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Indigestion

Have you ever eaten something and then not felt quite right afterward? Sometimes this is called indigestion or stomach upset, which happens when one or more parts of your digestive system are not functioning properly.

Have you ever heard indigestion referred to as heartburn? Heartburn does not actually occur in the heart. Instead, it is the result of stomach acid rising into the esophagus, which leads to pain in your chest.

Antacids 

Problems with the digestive system can sometimes be treated with antacids. (definition:medications used to help correct the acidity in the stomach)

Recall what you learned about the function of your stomach during the activity. The Food You Eat. Then take a look at the following commercials for antacids. While you are watching them, think about what they can tell you about the chemistry of your stomach.

 

 
 

This is an image of a thought bubble drawn in black on a white background. What Do You Think?

  • What kinds of food were shown to cause stomach upset?
  • Are these foods healthy? Why or why not?
  • What is the purpose of these commercials?
  • Based on your prior knowledge and by looking at the word and/or what you viewed in the commercials, how would you define an antacid?
  • Have you used an antacid before? Did it help you feel better?
Action.

ACTION

Acids

Stomach Acid

What is stomach acid, anyway? Stomach acid is primarily composed of hydrochloric acid with a chemical formula (definition: a set of chemical symbols showing the elements in a compound) of HCl.   

Recall that the acid in your stomach breaks down the food that you eat, turning it into liquid and making the nutrients in food available for absorption in the small intestine.  

Question

Use this interactive periodic table (by clicking on it) to determine the following:

This is an image of the periodic table with connections through images to elements and their uses in our daily lives.
Keith Enevoldsen elements.wlonk.com
 Creative Commons Attribution-ShareAlike 4.0 International License.
by 2005-2016 Keith Enevoldsen elements.wlonk.com used under ShareAlike CC BY-SA

What two elements are present in hydrochloric acid (HCl)?

Answer

Hydrogen (H) and chlorine (Cl) are the elements present in the compound hydrochloric acid (HCl).

Acidic Foods 

There are many examples of acids in our daily lives, in our bodies and even in the food we eat! 

Question

Look at the images below:

This is an image of a bunch of yellow bananas.

This is an image of two watermelon slices on a plate.

This is an image of a glass of white milk.

This is an image of a pile of citrus fruit including lemons, limes, oranges and a grapefruit.

Which of the above food items do you think are acidic?

Answer

All of them!

Properties of Acids

Chemically, you can recognize an acid because it is made up of hydrogen (H) ions which come first in its chemical formula (e.g., HCl for hydrochloric acid). Acids have the following properties, which we will explore in more detail throughout this activity.

Acids taste sour, have a pH (definition: a scale measuring how acidic a substance is) less than 7 and react with bases and carbonates.(definition:compound which has carbonate ions present (CO3), such as chalk, which has a chemical formula of CaCO3)

Properties of Bases

Bases can be recognized when the chemical formula ends with a hydroxide (OH) ion or a carbonate (CO3) ion. Bases are also referred to as alkaline.

Bases are less common in the food we eat, but are still present as ingredients like baking soda and baking powder. Bases taste bitter, have a pH greater than 7 and react with acids.

The pH Scale

The pH scale is a scale used to classify how acidic or alkaline a substance is. As you move left on the pH scale, a substance is more acidic. As you move right on the pH scale, a substance is less acidic and more alkaline, or basic.  

The pH scale is logarithmic, meaning that every change of one on the pH scale means the acidity changes by ten times. For example, a substance with a pH of 4 is ten times more acidic than a pH of 5. A substance of pH 3 is ten times more acidic than a pH of 4, but is one hundred times more acidic than a pH of 5.

This is an image of the pH scale listing numbers from 1 to 14 above coloured circles. At Number 7, there is an arrow that says neutral. There is an arrow pointing from Number 6 toward Number 0 with the label acidic. There is an arrow pointing from Number 8 toward Number 14 with the label alkaline.
The pH scale shows how acidic or alkaline a substance is. pH 7 is neutral, meaning it does not have the properties of an acid or a base.  pH values less than 7 are considered acidic, with 0 being the most acidic pH value, while pH values greater than 7 indicate a basic or alkaline substance.  A pH value of 14 is the most alkaline pH value.

pH Indicators

You can tell the pH of a substance by using indicators, such as red and blue litmus paper or universal indicator. Universal indicator is first dipped into the substance being tested. Then the colour is matched to a provided scale, as shown in the image below. For example, the substance tested below is pH 2, since the colour on universal indicator matches the colour swatch below 2.

This is an image of yellow strips of paper with a universal indicator on them. There is one yellow strip that has been dipped in acid and matches the colour of pH 2 on the universal indicator legend. Each pH value is represented by a colour ranging from red (pH 1) to dark purple (pH 14).

The pH of Bottled Water

Universal indicator can be either coloured strips of paper or in liquid form. Watch this video showing the use of universal indicator to test the pH of a variety of bottled water brands.  

 

This is an image of a thought bubble drawn in black on a white background. What Do You Think?

  • What surprised you about this video?
  • Do you consume any of these brands of water?
  • Does this video change your mind about drinking bottled water? Why or why not?
 

