#1883. The pH scale

Science, level: Elementary
Posted Thu Aug 3 16:43:54 PDT 2000 by Kris Adler (BGFH@grove.iup.edu).
IUP, Indiana
Materials Required: Resources: Teacher's computer, power point presentation, digital projection
Activity Time: 50 minutes
Concepts Taught: pH scale. chemistry, acids, bases, litmus, neutral

Sample Lesson Plan

Sixth Grade Science: 50 mins

Topic: Acids and Bases

Resources: Teacher's computer, power point presentation, digital projection
unit, chemicals for teacher presentation, lemon juice, vinegar, soda, rainwater,
milk, pure water, egg whites, baking soda, ammonia, drano, pH paper, litmus
paper, beakers to hold substances, safety goggles.

Learners Characteristics

Demographic characteristics
There are 18 students in this class, and there are an equal amount of girls as
there are boys. All the students are either eleven of twelve years in age, with
the exception of one student who is ten. The students come from all over the
country. Only a few have been born and raised in this town. The school is
located in a suburban setting only 20 miles away from Las Vegas. The students
all live within a 15 minute drive of the school. All the students have
experienced different kinds of life styles. Some of the children have parents
who are farmers and they live on farms. Others have parents who are blue
collar workers and live in developments. And, yet other students have parents
who are white collar executives and live in larger homes on the outskirts of
town. The group of students has a diverse background.

Topic-Specific Characteristics
Since the class is such a diverse group all the students are at different levels in
there education. Most students have achieved an average intelligence, there
are a few who are a little bit faster, and a few who are a little bit slower than
the average. All the students in the class have received at least three years of
science education in their lives, but some have had more. The topic of this
lesson is something totally new. None of the students have gone over this, and
none of them have done labs in which they test the pH of household items to
see if they are acidic or basic. Since there is no prior knowledge on the
students part, everything is to be taught implicitly. In addition to never having
gone over acids and bases, this is the first time these students will be doing
anything that is chemistry related.

Rationale
This is one lesson in a unit of chemistry. It introduces students to the
concepts of acids and bases. Some key terms the students will be learning are
acids, bases, pH scale/value and litmus paper. They main point to this lesson is
learning what some acids and bases are. As well as learning what acids and
bases are, students will take part in a lab in which they will classify different
substances as acids or bases.

Objective
After completing the lesson on acids and bases, sixth grade students will be
able to correctly identify items as acids or bases by using a pH test 100% of the
time.

More specifically, the learners will be able to:

ü display appropriate behaviors when doing the labs.
ü list the common properties of acids and bases.
ü classify substances as acids or bases, by using pH and litmus tests.
ü explain the pH scale.

Activity/Lab

TIME TEACHERS ACTIVITIES LEARNERS' ACTIVITIES
5 mins The teacher will give a small presentation on chemical reactions to get the students interested in the lesson that follows. The presentation will be on titrations of acids and bases. After the teacher has given the presentation on chemicals, ask the class to come up with some explanations of what happened. Give them a few minutes to share their observations.
15 mins The teacher will introduce the term chemistry to the class. This is what their next unit in science will be on. After the introduction give a power point presentation on the terms and concepts they will need to know for this lesson. Some of these terms are acids, bases, pH, litmus, and the definition of chemistry. While the teacher is giving the power point presentation, the learners are expected to take notes on the terms and concepts. They will need to know this material for future lessons.
5 mins The students are being prepared to do their first lab experience, the teacher should caution the students of the safety rules in a lab atmosphere. The learners should also be informed of he guidelines and proper behaviors that should be displayed in a lab. The students are not required to take notes on these materials, but they will be observed by the teacher to see that they are displaying the appropriate behaviors. These rules and regulations will have to be followed for all of the upcoming labs as well.
20 mins The teacher gives the students the lab procedures that they are going to be using for this lab. After everyone has received instructions, the teacher will go over the directions step by step to insure that the students know what is going to be happening. The learners are going to be doing a lab on testing the pH of common substances to see if they are acids or bases. They will be using the pH test first to if the substance is an acidic or basis, and then they will be using litmus paper to confirm their first hypothesis.
5 mins This is where the teacher informs the learners that it is time to clean up. After every lab the students are expected to have the classroom as it was before the lab. The students will clean up the room and make it look the way it did before the lab started. After the learners have put the room back together, they are dismissed from class.

.

Evaluation
1. Each student is required to had in their results from the lab. They should have included which
substances they thought were acids, which were bases, and which were neutral.

2. Along with the results from the lab students should include two things they learned about acids and
bases from their lab.

Notes

Chemistry: This lesson comes from one unit that is on chemistry. Chemistry
is the science that deals with the composition and properties of substances.

This whole lesson is on the pH scale. It deals with substances that are acids,
bases, and those that are neutral.

The pH scale is a way of measuring the acidity of a substance whether it be a
base or an acid. The scale goes from one to fourteen. The smaller numbers are
acids, the larger ones are bases, and the ones right around 7 are neutral.

Acids are substances that are higher up on the pH scale. They run from 1 to 6.
One is the strongest acids, and six is the weakest. Another way to test
substances is with litmus paper, if they turn the paper red then they are acidic.
In addition to this acids are known for having a sour taste.

A caution, when working with substances in the lab, never stick
anything in your mouth. Do not taste the substance to see if they are sour or
bitter. Also when doing lab experiments with chemical, you should not stick
anything near your face. This includes smelling, tasting, and looking.

Bases are substances that are located lower down on the pH scale.
They run from 8 to 14. Eight is the weakest, and fourteen is the strongest acid
there is. To see if a substance is a base, a litmus test may be done. If the test
result are blue then the substance is a base. Bases feel soapy and slippery, and
in addition to this they have a bitter taste. Have you ever gotten soap in you
mouth? Soap is a base.

Neutral substances are those that fall right on the number seven on the pH
scale. There are not very many substances that are commonly found to be
neutral. The only one is pure water.

There is one more way to check the acidity of a substance and this its
through litmus paper. If the litmus paper turns red then the substance is an
acid, if it turns the paper blue then the substance is a base. The litmus test is a
way to just test for acids and bases. It does not test the strength such as the pH
does.

Here are some fun sites to visit if you want to learn more about chemistry and
acids and bases.

Additional labs to try: Chemistry comes in many different forms. This site
has an activity that has to do with crystals. The address is
http://www.iit.edu/~smile/ch8808.html

Books that teach chemistry: This site has all different kinds of books that do
fun and interesting things with chemistry books. This site is located at
http://chem.csusb.edu/~dpedersn/chem_elementary_educ.html

Fun activities for the whole family: At this site fun activities for children of
all ages can be found. All the chemistry experiments can be done at home, and
the materials needed are things that are around the house. These are fun
activities for a rainy day. The site is located at
http://personal.cfw.com/~rollinso/SciFood.html