissolving Rate Inquiry Lesson
Lesson Plan
2. (a) List several objectives you have for students (both process and content).
*The student will be able to understand the concepts concerning dissolving rate.
*The student will be able to identify the variables that affect the dissolving rate.
(mass/volume of substance, concentration, movement, temperature, surface area,
matter being dissolved)
*The student will be able to identify that the rate of a chemical reaction is affected by the
physical size of the reactants.
*The student will be able to predict which concept has the most affect on the dissolving
rate.
*The student will be able to construct a graph using their observations and measurements
through out the investigation.
*The student will be able to define concentration.
*The student will be able to define dissolve.
*The student will be able to define solute.
*The student will be able to define solvent.
*The student will be able to define surface area.
*The student will be able to define kinetic energy.
7
Dissolving Rate Inquiry Lesson
*The student will be able to define matter.
*The student will be able to define molecule.
*The student will be able to define mass.
*The student will be able to define volume.
*The student will be able to define reactant.
*The student will be able to demonstrate that the rate of a chemical reaction can be
increased by increasing the temperature of reactants.
*The student will be able to observe the factors that affect the dissolving rate.
*The student will be able to measure which factor most affects the dissolving rate.
*The student will be able to classify their observations in order from most powerful to
least powerful affect on the dissolving rate.
*The student will be able to interpret their constructed graph and communicate their
discoveries to their peers.
*The student will be able to name all 6 of the given factors that affect the dissolving rate.
*The student will be able to determine that increased surface area increases the rate of
dissolving.
*The student will be able to determine that the dissolving rate is disturbed by movement.
*The student will be able to determine that the dissolving rate is changed by temperature.
8
Dissolving Rate Inquiry Lesson
*The student will be able to determine that the dissolving rate is affected by surface area.
*The student will be able to determine that the dissolving rate is altered by the matter
being resolved.
*The student will be able to determine that the dissolving rate is influenced by the mass
or volume of the substance.
2. (b) What questions might students have about the concept(s)? What questions could you
ask students during the course of the lesson?
Student Questions:
1. Does the temperature of the water affect the dissolving rate?
2. Does the surface are of the water affect the dissolving rate?
4. Does the concentration of solvents affect the dissolving rate?
5. Are dissolving rate and reaction rate the same?
6. Why do different factors affect the dissolving rate differently?
7. Which variable will affect the reaction rate the most?
8. Which factor will affect the reaction rate the least?
9. Will mixing these chemicals together cause an explosion?
10. Why do we need to understand the characteristics of a dissolving rate?
Teacher Questions:
9
Dissolving Rate Inquiry Lesson
1. In 8 ounces of water, how long would it take 1 alka seltzer tablet to melt?
2. What would happen to the reaction rate if the temperature is doubled?
3. What would happen to the reaction rate if you used hot tap water?
4. What happens to the surface area as the particle size decreases?
5. Does particle size or temperature have more of an affect on the rate of reaction?
6. What occurs when the concentration of the reactants decreases?
7. Does stirring have any affect on the rate of reaction if the reacting substances are
already in the solution?
8. What happens when two substances react together?
9. Define the terms solute, solvent, concentration, and reactant.
10. Classify from most powerful to least powerful the effectiveness of each
variable investigated on the dissolving or reaction rate.
11. Interpret and demonstrate the graph you constructed to your classmates during a
class discussion about your investigation discoveries.
12. Compare and contrast the effects of the mass/volume of a substance, concentration,
movement, temperature, surface area, and matter being dissolved on the dissolving or
reaction rate.
13. Construct a graph using one component that affects the dissolving rate and a time
component.
10
Dissolving Rate Inquiry Lesson
14. Predict which of the factors to be investigated will have the most affect on the
dissolving rate.
15. Describe the characteristics of a solute.
16. Identify the solvent used in each investigation.
2. (c) What is the teacher’s role during the lesson?
The teacher acts as the facilitator during these investigations. The teacher will challenge
the students to further experiment by questioning their processes and asking questions to guide
them through their investigation. Many students may at times feel “stuck.” The teacher may use
these opportunities to ask preplanned questions to advance the focus of their exploration. The
teacher’s role is to pose the central question of the investigation which is “What affects the
dissolving rate?” The teacher’s questioning helps students stay interested in the investigation.
The teacher will use questions, discussions, and assigned tasks to evaluate the students progress
during the investigation and their full understanding at the conclusion of the investigation.
During the explain phase, the teacher plays a more active role than in the explore phase. The
teacher does not give away answers or directly answer questions but returns questions with
questions. During this phase, the teacher takes the opportunity to make sure the students have an
understanding of the concept at hand. During the expand phase, the teacher’s role is to bring up
realistic connections between the investigation and a real life situation. An example would be:
with the alka seltzer investigation, the student will not only have a process understanding of
“dissolving rate” but will also have an understanding of how the medicine “alka seltzer” helps
people feel better. The teacher also uses the opportunity to make sure the 3 H’s are being
addressed, that the head, heart, and hands are being attended to. While evaluating through out the
11
Dissolving Rate Inquiry Lesson
investigation, the teacher’s role includes testing the given concepts outside of the typical
confines of the assignment, question, and identify any misconceptions.
