Name: ___________________________________________________ Period:__________________________
TITLE: Regulating pH
DAY 1
1.
Day 1
Stamp
YOUR GROUP’S ASSIGNED SOLUTION: __________________________________
2. TESTABLE QUESTION/PURPOSE: Read “On a Scale of 0-14” on p182. After reading write the purpose and testable question of this
lab.
Purpose:___________________________________________________________________________________________________
Testable Question:___________________________________________________________________________________________
3. BACKGROUND : Read the top of p183 & the Need to Know Box and answer the following questions:
1. In your own words what is a homogenate? _____________________________________________________________________
2. If you compared 2 solutions, 1 with a pH of 6 and another with a pH of 5, what would be the difference?
___________________________________________________________________________________________________________
3. How can minor imbalances in pH affect the outside and inside of your body?
___________________________________________________________________________________________________________
___________________________________________________________________________________________________________
Read the Need to Know Box on p188 and answer the following questions:
4. Why is it important to maintain proper pH in your body?
____________________________________________________________________________________________________________
5. What is a buffer? ___________________________________________________________________________________________
6. How do your cells maintain their pH? ___________________________________________________________________________
____________________________________________________________________________________________________________
4. MATERIALS LIST: Circle the materials that you need for your group’s assigned solution.
Assigned Solution
Liver + Acid
Liver + Base
Potato + Acid
Potato + Base
Water + Acid
Water + Base
Materials
pH probe, liver homogenate, dropping bottle of HCl, beaker with distilled water, graph paper
pH probe, liver homogenate, dropping bottle of NaOH, beaker with distilled water, graph paper
pH probe, potato homogenate, dropping bottle of HCl, beaker with distilled water, graph paper
pH probe, potato homogenate, dropping bottle of NaOH, beaker with distilled water, graph paper
pH probe, beaker with distilled water, graph paper, dropping bottle of HCl
pH probe, beaker with distilled water, graph paper, dropping bottle of NaCl
5. PROCEDURE:
1. Gather all materials and bring them to your desk.
2. Turn on the pH probe and gently swirl it in the beaker of distilled water until it reaches a pH of 7.
3. Place the pH probe in your assigned solution. Wait until the pH stabilizes (stops changing) and record the initial pH in your data
table under the column labeled 0 drops.
4. Add either HCl (acid) or NaOH (base) depending on your assigned solution 1 drop at a time until you have added 5 drops. Gently
swirl the mixture after each drop.
5. Using the pH probe determine the pH of the solution. Record this in your data table.
6. Repeat steps 4 & 5. Record the pH after every additional 5 drops until you have added a total of 30 drops.
7. Discard the homogenate mixture and rinse the pH probe and beaker thoroughly. Return all materials to the location designated by
your teacher.
6. Independent variable: identify the cause or the thing you are changing in this experiment
______________________________
7. Dependent variable: identify the effect or the thing you are measuring in this experiment
_______________________________
8. Constants: identify the things you are not changing in this experiment
_________________________________________________
9. Hypothesis: Write your hypothesis based on the procedure above and your assigned solution………
If _________________________________________________________________________________________________________,
then _______________________________________________________________________________________________________,
because_____________________________________________________________________________________________________
Day 2
Stamp
DAY 2
10. RESULTS: Record your and the class results in the data table below.
Assigned
Solution
pH after addition of drops
0
5
10
15
20
25
30
Liver + acid
Liver + base
Potato +
acid
Potato +
base
Water +
acid
Water +
base
11. GRAPH: On graph paper draw a full size graph similar to the one in fig 5.9 on p186. Use the data from the table above to make a
line graph that shows 6 separate lines, one for each solution. Your graph will need to include a legend similar to the one in fig 5.9 so
you know what solution each line represents. Code your 6 lines using color or different line types.
12. DATA ANALYSIS: Answer the following questions:
8. (p187) ____________________________________________________________________________________________________
____________________________________________________________________________________________________________
10. (p188)
a.__________________________________________________________________________________________________________
____________________________________________________________________________________________________________
b.__________________________________________________________________________________________________________
____________________________________________________________________________________________________________
c.___________________________________________________________________________________________________________
____________________________________________________________________________________________________________
Analysis p188:
1. __________________________________________________________________________________________________________
2. __________________________________________________________________________________________________________
13.CONCLUSION:
Directions: Type your conclusion using the following MELCon outline and attach it to the back of this handout. Use 12 pt times new
roman font double spaced.
Paragraph 1 (ME)
 M - Restate the purpose, testable question, hypothesis and whether your hypothesis was supported by the data.
 E- You must use at least 2-3 pieces of evidence from the data table, graph, or data analysis that supports your hypothesis.
This means you must use numbers!
Paragraph 2 (L)
 L – Using what you learned in part 3 Background & part 12 Data Analysis develop possible explanations for why the results
turned out the way they did. Include the vocabulary words pH, buffer, homogenate in your explanation.
Paragraph 3 (CON)
 Suggest at least 2-3 ways/methods to improve this investigation to get more accurate results.
 Why is this project important and what implications/impact does this have or could have on others.
Name: ______________________________________________________
Period:_________________________
Regulating pH Lab Scoring Sheet
Section
Day 1
Points Possible
10
Day 2
10
Conclusion
10
Points Earned
Comments
Complete & on time = 10 points
Incomplete and/or late = 5 points
Missing = 0 points
Conclusion will be scored using the rubric below:
Mastery
Proficient
10-9 points
8-7 points
Conclusion lacks a clear
Conclusion Conclusion clearly refers to
the question and purpose
reference to one of the
and states whether or not
following: the question,
the data supports the
purpose, or hypothesis.
hypothesis. Hypothesis is
restated.
Needs Improvement
6-5 points
Conclusion lacks a clear
reference to 2 of the
following: the question,
purpose, or hypothesis.
Unsatisfactory
4-3-2-1-0 points
Conclusion lacks
reference to the
question, purpose,
and hypothesis.
Hypothesis is clearly and fully
supported by at least 3
pieces of evidence (numbers)
referenced from the data.
Hypothesis is clearly and fully
supported by at least 2 pieces
of evidence (numbers)
referenced from the data.
Hypothesis is clearly and
fully supported by at least 1
piece of evidence
(numbers) referenced from
the data.
Hypothesis is not
supported by
evidence referenced
in the data.
Clearly explains at least 3
possible reasons why the
data turned out the way it
did using vocabulary
Clearly explains at least 2
possible reasons why the data
turned out the way it did
using vocabulary
Briefly mentions one reason
why the data turned out the
way it did.
Does not attempt to
explain why the data
turned out the way it
did.
At least 3 possible errors that
may have affected your
results and at least 3 changes
to the experiment are clearly
explained.
At least 2 possible errors that
may have affected your
results and at least 2 changes
to the experiment are clearly
explained.
One possible error that may
have affected your results
and one change to the
experiment are explained.
No possible errors or
changes are discussed.
Importance of project and
implication on others is
clearly and fully discussed.
Importance of project and
implication on others is clearly
discussed but brief.
Importance of project and
implication on others is
brief and not clearly
discussed.
Importance and
implication of project
is not discussed.