Final answer:
The effect of Magnesium hydroxide, an antacid, on stomach acid is to increase the pH levels, making the stomach contents more basic and providing relief from heartburn. It neutralizes the stomach's acid through a chemical reaction with HCl. The correct answer is option: C. increases the pH
Step-by-step explanation:
The effect of an over-the-counter antacid like Magnesium hydroxide on stomach acid is to make them more basic. Milk of magnesia, which is largely Mg(OH)₂, reacts with hydrochloric acid (HCl) in the stomach during a neutralization reaction. This reaction increases the pH of the stomach content because Magnesium hydroxide is a base that reacts with the stomach's acid (HCl) to produce water (H₂O) and magnesium chloride (MgCl₂).
As pH is a measure of acidity (with lower values being more acidic and higher values being more basic or alkaline), when the pH increases, it means that the substance is becoming less acidic and more basic. Thus, the correct answer is C. increases the pH, reflecting that the substance is becoming more basic due to the antacid.
Additionally, while antacids offer relief by neutralizing stomach acid, each type can come with its own side effects. For example, magnesium-containing antacids have a laxative effect, while aluminum and calcium-containing antacids may cause constipation.