top-rated free essay

Acids, Bases, and Buffers Lab

By mysteriousxx8 Oct 10, 2011 998 Words
Acids, Bases and Buffers Lab

Acids, Bases and Buffers Lab
The experimental results for part one is as follows:
Part One Data Table
| Initial pH| Final pH|
Test Tube A| 6| 1|
Test Tube B| 4| 4|
Test Tube C| 4| -----|
Test Tube D| 4| 4|
Test Tube E| 6| 11|

The experimental results for part two is as follows:
Part Two Data Table
| Before CO2 was Added| After CO2 was Added|
Colour| Blue/green| Light green/yellow|
pH Level| 8.0pH| 5.0pH|

For thousands of years, people have known lemon juice, vinegar, and many other foods taste sour. However, it was not until a few hundred years ago that it was discovered that these foods tasted this way because they were all acids. In the seventeenth century, the Irish writer and amateur chemist Robert Boyle first labeled substances as either acids or bases. He noted that acids tasted sour, are corrosive to metals, change litmus red, and become less acidic when mixed with bases. On the contrary, bases felt slippery, changed litmus blue, and became less basic when mixed with acids. In the late 1800s, the Swedish scientist Svante Arrhenius believed that acids are compounds that contain hydrogen and can dissolve in water to release hydrogen and can dissolve in water to release hydrogen ions into solution. He also defined bases as substances that dissolve in water to release hydroxide ions into solution. Finally, in 1923, the Danish scientist Johannes Bronsted and the Englishman Thomas Lowry altered Arrhenuis’ theory slightly, saying acids and bases are substances that are capable of splitting off or taking up hydrogen ions respectively. In 1909, the Danish biochemist Sören Sörensen invented the pH scale for measuring acidity. The pH scale ranges from 0 to 14, where substances with a pH between 0 and less than 7 are acids, substances with a pH greater than 7 and up to 14 are bases, and a substance is considered neutral when they have a pH level of 7.

In part one of the acids, bases and buffers lab, only the pH levels of test tube A changed over the course of the experiment. The initial pH in test tube A was 6, and the final pH was 1. This shows that when 5mL of the 0.1M hydrochloric acid was added, the pH level dropped, causing the substance in test tube A to become more acidic. The hydrochloric acid completely ionized in the water, making it as strong as H3O+ due to the leveling effect of water. While in test tube B, the initial and final pH levels remained at 4 even though 5mL of 0.1M hydrochloric acid was added to the buffer solution. When the hydrochloric acid was added to this buffer, the added hydronium ion reacted with the strongest base in the medium, namely the acetate ion, and formed more acetic acid. This reaction consumed the added hydronium ion, preventing the pH levels from rising drastically and was responsible for the buffering effect. As a result of adding acid to the buffer, the concentration of acetate decreased and the concentration of acetic acid increased. The solution acted as a buffer because nearly all of the added hydronium ion is consumed by reaction with acetate. Thus, because of the buffer solution in test tube B, the pH levels remained the same while the pH levels in test tube A decreased.

In test tube D, the initial pH and final pH remained constant at a level of 4. The results remain the same because of the buffer. When sodium hydroxide was added to the buffer solution, the hydroxide ions were removed when they reacted with the acetic acid molecules. This prevented the pH of the solution from significantly rising, which it would have if the buffer solution was not present. While in test tube E, the initial pH was 6 and the final pH was 11. This is so because sodium hydroxide was added to the distilled water, resulting in the solution to become basic since the concentration of OH- decreased. The final test tube, which was test tube C, had an initial pH of 4. This would be considered the control, as it acted as a constant for the other test tubes to be compared to throughout the experiment. It was important to have test tube C to stay constant so that in the end, all of the test tubes would have different solutions in them. For example, in the end test tube A contained an acidic solution, test tube B had a buffered solution where an acidic solution was added, test tube D had a buffered solution where a basic solution was added, test tube E had a basic solution, and finally test tube C had a buffered solution which was left untouched. Thus, test tube C played an important role in the lab.

