The Potential of Crushed Crab Shells As pH Buffer

__________________

A Research ProposalPresented to the

Science & Mathematics DepartmentIntegrated Developmental SchoolMSU-Iligan Institute of Technology

__________________

In Partial Fulfillment for the CourseScience Research

__________________

Marx Caesar S. BarluadoMishari Rashid M. Lucman

APPROVAL SHEET

This research paper entitled “The Potential of Crushed Crab Shells As pH Buffer)” prepared and submitted by Marx Caesar S. Barluado and Mishari Rashid M. Lucman.

PROF. ODYSSA NATIVIDAD R. M. MOLOAdviser

__________________Date

PROF. ALMA GLORIA L. SILVA PROF. VERONICA C. SERATEPanel Member Panel Member

_________________ ________________ Date Date

TECHNICAL CONSULTANT (OPTIONAL)

___________________DATE

Accepted and approved in partial fulfillment of the Course in Science Research I.

CHAIRPERSON, SCIENCE & MATHEMATICS

____________DATE

PRINCIPAL, IDS____________

DATE

CHAPTER 1

INTRODUCTION

A. Background of the Study

Through the years, garbage has influenced people’s lives. They have

affected our world in a small way, yet brought significant outcomes. Indeed they

have become a huge part of our everyday lives. As time passes by, the problem

brought by this rubbish becomes worse.

Recycling (process in which wastes are reused) is the solution for this

problem. This process reclaims the original material and uses it in new products.

There are so many things that can be recycled-either biodegradable or not.

Example of these materials is one of the people’s common excess or trash: crab

shells. Aside from its use in the kitchen these crabs have far more use than

people have imagined.

Crabs comprise about 4,500 species of Arthropods in the order Decapoda,

class crustacean. Most crabs feed on small fishes or worms or else scavenge

along the shore or sea bottom. They help in cleaning our bodies of water. Here in

the Philippines, crabs are often used mostly in cooking.

Like almost all varieties of shells, crab shells are composed of almost 95%

Calcium Carbonate. A main component of seashells, shells of snails, oyster

shells, crab shells and etc., is a chemical compound which is calcium carbonate,

which is believed to be a potential pH buffer.

Buffer solutions contain a weak acid and a conjugate base, or a weak

base and a conjugate acid. It has a remarkable property of maintaining an almost

constant pH even though a strong acid or base is added.

B. Statement of the Problem

The potential of crushed crab shells as a pH buffer will be evaluated and

investigated in this study.

Sub-problems:

1. What is the characteristic of the different experimental pH buffer in terms

of:

a. Buffer pH; and

b. Buffer capacity?

2. Is there a significant difference in the characteristic of the different

experimental pH buffer shells in terms of:

a. Buffer pH; and

b. Buffer capacity?

3. What would be the effectiveness of the different experimental buffer on the

following type of substances:

a. Strong acid

b. Weak acid

c. Strong base

d. Weak base?

4. In what type of substance (strong acid, weak acid, strong base or weak

base) will the experimental buffer be most effective?

C. Hypothesis

1. The crushed crab shells are potential pH buffer.

2. The treatment with the higher temperature of solvent will have

a) The least change in its pH level

b) Its amount of acid or base to be added so that its pH level can

change would increase.

3. The effects of the buffer to the following substances :

a) Strong Acid – Instead of the large decrease from its original pH

level, it would be much lesser

b) Weak Acid - Instead of the relatively small decrease from its

original pH level it would be much lesser

c) Strong Base - Instead of the large increase from its original pH

level it would be much lesser

d) Weak Base - Instead of the little increase from its original pH

level it would be much lesser

4. The type of substance that the buffer will be more effective would be

the strong acid.

D. Objectives of the Study

This study generally aims to produce a pH buffer from crushed crab shells.

It also aims to:

1. find out which experimental buffer would have the most effect on the

change of the pH levels.

2. identify the characteristics of the different experimental buffer

3. determine which substance does the buffer have the most effect on.

E. Significance of the Study

Crab shells are one of the many household garbage if not disposed

properly will threaten the ecology. Crab shells have a lot of calcium carbonate.

Which have many uses in the environment, and one of it is the feasibility of being

a pH buffer.

