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Which antacid tablet is the most effective in neutralising acid in the…
Which antacid tablet is the most effective in neutralising acid in the stomach?
Background information
What is an an antacid?
Antacids are medicines that counteract (neutralise) the acid in your stomach to relieve indigestion and heartburn. (NHS 2023)
Chemical composition varies depending on the antacid. Antacids are basic so that they neutralise the acid in the stomach.
Common brands of antacid tablets:
Alka-Seltzer
Gaviscon
Mylanta
Rolaids
TUMS
Which acid is in the stomach?
Stomach acid, also known as gastric acid is primarily made up of hydrochloric acid (HCl), and also contains pepsin and lipase. (Martinsen, Fossmark, Waldum 2019)
What is neutralisation?
When an acid and base react and create water and a salt (Dunn, Chappell n.d.)
What is an ACID?
pH less than 7
Corrode metals
taste sour
Good electrolytes
React with bases to form a salt and water
Turns blue litmus paper to red
What is a BASE?
Taste bitter, chalky
Electrolytes
React with acids to form a salt and water
pH greater than 7
Turns red litmus paper to blue
What does "effective" mean?
how well each antacid tablet neutralises the stomach acid.
effectiveness can be measured with a pH level test
The more effective an antacid, the shorter the amount of time taken for pH level to reach 7 after the antacid is added.
pH level can be measured with red cabbage water, however the change from the pH level of <7 - 7 is minor, so an inaccurate measurement may be found.
pH level can be measured with bromothymol blue, which changes from yellow to green when the pH level goes from <7 - 7.
pH level can be measured with tumeric water, however this would not work for this experiment, as there is no colour change from the pH of <7 - 7.
The more effective an antacid, the less of it needed to neutralise the hydrochloric acid to a pH level of 7.
experiment options
Option 1: 3 or more of the same antacid tablets dropped into hydrochloric acids in different conditions.
Independent variable = different conditions of hydrochloric acid
possible conditions
Other substances could be mixed into the hydrochloric acid to change its properties. For example, lemon juice.
The hydrochloric acid could be heated/cooled to different temperatures. This would impact the reaction rate, and therefore the time taken for the hydrochloric acid to reach a pH level of 7.
The hydrochloric acid could have different concentrations. Different amounts of water could be mixed in to dilute it.
Dependent variable
how long it takes for the pH level to reach 7 after adding in the antacid tablet.
limitations
A possible limitation with this experiment could be a difference between the antacid tablets that is uncontrollable. For example, the scales don't show infinite decimal places, so a small difference in the weight could be possible.
A possible limitation would be the stopwatch being stopped at slightly different points each time. One experiment, it could be stopped as soon as a green colour is seen, and the other could wait until a deeper more obvious green.
Option 2: 3 or more different types of antacid tablets dropped into 3 or more beakers of hydrochloric acid. The hydrochloric acids are all in the same conditions.
Independent variable = different types of antacids
possible substances to use as antacid tablets
Aluminum Hydroxide [Al(OH)3] (International Foundation for Gastrointestinal Disorders n.d.)
Magnesium Hydroxide [Mg(OH)2] (International Foundation for Gastrointestinal Disorders n.d.)
sodium bicarbonate (baking soda) (NaHCO3) (Higuera 2023)
Calcium Carbonate [CaCO3] (Fritz, Taylor, Parmar 2023)
Dependent variable
how long it takes for the pH level to reach 7 after adding in the antacid tablet.
limitations
The hydrochloric acids being in slightly different conditions to each other, or the scenario. For example, they may have less than a degree difference, but still be a fraction off. As this experiment is meant to mimic the stomach acid, the HCl being at a different temperature to the stomach is also a limitation.
Possible risks and how to avoid them
Someone could accidentally spill hydrochloric acid on them or another person.
Not having too much hydrochloric acid in any beaker, in order to keep it from overflowing.
Wearing correct clothing for the lab (apron, closed in shoes, safety glasses) to avoid acid touching bare skin.
All students should clean up any messes made, to avoid slips and accidental spills.
The hydrochloric acid could be mixed with a substance that makes a dangerous chemical reaction.
Students should do prior research about reactions and hydrochloric acid to ensure sure nothing they do could be dangerous.
Students should inform a teacher or experienced lab tech if anything goes wrong, or seems dangerous.
Someone in the classroom could have an allergic reaction to one of the substances used in this experiment.
Everyone who is around the experiments should wear gloves and other protective gear in order to leave as little exposed skin as possible.
People should not touch any substances with bare skin, instead, they should use tongs or spatulas and put substances into beakers rather than holding them.
Students with known allergies should inform their teacher and be cautious around potentially dangerous substances to them.
Chemical reaction in the sink if substances poured down react with each other.
The lab should have a specific place to put potentially dangerous waste.
Students should only pour things down the sink if it is safe (for example, no oil).