Buffering is extremely important in the human system. One of the uses of buffering in the body is to control the pH levels in the blood. This buffer system is composed of carbonic acid and the bicarbonate ion. When the blood becomes more basic than it should be, the carbonic acid is released, which brings the blood back up to the pH level it should be. Also, when carbonic acid is used, it forms the bicarbonate ion after the hydrogen has been donated. The same applies when the blood becomes too acidic. The bicarbonate ion is released bringing the pH back up to where it should be and producing carbonic acid. Other examples of buffering takes place during biochemical reactions involved in vital processes like metabolism, respiration, the transmission of nerve impulses and muscle contraction and relaxation take place within a narrow pH range. Without the buffering systems, human beings would not be able to survive.


Cite This Document

Related Documents

  • Acid-Base Buffers

    ...CHEMICAL REACTIONS: ACID-BASE BUFFERS Short Overview Acids and bases represent two of the most common classes of compounds. Many studies have been done on these compounds, and their reactions are very important. Perhaps the most important reaction is the one in which an acid and base are combined, resulting in the formation of wate...

    Read More
  • Acid-Base Lab

    ...Title: Acid-Base Titrations AP Chemistry Laboratory #6 II.Purpose: The purpose of this experiment is to standardize a sodium hydroxide solution and use the standard solution to titrate an unknown solid acid. The equivalent mass of the solid acid will be determined from the volume of sodium hydroxide added at the equivalence point. The equilibri...

    Read More
  • Acid- Base Titration Lab

    ... Acid-Base Titration and Volumetric Analysis The purpose of this experiment is to determine the [NaOH] of a solution by titrating it with standard HCl solution, to neutralize a known mass of an unknown acid using the NaOH solution as a standard, to determine the moles of NaOH required to neutralize the unknown acid, and to calculate the m...

    Read More
  • Acids, Bases, Buffers and Respiration

    ...ids Acids, Bases, Buffers and Respiration Darlene E. McDonald WCCC Fall 2012 Ap Lab 071-07 Dr. Roxanne Levandosky August 31, 2012 I. INTRODUCTION: A.PURPOSE: a. To define and understand the key terms. ~acid ~buffer system ~base ~acidosis ~pH ~alkalosis ~pH scale ~hypoventilation ~pH indicators ~hyperven...

    Read More
  • Lab Acid Base Homeostasis

    ...Electrolyte, and Acid-Base Balance: Acid-Base Homeostasis 1. List the three important buffer systems in the body: protein buffer systems 1. _______________________________________________________________________ carbonic acid- bicarbonate system 2. _______________________________________________________________________ phosphate buffer system ...

    Read More
  • Acids, Bases & Buffers

    ...Title: Acids, Bases & Buffers Objectives: 1. To understand the acid-base chemistry. 2. To prepare and evaluate a buffer system 3. To measure the buffering capacity of two types of isotonic drinks. Introduction: There are acid-forming, basic forming and neutral food, however the acid or alkaline properties of a food is unable to judge b...

    Read More
  • Acid Base Titration Lab

    ...DKFLSDFKLFKJ | Acid-Base Titration. | kfjhdkjhvdkfj | | April Jowers | 12/19/2012 | DKFJSDKJFHDSKJHF | Introduction In this lab we will use basic titrating skills and techniques in order to titrate HCl. We will also be practicing how to prepare the solution. Using the titration data, we can practice our stoichiometric skills ...

    Read More
  • Chemistry Lab properties of acids and bases

    ... 4/2/14 Period: 1st Chemistry Sour Acids and Bitter Bases Purpose: The purpose of this lab was to observe the different reactions formed between various acids and bases with the aid of indicators. Equipment: 1. Safety goggles. 2. Droppers. 3. Red Litmus paper. 4. Blue Litmus paper. 5. pH paper. 6. Well plate. 7. Micro spatul...

    Read More

Discover the Best Free Essays on StudyMode

Conquer writer's block once and for all.

High Quality Essays

Our library contains thousands of carefully selected free research papers and essays.

Popular Topics

No matter the topic you're researching, chances are we have it covered.