A buffer maintains the substance’s pH level. Nowadays buffers are slowly

known because of the rapid change in our environments nature, such as

formation of acid rain.

Acid rain comes from the accumulation of acids and toxic substances

resulting from human activities such as burning of fossil-fuels. Precipitation that

has a pH value of less than 5.6 is considered to be abnormally acidic. The pH of

soil is critical to the health of vegetation and soil microorganisms.

The feasibility of creating experimental pH buffers from the shell of the

crab is just a first step in saving mother earth. Recycling should not be just done

often but it should be made a habit so that everybody can help saving our slowly

changing planet.

People in areas which are very affected with acid rains will find crab shells

helpful. The availability of nutrients in the soil for their vegetations would be

more/less maintained because of the less change in the pH level of the soil.

F. Scope and Limitations

This study focuses on determining the potential of crushed crab shells as

pH buffer to both strong and weak acid and basic solutions. This study will focus

only on crab shells and not on other potential components. We will include the

condition of some solutions (before and after the addition of pH buffer). We will

not include tests on elements, compounds, and living organisms.

G. Definition of Terms

Calcium Carbonate It is a component of animal shells and is

believed to be a potential pH buffer. For this

study, source is from crab shells.

pH It is the measure of acidity or basicity, with

lower numbers indicate it is more acidic and

higher numbers indicate it is more basic.

pH buffer It has the property that the pH of the solution

changes very little when a small amount

of strong acid or base is added to it.

Buffer pH It is the resulting sample pH after the acid/base

is added to the buffer solution.

Buffer capacity It is the maximum amount of either vinegar or

detergent that can be added before a

significant change in the pH will occur.

Experimental Buffers They are the solutions with either lukewarm

water or hot water as solvent.

CHAPTER II

REVIEW OF RELATED LITERATURE AND RELATED STUDIES

The pH concept was developed in 1909 by Soren Peder Lauritz Sorensen,

a Danish biochemist, in Carlsberg Laboratory. It was revised to the modern pH in

1924 after it became apparent that electromotive force in cells depends on

activity rather than concentration of hydrogen ions. pH concept is a convenient

method of expressing hydrogen ion concentration, which in other term the acidity

or basicity of a substance. By definition, pH=-log [H+]. (Mendoza &

Religioso, 1997)

The pH of soil determines the availability of nutrients to plants. When acid

rain infiltrates the soil, important nutrients are leached away from the soil through

runoff, into the bodies of water or other aquatic habitats.

The pH scale ranges from 0-14. A neutral solution like water has a pH

equal to 7. A pH value lower than 7, means that the solution is acidic, while a pH

value higher than 7, means that the solution is alkaline or basic. pH

measurements are important in medicine, biology, chemistry, agriculture,

forestry, food science, environmental science, oceanography, civil engineering

and many other applications. See figures and tables below. (Mendoza &

Religioso, 1997)

Figure 1: pH Scale

(http://www

.elmhurst.edu/~chm/vchembook/184ph.html, pH scale)

Table 1: pH value of common substances

Substance pH Substance pH

Hydrochloric acid 0 Urine 6.1

Gastric juice 1.6-1.8 Milk 6.3-6.6

Kalamansi 2.2 Blood 7.4

Vinegar 2.4-3.4 Baking soda 9

Apple 3.0 Detergent 9.5-10.5

Carbonated drink 3.1 Ammonia 11

Orange 3.5 Bleaching powder 12

Tomato 4.2 NaOH 14

(Mendoza & Religioso, 1997)

A way to measure the pH of a liquid is the use of pH Meter. It consists

of a special measuring probe (a glass electrode) connected to an electronic

meter that measures and displays the pH reading.

Another way to determine pH of solutions visually is by the use of pH

indicators, a halochromic solution. It causes the color of the solution to change

depending on the pH value. There are known natural indicators extracted from

red cabbage, violets, roses, camote tops, red apple skin, beets, cherries, red

onion, yellow onion, radish skin, tomato and turnip skin. See table below.