The pH of Common Substances

The pH scale can be used to classify many of the substances we come into contact with on a daily basis. From household cleaners and baking ingredients to the food you eat and chemicals in your school or workplace, you might be surprised at how acidic or alkaline some of these common items are.

Take a look at the image below, then answer the questions which follow.

This is an image of the pH scale of common substances. The scale goes from 0 to 14 in a range of colours from red to dark purple. There are drawings of each substance located at each pH. They are as follows: 0. battery acid 1. stomach acid 2. vinegar 3. orange juice 4. tomato 5. black coffee 6. urine 7. water 8. sea water 9. baking soda 10. indigestion tablet 11. ammonia solution 12. soapy water 13. bleach 14. drain cleaner.

This is the question/answer icon. Questions

  Use the above pH scale to answer the following questions.
  1. What is the most acidic substance? What is its pH?
    Answer

    Battery acid (pH = 0) is the most acidic.

 
  1. What is the only neutral substance? What is its pH?
    Answer

    Water (pH = 7) is the most neutral.

 
  1. How many more times acidic is orange juice than a tomato?
    Answer

    Orange juice is ten times more acidic than a tomato, because the pH scale is logarithmic.

 
  1. What is the most alkaline (basic) substance? What is its pH?
    Answer

    Drain cleaner (pH = 14) is the most alkaline substance.

 
  1. Based on its pH scale above, is an indigestion tablet an acid or a base?
    Answer

    It is a base because it has a pH of 10 (greater than 7).

 

Antacids

Antacids are medications used to manage the symptoms of indigestion and heartburn. Antacids contain active ingredients that are bases. These allow antacids to neutralize any stomach acid which could be causing digestive discomfort. This will decrease the acidity of the stomach and shift the pH to a slightly higher number on the right.

Some active ingredients(definition: ingredients in the medication that neutralize acid) in antacids include calcium carbonate (CaCO3), sodium bicarbonate (NaHCO3), magnesium hydroxide (Mg(OH)2) and aluminum hydroxide (Al(OH)3).

 

  

This is an image of a green box with white text that says Antacid with a barcode underneath. The box is beside a jar of antacid tablets that is orange with a white lid and a white label that reads Antacid.

Do you notice that each of these active ingredients has a carbonate ion (CO3) or hydroxide ion (OH)? The presence of these ions indicates that these ingredients are bases.

Antacids are effective at calming stomach discomfort because they create a neutral pH when they react with acids. Stomach acid has a pH value of 1 and an antacid tablet has a pH of 10. When they are mixed together, the pH is closer to 7, which is neutral. 

When a person is suffering from heartburn and stomach acid is pushed up against the esophagus, they experience pain because the esophagus is not specialized like the stomach to withstand acid. Using an antacid will increase the pH of the stomach, making it less acidic and relieving the pain of heartburn.

Acid Reactions

Acids react with carbonate to form carbon dioxide and water, which are neutral compounds. Here is an example of a reaction between hydrochloric acid (HCl) and calcium carbonate (CaCO3). This is similar to the reaction that would happen in the stomach after taking an antacid.  

This is an image of a balanced chemical equation. The first line of chemical names reads - hydrochloric acid + calcium carbonate --> calcium chloride (a salt) + carbon dioxide + water. The second line is the chemical formulae and reads - HCI + CaCO3 → CaCI2 + CO2 + H2O.

Acids also react with hydroxides (bases) to form salt and water. Below is an example of a typical neutralization reaction.

This is an image of a balanced chemical equation. The first line with the chemical names - reads hydrochloric acid + magnesium hydroxide --> magnesium chloride (a salt) + water. The second line is the chemical formulae and reads - HCI + Mg(OH)2 --> MgCI2 + H2O.

The above reactions are called neutralization reactions because they produce water, which is a neutral substance with a pH of 7. 

This is the Portfolio icon. Antacid Experiment

Complete the antacid experiment below and save the results in your Portfolio.

AntacidExperiment

Long Description

 
Go To Portfolio
 
Consolidation

CONSOLIDATION

This is the dropbox icon. Antacid Advertisement

A pharmaceutical company(definition: an organization that develops and sells medicine) has hired you to launch its new antacid product. Your job is to create a promotional advertisement for this new product.

Using the knowledge you gained from your experiment about how antacids work, explain why a person would need an antacid and why yours would be most effective for them.

Review the three commercials you watched earlier in this activity. This may be useful in helping you decide what to include or not include in your own advertisement. 

Yours could be in the form of a video or radio commercial, or an internet advertisement. Audio (with your voice) must be used.

Your ad must also include:

  1. a unique name for the antacid;
  2. the active ingredient in the antacid;
  3. how the antacid works (use key terms including pH, neutralization, acid, base and digestive system);
  4. how the food we eat impacts our digestive system (think about what types of food usually cause indigestion);
  5. an explanation of how neutralization reactions in the digestive system impact your life.
     

This is an image of a green check mark in a black box.Self Check  

  Antacid Advertisement Self Check
I have described how neutralization reactions in the digestive system impact my life.
I have described how antacids work using key terms (pH, neutralization, acid, base and digestive system).
I have explained how what we consume impacts our digestive system.
I have identified and described acids and bases in the digestive system using the pH scale.
I have described the process of acid-based neutralization for simple acid–base reactions.
I have explained the role of acid-based neutralization in digestive systems.

Submit Your Work
 

 

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