CE 256 Lab 4 Report

docx

School

New Mexico State University *

*We aren’t endorsed by this school

Course

256L

Subject

Civil Engineering

Date

Apr 3, 2024

Type

docx

Pages

Uploaded by MegaGerbil4148

Alkalinity and Acidity Lab #4 CE 256L M02 Lab Date: 10/05/22 Report Due: 10/12/22 Group Members: Louis Mauriot, Cristian Sanchez, Omar Saucedo, Cristina Esquivel, Brittany Hymer

Table of Contents INTRODUCTION ........................................................................................................................................... 1 PROCEDURE ................................................................................................................................................. 1 RESULTS ....................................................................................................................................................... 2 DISCUSSION ................................................................................................................................................. 3 REFERENCES ................................................................................................................................................ 3 APPENDIX .................................................................................................................................................... 4 List of Tables Table 1: Alkalinity Titrations Table 2: Acidity Titrations List of Figures Figure 1: Alkalinity Equation Figure 2: Acidity Equation Figure 3: Sample Calculation of Alkalinity Figure 4: Sample Calculation of Acidity

INTRODUCTION The reaction of a strong acid with alkaline water to increase pH to a designated point can be defined as the ability of water to neutralize acids or simply put: the alkalinity of water. Carbonates (CO 3 2- ), hydroxides (OH - ) and bicarbonates (HCO 3 - ) are among the most common contributors to alkalinity in natural waters. Other contributors include but aren’t limited to silicates, phosphates or slats of weak acids. The ability to neutralize a base can be defined as the acidity of water. The most common case of biological oxidation of organic matter such as polluted water is caused by the presence of carbon dioxide (CO 2 ). This process contributes most acidity to natural water. Consequently, high corrosiveness can be found in most waters containing carbon dioxide. Titration is a common method to determine alkalinity volumetrically. There are two alternate methods to determine the end point. One is with the help of an acid and an indicator. The other method consists of using a pH meter. Titration with the assistance of a base can also be used to determine acidity. PROCEDURE Since alkalinity and acidity consist of two different experimental processes, we will be conducting two separate experiments to test each procedure. Alkalinity is the first experimental procedure. The initial step consists of pouring an amount of tap water within the range of 50-100ml into a beaker. With the help of a graduated cylinder, we record the exact volume of tap water. The indicator we used here was methyl orange. We add 3-4 drops of this latter to our tap water solution. Bromocresol green was an alternate indicator that could’ve been used. However, the recommended indicator to use for this lab was methyl orange. We use a 50ml beaker to gather a fair amount (about 50ml) of 0.02 N H 2 SO 4 . This latter is then poured into a burette. Our tap water and indicator solution is then poured into an Erlenmeyer and placed under the burette. The titration process can now begin. The endpoint is when the solution reaches a very slight pink color. The pH is also checked consistently to verify it ranges approximately 4.3. Once complete, the final pH and amount of titrated acid is recorded. The experimental procedure is repeated 2-3 times with tap water. We then switch over to pond water and repeat the entire process. All data is recorded in a table (refer to table 1 below) and the total alkalinity is calculated. Acidity is the second experimental procedure and follows an almost identical process. However, we only perform the experiment on tap water since the pH wouldn’t change for pond water. This time the color indicator changes to phenolphthalein. We add about 5 drops. This doesn’t affect the color of the solution initially. The titration process is executed until the solution turns bright pink which is the endpoint. The pH is measured and recorded. The amount of base titrated is also recorded (refer to table 2 below) and the total acidity is calculated.