Table 2: Common Indicators

Indicator pH at which Color

Changes

Color at Lower pH Color at higher pH

Methyl Orange 4 Red Yellow

Methyl Red 5 Red Yellow

Litmus 7 Red Yellow

Phenolphthalein 9 Colorless Red

Thymophthalein 10 Colorless Blue

Alizarin yellow 11 Yellow Red

(Mendoza & Religioso, 1997)

Nature has a way of maintaining constancy. The pH of biological fluids is

maintained by buffers. A buffer solution is an aqueous solution containing a weak

acid and its conjugate base, or a weak base and its conjugate acid. It has a

remarkable property of maintaining almost constant pH even though a strong

acid or base is added to the solution.

A very good example of pH buffer is our blood, which is buffered by a

bicarbonate-carbonic acid buffer. As we know, the drinks like fruit juices that we

drink are very acidic but because our blood is a pH buffer, our blood doesn’t

lower its pH value that low. Industrially, buffer solutions are used in fermentation

processes and in setting the correct conditions for dyes used in colouring fabrics.

They are also used in chemical analysis and calibration of pH meters.

A study in 2008 conducted by Barrientos, Ponciano & Tan, which

formulated an antacid instead of pH buffer with the use of crushed oyster shells,

is similar to this study only that this study made use of crushed crab shells.

An aqueous solution is a solution in which the solvent is water. The word

aqueous means pertaining to, related to, similar to, or dissolved in water. In

these solutions within organisms, most of the water molecules are intact.

However, some of the water molecules actually break apart (dissociate) into ions.

The ions formed are called hydrogen ions (H+) and hydroxide ions (OH-). For

proper functioning of chemical processes within organisms, right balance of H+

ions and negatively charged ions, such as OH-, is critical.

Calcium carbonate, (CaCO3), which is one of the most widespread

minerals, is believed to be a potential pH buffer. It is the chief constituent of

limestone and marble, and is also the main component of the shells of marine

organisms, snails, pearls, and eggshells. Utilization of this compound for the

formulation of blackboard chalk is common. Another common utilization of

calcium carbonate is when it is used medicinally as a calcium supplement or as

an antacid, but excessive consumption can be hazardous.

Like any other marine organism with shells, crabs, which are

crustaceans characterized by a hard crust or shell, have shells comprised almost

95% of CaCO3. They have as many as 19 pairs of appendages with five pairs of

which are developed into walking legs. Their size ranges from a pea crab, which

is may be less than 1.5mm from leg tip to leg tip, to the Japanese spider crab,

which is may be 3.5m from leg tip to leg tip. (Barrientos, Ponciano & Tan, 2008)

Crabs’ gender and age, which is essential for our study, is defined by the

table below.

Table 3: Crab’s gender and age

The male crab, or jimmy, has blue

claws and an underside "apron" which

looks like an upside-down T or the

"Washington Monument." Large male

crabs are also called channelers.

The she-crab or immature female crab

has an inverted V-shaped apron.

Females have orange tipped claws.

A mature female has a widened apron

with a semicircular bell shape that

looks like the U.S. Capitol building.

She is called a sook. A Sponge Crab

is a female that has an egg mass that

looks like an orange sponge on her

belly. Let these go, so there will be

many productive crab harvests in the

future.

(http://skipjack.net/le_shore/crab/crab_ages.htm, Identifying Crab Gender and

Age)

Crabs, as a part of the phylum Anthropoda in class Crustacea, are

usually valued food to many. They feed on animal and vegetable garbage

themselves. Without them, the sea would become polluted and clogged with the

decaying animal and vegetable matter that they normally eat.

Here in the Philippines, more people recognize crabs as a yummy

recipe than a very helpful animal to our bodies of water. No matter how

challenging it is to open and collect the meat in it, Filipinos always have this dish

in most occasions. Some cook it as “Rellenong Alimango”, some as “Crab Meat

with Cauliflowers” and some as “Chilli Crabs”, but what happens after satisfying

their tummies? People throw it. Such a waste, isn’t it?

(http://www.aquaticfilipinorecipes.filipinovegetarianrecipe.com/crab_recipes.htm,

Crab Recipes)

The fate of these forlorn crab shells will be changed from being

zero to hero. Many tried to help on this mission. One study during 2009 by

Arocha turned crab shells into a chalk. But here in this study, crab shells will be

processed into a very useful solution, not only a solution that is a mixture of a

solute and a solvent, but also a solution that is an answer to the problem caused

by irresponsible disposal of crab shells.

