The Potential of Crushed Crab Shells as a pH Buffer

Marx Caesar S. BarluadoMishari Rashid M. Lucman

What is the study all about?

The study aims to determine whether crushed crab shells can be a potential pH buffer. Crushed crab shells contain calcium carbonate which is believed to be a potential pH buffer. Which then leads to production of cheaper buffers compared to commercial ones.

Statement of the Problem

The evaluation of crushed crab shells as a potential pH

buffer.

Sub-Problems

1. What is the characteristic of the experimental pH buffer in terms of:a)Buffer pH; andb)Buffer capacity?

2. What is the effectiveness of the experimental pH buffer when compared to water upon the addition of:a) Weak acidb) Weak base?

3. In what type of substance (weak acid or weak base) is the experimental buffer most effective?

4. Is there a significant difference between the trend of the pH changes of experimental buffer and water upon the addition of:a) Weak acidb) Weak base?

Scope and Limitations This study focuses on determining the potential

of crushed crab shells as pH buffer to weak acid and basic solutions. This study will focus only on crab shells and not on other potential components. We will include the comparison of the experimental buffer and the water’s change in pH upon every addition of weak acid or weak base. We will keep the volume of the solvent and the amount of the solute constant at 100 milliliters and 0.5 grams respectively. We will not include tests on elements, compounds, and living organisms.

Procedures

Use of statistical tool to summarize data

Data gathering

Determination of pH level

Calibration of pH meter

Preparation of experimental buffer solution

Preparation of Materials

Procedures

Procedures

Resulting pH levels upon the addition of base

Base Water (pH) Solution (pH)

O drops 7.3 9.86

1 drop 8.41 9.88

2 drops 8.6 9.88

3 drops 8.88 9.9

4 drops 9.14 9.91

5 drops 9.31 9.91

6 drops 9.56 9.92

7 drops 9.61 9.93

8 drops 9.68 9.93

9 drops 9.73 9.93

10 drops 9.77 9.94

11 drops 9.81 9.95

12 drops 9.84 9.96

13 drops 9.87 9.96

14 drops 9.89 9.97

15 drops 9.91 9.98

2 mL 10.07 10.04

3 mL 10.15 10.06

4 mL 10.24 10.09

5 mL 10.31 10.11

6 mL 10.34 10.14

7 mL 10.37 10.15

8 mL 10.39 10.16

9 mL 10.4 10.18

10 mL 10.4 10.19

11 mL 10.41 10.2

12 mL 10.42 10.2

13 mL 10.43 10.21

14 mL 10.43 10.22

15 mL 10.44 10.24

16 mL 10.45 10.25

17 mL 10.46 10.26

18 mL 10.48 10.27

19 mL 10.49 10.27

20 mL 10.5 10.28

21 mL 10.51 10.29

Resulting pH levels upon the addition of acid

Acid Water (pH) Solution (pH)

0 drops 7.32 9.87

1 drop 7.17 9.86

2 drops 7.07 9.85

3 drops 6.99 9.83

4 drops 6.86 9.82

5 drops 6.78 9.81

6 drops 6.7 9.79

7 drops 6.65 9.78

8 drops 6.59 9.78

9 drops 6.54 9.77

10 drops 6.48 9.76

11 drops 6.44 9.75

12 drops 6.39 9.73

13 drops 6.36 9.73

14 drops 6.33 9.73

15 drops 6.3 9.72

2 mL 6.1 9.64

3 mL 5.98 9.62

4 mL 5.89 9.59

5 mL 5.81 9.56

6 mL 5.75 9.54

7 mL 5.68 9.53

8 mL 5.6 9.51

9 mL 5.54 9.49

10 mL 5.5 9.48

11 mL 5.47 9.47

12 mL 5.43 9.45

13 mL 5.39 9.45

14 mL 5.36 9.44

15 mL 5.32 9.43

16 mL 5.29 9.41

17 mL 5.27 9.4

18 mL 5.26 9.39

19 mL 5.24 9.38

20 mL 5.23 9.38

21 mL 5.22 9.37

Analysis of Data Z-test Paired Observation at 0.05 level

of significance was used as the statistical tool.

For the Addition of Base

Hypothesis Test: Paired Observations

0.00000 hypothesized value0.06000 mean w0.01429 mean a0.04571 mean difference (w - a)0.03441 std. dev.0.00582 std. error35 n

7.86 z3.77E-15 p-value (two-tailed)

Hypothesis Test: Paired Observations

0.00000 hypothesized value0.09171 mean w0.01229 mean b0.07943 mean difference (w - b)0.19199 std. dev.0.03245 std. error35 n

2.45 z.0144 p-value (two-tailed)

For the Addition of Acid

Graph for the addition of Weak Acid

1 3 5 7 9 11 13 15 45 75 105

135

165

195

225

255

285

315

0

0.5

1

1.5

2

2.5

Changes in pH level: Water Vs. Experimental Buffer

water

experimental buffer

No. of drops

Diff

ere

nce

of

final pH

and init

ial pH

Graph for the addition of Weak Base

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 30 45 60 75 90 105

120

135

150

165

180

195

210

225

240

255

270

285

300

315

0

0.5

1

1.5

2

2.5

3

3.5

Changes in pH Level: Water Vs. Experimental Buffer

solution

water

No. of drops

Diff

ere

nce

of

final pH

and init

ial pH

Significance of the study

If proven to be a pH buffer we can create more cheaper and local pH buffers.

It can be applied to areas which are affected by acid rains

Instead of dumping the crab’s leftovers we can use them as buffers.

Conclusions1. The crushed crab shells are potential pH

buffer since changes in pH level of the experimental buffer were minimal in both the addition of weak acid and base.

2. The crushed crab shells are more effective as pH buffer during addition of weak base since the final change in pH upon addition of weak base was more minimal than in the addition of weak acid.

3. The change in pH level of the experimental buffer in every addition of weak acid or weak base is not the same with water’s change in pH level.

Recommendations

1. To use other substance that could be a source of calcium carbonate and could be a potential pH buffer.

2. To include strong base and strong acid in determining the change in pH level.

3. Find ways to fully dissolve the crab shells in water.

4. To develop the solution’s appearance close to the commercially available pH buffer.

5. To develop the potential of crab shells into a commercial buffer.

Bibliography

•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.

Bibliography•pH color charts. (2010, February 20). Retrieved September 23, 2011, Website:

http://www.ncsu.edu/sciencejunction/depot/experiments/water/lessons/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_recipes.htm

Bibliography

•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)