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version

Access to all documents
Unlimited textbook solutions
24/7 expert homework help

RESULTS Initial pH of tap water: 7.95 Initial pH of pond water: 8.84 Table 1: Alkalinity Titrations Alkalinity Titrations using 0.02 H2SO4 & Methyl Orange Indicator Test # Water Source Sample Size (mL) Burette start (mL) Burette end (mL) Total Acid Used (mL) pH Total Alkalinity (mg/L) CaCO3 1 Tap 85 28.3 40.6 12.3 4.44 145 2 Tap 50 29 35.8 6.8 4.03 136 3 Tap 70 35.8 45.1 9.3 4.25 133 4 Pond 50 29.3 33.4 4.1 4.4 82.0 5 Pond 50 33.4 38 4.6 4.44 92.0 6 Pond 71 38 44.4 6.4 4.11 90.1 Average Alkalinity 113 Table 2: Acidity Titrations Acidity Titrations using 0.02 NaOH & Phenolphthalein Indicator Test # Water Source Sample Size (mL) Burette start (mL) Burette end (mL) Total Acid Used (mL) pH Total Acidity (mg/L) CaCO3 1 Tap 68 28.6 31.4 2.8 8.6 41.2 2 Tap 55 31.4 32.5 1.1 8.63 20.0 3 Tap 61 32.5 33.1 .6 8.47 9.84 Average Acidity 23.7 Figure 1: Alkalinity Equation Alkalinity as mg/L of CaCO3 = [(mL of acid used) *(N of acid) *(50g/eq CaCO3) *(1000 mg/g)] / (ml of sample) Figure 2: Acidity Equation Acidity as mg/L of CaCO3 = [(mL of base used) *(N of base) *(50g/eq CaCO3) *(1000 mg/g)] / (ml of sample)

DISCUSSION Alkalinity can be defined as " the buffering capacity of a water body; a measure of the ability of the water body to neutralize acids and bases and thus maintain a fairly stable pH level ". (para. 1, Alkalinity and Water | U.S. Geological Survey, n.d.) Alkalinity usually means that the pH level is greater than 7. Acidity can be defined as “the quality, state or degree of being acid” (Definition of ACIDITY, n.d.). Titration is a common method to determine alkalinity volumetrically and can also be used to determine acidity. The three major contributors to alkalinity in water are carbonates (CO 3 2- ), hydroxides (OH - ) and bicarbonates (HCO 3 - ). According to (Ali, 2022), softened water can be considered as alkaline. It has a pH of 7.5 or higher. The reason behind it is the removal of calcium and magnesium ions and replacement with sodium ions due to the water softening process. We can then conclude that the sodium ions are responsible for the increase in the water’s pH consequently increasing its alkalinity. This is the reason why the alkalinity concentration of a given water source must be considered in water softening. Alkalinity and acidity can help determine the quality of water as demonstrated in the lab we performed. By finding the pH of the titration process whether through the acidity or alkalinity process, we can determine the quality of the water we are testing and therefore determine if it is drinkable or not. Water being an essential component of the human body and to the survival of humanity, being able to determine the quality of water through alkalinity and acidity is extremely relevant to the real word. REFERENCES - Department of Civil Engineering. (2022, Fall). CE 256 lab manual. Las Cruces, New Mexico: New Mexico State University. Retrieved from class website: Alkalinity and Acidity Notes.pdf: 2022 Fall - C E-256 L-M02-ENVMTL. SCIENCE LAB (instructure.com) - Department of Civil Engineering. (2022, Fall). CE 256 lab manual. Las Cruces, New Mexico: New Mexico State University. Retrieved from class website: Alkalinity and Acidity_updated.pdf: 2022 Fall - C E-256 L-M02-ENVMTL. SCIENCE LAB (instructure.com) - Alkalinity and Water | U.S. Geological Survey . (n.d.). Www.usgs.gov. https://www.usgs.gov/special-topics/water-science-school/science/alkalinity-and-water - Definition of ACIDITY . (n.d.). Www.merriam-Webster.com. https://www.merriam- webster.com/dictionary/acidity - Ali, U. (2022, May 16). Does A Water Softener Raise Or Lower PH . Muhammad Ardhi. https://muhammadardhi.com/does-a-water-softener-raise-or-lower-ph/#:~:text=The%20pH %20scale%20measures%20how%20acidic%20or%20alkaline

APPENDIX Figure 3: Sample Calculation of Alkalinity Calculation example: (6.4*0.02*50*1000)/71= 90.1 mg/L Figure 4: Sample Calculation of Acidity Calculation example: (.6*0.02*50*1000)/61= 9.84 mg/L

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version

Access to all documents
Unlimited textbook solutions
24/7 expert homework help

CE 256 Lab 4 Report

Related Documents