CHAPTER III

METHODOLOGY

A. Research Design

This employs experimental research design to verify the potential of crushed crab

shells as pH buffer solution. It involves the manipulation of temperature of the solvent

used. Manipulations of variables would help determine how and why a particular event

occurs. Observation and precise gathering of data are critical factors in this study or

investigation.

The study or investigation will determine the potential of crushed crab shells as a

pH buffer solution. Two variables would be manipulated and another two variables

would be controlled. Two groups of solutions would be categorized by mature and

young crabs. Under each group, there are three set-ups of the solutions with varying

amounts of crushed crab shells (1 teaspoon, 2 teaspoons and 3 teaspoons). Set-ups

under each category would be produced twice since a base and an acid would be added

to each set-up later on. Overall, there are 16 set-ups. All solutions on both categories

would be under constant volume of water and concentration of crushed crab shells.

Since the study is most concerned with crushed crab shells' potential as pH

buffer, a base (0.1 M NaOH) or an acid (0.1 M HCl) are added to each set-ups. The pH

level of each sample of experimental buffer before and after a base or an acid is added,

are compared. Results on change in pH level in each set-up would determine the

crushed crab shells' potential as pH buffer. To come up with results of pH levels, a

digital pH meter will be used.

B. Materials and Equipments

Materials

Crab Shells

Beakers

Distilled

Water

Mortar and

pestle

Vinegar

Teaspoons

Detergent

Cups

Equipment

digital pH

meter

C. Experimental Set-up

Table 4 Varying Temperature of Solvent and Crab’s Age

Temperature of

Solvent

Mature Crab

For weak

acid

For weak

base

For strong

acid

For strong

base

Lukewarm water Set-up 1 Set-up 3 Set-up 5 Set-up 7

Hot water Set-up 2 Set-up 4 Set-up 6 Set-up 8

D. General Procedures:

Preparation of Materials

Crushing Crab Shells

Remove the thin transparent membrane attached to the inner part of the shells

for the crushing of the shell to be easier. Use mortar and pestle to crush the crabs into

powder like particle size.

Identifying the Solubility of Crushed Shells

Measure first the amount of crushed crab shells to be added on the lukewarm

and hot water. Stir thoroughly then filter the shells that didn’t dissolve. Dry the residue,

measure then subtract the amount of residue to the original amount of shells added on

the solvent. The difference would be the amount of dissolved crushed crab shells.

Preparation of Experimental Buffer Solutions

A buffer solution is an aqueous solution. Therefore, water is used as solvent

and crushed crab shells as solute. To come up with crushed crab shells, mortar and

pestle is used. Particles of the crushed crab shells must be very fine or close to powder

particles' size.

The crushed crab shells coming from mature crabs are separated. Each kind

would be then divided into varying temperature of the solvent (lukewarm water, hot

water), which are each produced twice for the addition of base and acid later. Each

measurement of crushed crab shells would be added to 100 mL of distilled water to

complete the experimental buffer. Representation of each set-up is shown on the table

4.

Calibration of the pH Meter

1. Press the power button on your digital pH meter to turn it on.

2. Calibrate your digital pH meter according to manufacturer's instructions.

Most calibrations will have you test two solutions on opposite ends of the

pH scale. As an example, you may submerge the probe into a solution

with a pH of 4, clean it off, then test a solution with a pH of 10.

3. Clean off the probe with distilled water once the calibration is successful,

and submerge the probe into the solution you want to be tested. Remove

after getting a reading, clean it off and test again just to be certain it was

accurate the first time. Record the result.

(How to Use a Digital pH Meter)

Determination of pH level

The pH of the different samples of experimental pH buffer would be initially

measured using digital pH meter. Each experimental buffer will then be subjected to

several test substances such as strong acid, weak acid, strong base and weak base one

at a time. The test substances will be added drop by drop for each samples of

experimental pH buffer. After every drop added, the experimental buffer will be stirred to

thoroughly mix, allow to settle for some time, then the pH be measured using the digital

pH meter. Addition of the test substances will stop until there is a notably big difference

in its pH, this signals that the buffer has reached its limit or buffer capacity. Total amount

of test substances will be recorded.

E. Instrument in Data Gathering

After careful experimentation and observation, data will be gathered, recorded,

evaluated and interpreted. Data would be recorded on the table below.

