CHEMISTRY HOMEWORK HELP

IB Chem HL Internal Assessment

To what extent does the mass of an antacid affect its ability

to neutralize the stomach’s pH level?

Introduction

Acid indigestion, more commonly known by the term “heartburn” is a stomach problem caused by the regurgitation of gastric (stomach) acid. Gastric acid is a fluid found in our digestive system, normally with a pH of around 2.0 (highly acidic on the pH scale), as it is primarily composed of HCl, KCl and NaCl and contributes to the breaking down of all the foods we digest. Heartburn results in a painful burning feeling in the chest and its duration can vary from person to person. Other symptoms include feeling as if there is food stuck in the throat and/or a burning feeling in the pharynx.

I chose to examine the pH levels of a few store-bought antacids in relation to a home remedy, in order to determine which of the two types are more effective in the neutralization of gastric acid as it undergoes heartburn, whilst evaluating the mass of each antacid. Antacids usually come in the form of a tablet/pill and are taken to help neutralize stomach acid and reduce symptoms of heartburn, as they are composed of weak bases, such as calcium carbonate or certain hydroxides, for example.

Once I was satisfied with my topic, I was able to derive my research question; To what extent does the mass of an antacid affect its ability to neutralize the stomach’s pH level?

The neutralization process focuses on the reaction of an acid and a base, resulting in the formation of a salt and water. The reaction would look something like this;

HCl + XOH → XCl + H2O

When the basic reactant, NaOH, is dissolved in water, it becomes an alkali. The products are a result of the acid and base reacting, forming water as the H+ and OH– react. The second product formed is a salt, NaCl, in this case, as the sodium (Na) and the chlorine (Cl) ions reacted. The independent variable in this investigation is the mass of the antacids, because I can choose the mass of TUMS tablets and baking soda I use in the experiment, whilst the dependent variable is the change in pH levels of the antacids; the number of acid drops required to neutralize the solution. This is measured by counting the amount of acid dropped from the burette. Also, I controlled the temperature to be constant because that might have affected the final rate of reaction and as a result, altered my data. The constant, or controlled variable, was the amount of HCl used.

Materials:

· Safety goggles

· Store-bought antacid (TUMS)

· Baking Soda

· Mortar & pestle

· Hydrochloric acid

· Balance

· Distilled water

· 6 different 100mL beakers

· Flask

· Universal pH indicators

· pH buffer solutions

· 50mL graduated cylinder

· Burette

· pH meter

Procedure:

1. Safety goggles were used throughout the entire experiment for safety precautions.

2. TUMS antacid tablet was crushed into a fine powder using the mortar and pestle.

3. The mass of the two antacids were recorded (table 1)

4. Each crushed antacid was placed in its own labelled 100ml beaker and using the graduated cylinder, 50ml of distilled water was added to each beaker and the antacids were dissolved.

5. The Universal indicators were added to each beaker and initial pH of each solution was recorded.

6. Burette was filled with hydrochloric acid solution (HCl) until it reached the “zero” line.

7. One by one, each labelled beaker was then placed under the burette and the hydrochloric acid (with pH of approximately 2.0) was added drop by drop into the beaker whilst it was being swirled until the solution was mixed thoroughly.

8. Numbers of drops were recorded until the solution finally changed colour (to a pH of approximately 7). Observations were made.

Before starting the lab, the Tums antacid tablet and the baking soda were evaluated to see what they were composed of. Starting with baking soda, its chemical formula is NaHCO3 (also called sodium bicarbonate). The Tums antacid is made up of CaCO3 (calcium carbonate), whereas the Gaviscon tablet is made of MgCO3, better known as magnesium carbonate. All three antacids provide fast relief to heartburn symptoms, however, baking soda contains a high concentration of sodium, compared to the Tums tablet; therefore it is not commonly used as a treatment to heartburn relief. Following are the antacids’ balanced chemical reactions;

Baking soda: 2HCl (aq) + 2NaHCO3 (aq) → 2CO2 (g) + 2H2O (l) + 2NaCl (aq)

Tums: 2HCl (aq) + CaCO3 (aq) → CO2 (g) + H2O (l) + CaCl2 (aq)

Gaviscon: 2HCl (aq) + MgCO3 (aq) → CO2 (g) + H2O (l) + MgCl2 (aq)

Observations/Qualitative Data

Table 1: Initial antacid mass and number of drops

Table 2: pH level comparisons (before and after HCl was added)

Table 3: Qualitative data of antacids with indicator added

Calculations and average drops required for each antacid = drops of acid____

Mass of antacid reacted

Baking soda: 110 ÷ 1.0g = 110 drops/grams

Tums : 152 ÷ 1.22g = 124.6 drops/grams

Gaviscon: 87 ÷ 0.76g = 114.5 drops/grams

***this down below is total bs I have yet to make a GOOD conclusion..

In conclusion, the bigger the tablet or antacid, the slower its rate of reaction, because there is less free space for the particles to move around, which results in an increased digestive time, causing the heartburn victim to be in pain for a prolonged time before the antacid kicks in. According to my results, the Gaviscon tablet takes less time to be digested, as its mass is the smallest (0.76), contrary to the other antacids, ranging from 1.0g to 1.22g.