Due Date:
Name:
pH & Acidification lab Simulated
Date:
http://serc.carleton.edu/eslabs/carbon/lab7.html
Period:
Introduction
What is pH and what does it measure. It measure the concentration of H+ ions (protons floating around) in a solution. This is known as
acidity. The higher the concentration of protons, the lower the pH, and the more acidic the solution is. The lower the concentration of
protons, the higher the pH, and the more basic the solution is.
Have you ever wondered why the “p” in “pH” is a lower-case letter while the “H” is capitalized? What does it mean? The “p” stands for
potential and the “H” stands for Hydrogen. Okay, so that makes it as clear as mud. What is potential Hydrogen? A scientific
explanation would state that pH refers to the plant’s ability to attract hydrogen ions. A less scientific explanation says pH is the
acid/alkaline balance.
pH level refers to the amount of acid and alkaline contained inside of both the water and the growing medium or soil. If the environment
is too acidic, that means the plant will not attract enough hydrogen, while an environment that is too alkaline will attract too much
hydrogen. An environment that continually fluctuates from one extreme on the pH scale to the other is unhealthy for the plant.
The level of pH is measured on a scale of 0 to 14 with 0 representing the highest concentration of acid and 14 representatives of the most
alkaline or base. Seven is the magic figure for pH because it means that there is a balance of acid and alkaline in the solution and is often
referred to as pH neutral. The pH range of (0-6) are acidic, (7) is neutral, and (8-14) are basic or more alkaline.
Ocean Acidification
The oceans are naturally alkaline, or basic, with a pH of about 8.2. When carbon dioxide dissolves in sea water it forms carbonic acid (H 2CO3), which
releases hydrogen ions (H+), lowering the pH and making it more acidic. Scientists estimate that the additional carbon dioxide in the atmosphere and the
subsequent absorption of some of this by the oceans has lowered oceanic pH down to about 7.7. Although this is still slightly basic the end results is that
the ocean is slowly becoming more acidic. Lower oceanic pH range can have a harmful effect on the growth of energy and food producing
phytoplankton, species survival, skeletal and organ development and repair, homeostasis balance of essential nutrients, transfer and exchange energy
sources, and depth level pressure, sound, oxygen, and temperature ranges.
Oceans currently behave as carbon sinks because they absorb approximately 25-30% of the carbon dioxide put into the atmosphere by human
activities. Oceanographers and marine biologists are now seeing a relationship between changes in ocean pH and carbon dioxide dissolved in sea water.
Ocean acidity, as measured by pH, has increased by 30% since the industrial revolution and scientists predict pH will continue to change as increasing
amounts of carbon dioxide are absorbed by oceans. The chemistry of the oceans is important to life. Subtle changes in that chemistry may have
significant effects on the health of select ocean species that could lead to a global effect that impacts the earth’s entire ecosystem.
Materials
white vinegar, tap water,
pH scale chart, Spoon,
white chalk,
salt water,
Marker,
bottled water,
lemon juice, Paper towels, Spiral note book
soap,
*pH test strip,
medicine dropper, clear cups
*masking tape,
flexi Straws
*sea shells or egg shells (these are abundant, calcified shells and serve as a proxy for marine shells)
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Procedures
Step one: Read the lab introduction.
Step two: Number, the ph scale beginning with the number zero.
Step three: Identify the different sections of the pH scale as acid, base, and neutral.
Step four: Color code the pH scale range with dark (strongest) to light (weakest) shades of red and blue.
Step five: Locate the average ocean pH range from the lab introduction and label the name and range on the pH scale.
Step six: Record your predicted pH ranges for the listed samples on the data chart
Step seven: Place the pH strip into teacher prepared samples and record the observed pH measurements and reactions for all samples on the data chart
Step eight: Complete the questions below.
Step Nine: Construct and color the bar graph
Step ten: Complete the summary reflection
Neutral
Data chart measurements
Samples
pH predictions
Number / Acid,
Base
1
Bottled Water
2
Bottled water & Air
bubbles (CO2)
Observed pH
Neutral,
Number / Acid,
Base
Neutral,
Chalk
Predicted
reaction
Chalk
Dissolved
Yes No
Shell
Predicted
reaction
Shell
Dissolved
Yes No
3
Tap Water
4
Salt water
5
Soapy Water
6
Vinegar water
Name three possible variables that can affect the outcome of the results.
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Due Date:
Name:
Ocean Acidification Simulated lab
Date:
Period:
*Directions: Construct a bar graph that illustrates the ph range of the data samples listed on the x- axis of the graph below.
Color code the bars according to the matching pH chart range and record inside the bars if the samples are either an acid or base.
Ocean Water Simulated Acidification Data Results
p
H
14
13
12
M
e
a
s
u
r
e
m
e
n
t
s
11
10
9
8
7
6
5
4
3
2
1
0
Bottled water
Tap water
Bottled water & air bubble
Salt water
Soapy water
Vinegar water
Data samples
3
Lab summary reflection
*Directions: Begin the sentence with a sentence starter such as According to the introduction and data results……. Summarize the
answers to the questions below in a complete paragraph. Do not forget to check for errors. Spelling, punctuation, grammar, and sentence
structure and incorrect response will result in deduction points. Referring to the pH scale identify the ranges and classification. What is
the average ocean’s pH range? What can you infer if a given pH range is (1-6), (7), (8-14)? What effect does CO2 have on the ocean
ecosystem? What effect will this have on humans? What is the pH range for fresh water? Why is the ocean important? What does the air
bubbles represent? What are some variables that could influence the outcome of the lab results?
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