Table 5 Solubility of the Crushed Crab Shells at Various Temperature

Condition of

Solvent

Mature Crab

T1 T2 T3 AVE

Lukewarm water

Hot water

Table 6.1 The Effect of Strong Acid When Added on Experimental Buffers

Experimental

Buffer

Initial pH Final pHAmount of Test

Substance Used

T1 T2 T3 AVE T1 T2 T3 AVE T1 T2 T3 AVE

MLW

MHW

Legend: MLW = mature crushed crab shells in lukewarm water

MHW = mature crushed crab shells in hot water

Table 6.2 The Effect of Weak Acid When Added on Experimental Buffers

Experimental

Buffer

Initial pH Final pHAmount of Test

Substance Used

T1 T2 T3 AVE T1 T2 T3 AVE T1 T2 T3 AVE

MLW

MHW

Legend: MLW = mature crushed crab shells in lukewarm water

MHW = mature crushed crab shells in hot water

Table 6.3 The Effect of Strong Base When Added on Experimental Buffers

Experimental

Buffer

Initial pH Final pHAmount of Test

Substance Used

T1 T2 T3 AVE T1 T2 T3 AVE T1 T2 T3 AVE

MLW

MHW

Legend: MLW = mature crushed crab shells in lukewarm water

MHW = mature crushed crab shells in hot water

Table 6.4 The Effect of Weak Base When Added on Experimental Buffers

Experimental

Buffer

Initial pH Final pHAmount of Test

Substance Used

T1 T2 T3 AVE T1 T2 T3 AVE T1 T2 T3 AVE

MLW

MHW

Legend: MLW = mature crushed crab shells in lukewarm water

MHW = mature crushed crab shells in hot water

F. Statistical Tools for Data Analysis *

The data gathered will be analyzed and interpreted using appropriate

tools. The average will be used to declare results of various parameters such as

solubility of mature crushed crab shells, initial and final pH of experimental

buffers and the total amount of test substances used. ANOVA will be used in

order to know if there is a significant difference among results on each

experimental buffer.

Average Mean

Average Mean=∑X/n (where n represents the total number of values in the

sample)

ANOVA

Analysis of Variance Summary Table

Source Sum of squares d.f Mean square

Between SSb k-1 MSb

Within SSw N-k MSw

Total

In the table,

SSb= sum of square between groups

SSw= sum of squares within groups

k= number of groups

N= n1+n2+n3…+nk= sum of sample sizes for groups

MSb=SSb/k-1

MSw=SSw/N-k

F=MSb/MSw

t-test

t= [(Average mean)-µ]/ [s/√n]

Flowchart

Bibliography

BOOKS

Groiler: Encyclopedia of Knowledge (No. 5C-D) © MCMXCL Groiler

Incorporated

Vivian Corry & Christopher Cooper. (1980). New Encyclopedia of

Science (No. 4, Ca-Er) © Orbis Publishing Limited

Neil A. Campbell, Lawrence G. Mithcell & Jane B. Reece. (2000).

Biology –Concepts and Connections: International Edition © Pearson

Education Asia Pte Ltd

Estrella E. Mendoza & Teresita F. Religioso. (1997). Science and

Technology – Chemistry; Second Edition © Phoenix Publishing

House Inc.

Internet

pH color charts. (2010, February 20). Retrieved September 23, 2011,

Website:

http://www.ncsu.edu/sciencejunction/depot/experiments/water/lesso

ns/pH/

Crab’s Gender and Age. (2010, January 11). Retrieved September 23,

2011, Website: http://skipjack.net/le_shore/crab/crab_ages.htm

Crab recipes. (2010, June 18). Retrieved September 23, 2011,

Website:

http://www.aquaticfilipinorecipes.filipinovegetarianrecipe.com/crab_r

ecipes.htm

Related Study

Arocha, Izel Faith Abrasaldo. (2009). Utilization of Seashells for Chalk

Formulation (2009-No. 771)

Jutba, Danessa Ausejo. (2007). Effect of Recylced Crab Shells Unto

Hardness of Exoskeleton of Pre-Molt Mud Crabs (2007-No. 511)

Barrientos, Yasmin Nicole A.; Ponciano, Riza O.; & Tan, Katherine R..

(2008). The Potential of Crushed Oyster Shells as a Buffer.