Question

Which of the following are used as antacids? (A) Aluminium and magnesium hydroxide (C) Metal hydroxides (B) \(\mathrm{NaHCO}_{3}\) (D) All of these

Short answer

Aluminum and magnesium hydroxide (A) and Sodium bicarbonate \(\mathrm{NaHCO}_3\) (B) are used as antacids.

Step-by-step solution

Option A: Aluminium and magnesium hydroxide

Both aluminium hydroxide (Al(OH)₃) and magnesium hydroxide (Mg(OH)₂) are commonly used as antacids due to their ability to neutralize stomach acid, by reacting with it to form water and salt. Therefore, option A is correct.

Option B: \(\mathrm{NaHCO}_3\)

Sodium bicarbonate (\(\mathrm{NaHCO}_3\)), also known as baking soda, can act as an antacid as it can also react with stomach acid to form water, carbon dioxide, and a salt. Thus, option B is correct.

Option C: Metal Hydroxides

The category of metal hydroxides is quite broad, and it includes numerous compounds. Some metal hydroxides, such as those mentioned in option A (aluminum and magnesium hydroxide), are effective antacids. However, many other metal hydroxides may not have antacid properties, or they may be toxic for human consumption. So, option C is not a correct answer for this exercise.

Option D: All of these

Since only options A and B are correct, option D is not the correct answer. Therefore, the substances that are used as antacids among the choices given are: (A) Aluminum and magnesium hydroxide (B) \(\mathrm{NaHCO}_3\)

Key concepts

Aluminium Hydroxide

Aluminium hydroxide, often found in antacid medications, serves an important purpose for those experiencing discomfort from stomach acid. This compound, chemically represented as \( Al(OH)_3 \), has a unique ability to react with hydrochloric acid (HCl) in the stomach. When these two substances come into contact, they undergo a neutralization reaction to produce aluminium chloride, water, and some heat in the process.

Here's the chemical equation for the reaction:\[ Al(OH)_3 + 3HCl \rightarrow AlCl_3 + 3H_2O \]
While comforting for temporary relief of symptoms like heartburn or acid indigestion, users should be aware that excessive aluminum intake has been associated with health concerns. Hence, it's recommended to follow dosing instructions carefully and not rely on it for long-term use.

Magnesium Hydroxide

Similarly, magnesium hydroxide is another compound widely utilized for its antacid properties. Known by its formula \( Mg(OH)_2 \), it also neutralizes stomach acid effectively. When it reacts with hydrochloric acid, it forms magnesium chloride and water, which can reduce stomach acidity and provide relief from symptoms. The chemical equation for this reaction is:\[ Mg(OH)_2 + 2HCl \rightarrow MgCl_2 + 2H_2O \]

In addition to its antacid properties, magnesium hydroxide has a mild laxative effect, which can be beneficial for those dealing with constipation. However, it is important for users to observe proper dosages to avoid potential side effects such as diarrhea or an imbalance in the body's electrolytes.

Sodium Bicarbonate

Sodium bicarbonate, commonly known as baking soda, is a versatile compound with the chemical formula \( NaHCO_3 \). It is a bicarbonate salt, which possesses the capacity to neutralize acids, making it a valuable resource as an antacid. When sodium bicarbonate reacts with stomach acid, water, carbon dioxide gas, and sodium chloride are produced, as illustrated by the next equation:\[ NaHCO_3 + HCl \rightarrow NaCl + H_2O + CO_2 \]

Although highly effective, the production of carbon dioxide may cause belching or bloating. Additionally, due to its sodium content, those on sodium-restricted diets or with conditions such as hypertension should be cautious with its use and consult a healthcare provider before using it as an antacid.

Neutralizing Stomach Acid

Neutralizing stomach acid is a critical function of antacids like aluminium hydroxide, magnesium hydroxide, and sodium bicarbonate. Stomach acid, primarily composed of hydrochloric acid (HCl), plays a vital role in digestion but can occasionally cause discomfort by irritating the stomach lining or esophagus. Antacids work by increasing the pH level of the stomach, making it less acidic.

How Antacids Work

Antacids introduce base-forming elements that react with the acid in the stomach, leading to a neutralization reaction. This reaction forms salt, water, and, in some cases, gas. By mitigating the corrosive nature of stomach acid, antacids can relieve symptoms such as heartburn, indigestion, and upset stomach.

Considerations for Use

While antacids are helpful, it's essential for users to administer them judiciously as they may interact with other medications, and overuse can lead to side effects or a condition known as milk-alkali syndrome. It is always advised to follow the recommended dosage and to consult a healthcare professional for persistent digestive discomfort.