2. (d) What data will be collected by students and how will it be collected?
The students will collect data through out the divisions of the investigation. The students
will time dissolving rates, chart temperatures, administer and observe the affects of movement,
measure particle size, surface area, concentration, and mass and volume of a given substance.
2. (e) How will the data be used/represented by students?
The students will use the data collected to construct a graph with multiple components.
The students will use the graph to deepen their understanding of dissolving rates. They will also
use the graph to share and discuss their findings with their classmates. The graphs will also be
used as a form of evaluation for the teacher to make sure they understand the concepts and that
there are not misconceptions.
The 4-E Learning Cycle:
EXPLORE
During the explore phase, the students will perform 4 experiments that will each add to their
understanding of dissolving rate. Each investigation will be centered around the use of alka
seltzer. The questions for each investigation are as follows:
1. How does temperature affect the dissolving rate?
The idea: In order for a chemical reaction to occur, the particles, atoms or ions, which are
reactants, must physically come into contact with one another. Anything that increases the
12
Dissolving Rate Inquiry Lesson
frequency of these encounters will increase the rate at which the products are formed. The rate of
chemical reaction can be increased by increasing the temperature of these reactants.
2. How does particle size affect the dissolving rate?
The idea: The rate of a chemical reaction is affected by the physical size of the reactants.
Decreasing the size of the particles which make up a given weight will increase the number of
particles represented by the same weight. Smaller particle size results in an increase in the rate of
reaction because the surface area of the reactant has been increased.
3. How does concentration affect the reactants?
The idea: The rate of chemical reaction depends on the frequency of the collisions between
the atoms or ions of the reactants. As the concentrations of the reactants decreases, the frequency
of collisions decreases, and the rate of reactions slows down.
4. What factors affect the rate of chemical reactions?
The idea: If any of the products or reactants involved in a chemical reaction are gases, the rate
of reaction will decrease as pressure on the system is increased.
The purpose of this phase is to get students interested in the concept and motivated to ask their
own questions about the investigation or factors of it. The students are encouraged to think on
their own, and the experiments provide the student an opportunity to be introduced to the idea of
dissolving rates. In this phase, students will be testing their ideas and constructing knowledge
about a new concept.
EXPLAIN
13
Dissolving Rate Inquiry Lesson
During this phase the students will be asked to define concentration, dissolve, solute, solvent,
surface area, kinetic energy, matter, molecule, mass, volume, and reactant. These words will give
the students the necessary terminology to better understand the concept. The teacher at this point
will use the concept map to link all of the variables together in understanding the multiple
characteristics and variables of the dissolving rate. This phase will better explain the explore
phase, and at this point, the students will be “hooked” and more apt to give their attention to the
subject and understanding it better. During this phase, the students will compile data and
collaborate with their peers to discuss their findings. Hopefully, during this phase, the student
will being to see the concept as a whole, and not as multiple divisions of experiments.
EXPAND
During the expand phase there are multiple arenas to explore. One experiment teachers could add
is called “Alka Rockets”. In this experiment, the student will design a paper rocket propelled by
alka seltzer and water to demonstrate Newton’s Third Law of Motion. This experiment could be
tied into social studies by incorporating a unit on events in space. This experiment could be the
science component in a social studies unit, or an art component in a social studies unit. In the
lesson centered around dissolving rate, the teacher can incorporate math by simply adding
graphing as a component of the investigation, as we have done. To accommodate ELL students,
the teacher could create a matching game using index cards and the needed vocabulary terms to
help the students get more familiar with the terms which will lead to a better understanding of
the concept. Accommodating special needs students covers a very wide array of issues. Without
knowing the specific needs of the student, or having seen an I.E.P, we can only give broad
examples of accommodation. If the student has a physical constraint, the teacher could pair them
with a student whom they trust to help the special needs student by both performing the actual
14
Dissolving Rate Inquiry Lesson
tasks of investigation, but still including the student while discussing the concept or forming
opinions and understanding about the subject. If the student has a mental disability, they can also
be paired with a partner, but may be asked to participate in the investigation as mush as possible,
and may not be held accountable for questions that are at a generally high cognitive level.
Teachers may also consider finding web simulations or pre recorded simulations to allow the
special needs student to view in a quieter environment for better understanding. The expansion
phase is used to build on a given concept, use the concepts in a different way, and give students a
real world application of the concept.
EVALUATE
Evaluation will occur through out the investigation via the teacher asking multiple challenging
questions to encourage a deeper understanding of the concept. The teacher may also use the
graph(s) constructed during the investigations as evaluations to determine the level of
understanding of each student. And the teacher may also use class discussions to gage the
understanding of each student as well as each individual’s response to purposed questions
through out the investigation.
15