Obtain a package of Alka-Seltzer, an antacid, from the local drug store:
b. Why does Alka-Seltzer foam and bubble when dissolved in water? Which ingredient is the antacid?

Verified step by step guidance

1. Step 1: Understand the chemical reaction that occurs when Alka-Seltzer is dissolved in water. Alka-Seltzer contains sodium bicarbonate (NaHCO₃) and citric acid (C₆H₈O₇). When these ingredients come into contact with water, they react to produce carbon dioxide gas (CO₂), which causes the foaming and bubbling.
2. Step 2: Write the chemical equation for the reaction. The reaction between sodium bicarbonate and citric acid can be represented as: ${\mathrm{NaHCO}}_3+C_6{H}_8{O}_7\to {\mathrm{Na}}_3{C}_6{H}_5{O}_7+{\mathrm{CO}}_2+H_{2}O$
3. Step 3: Identify the antacid ingredient in Alka-Seltzer. Sodium bicarbonate (NaHCO₃) is the antacid component. It works by neutralizing stomach acid (hydrochloric acid, HCl) to relieve symptoms of indigestion and heartburn.
4. Step 4: Explain the neutralization reaction of sodium bicarbonate with stomach acid. The reaction can be represented as: ${\mathrm{NaHCO}}_3+{\mathrm{HCl}}_{}\to {\mathrm{NaCl}}_{}+{\mathrm{CO}}_2+H_{2}O$
5. Step 5: Summarize the process. The foaming and bubbling occur due to the production of carbon dioxide gas during the reaction between sodium bicarbonate and citric acid. Sodium bicarbonate is the antacid ingredient that neutralizes stomach acid, providing relief from indigestion.

Key Concepts

Chemical Reaction

The foaming and bubbling of Alka-Seltzer when dissolved in water is a result of a chemical reaction between its ingredients, primarily sodium bicarbonate and citric acid. When these two compounds come into contact with water, they react to produce carbon dioxide gas, which forms bubbles and creates the characteristic fizzing effect.

Antacid Function

Alka-Seltzer contains sodium bicarbonate, which acts as the active antacid ingredient. Antacids neutralize stomach acid, providing relief from heartburn and indigestion by increasing the pH level in the stomach, thus alleviating discomfort caused by excess acidity.

Dissolution Process

The dissolution process refers to how solid substances, like the tablets in Alka-Seltzer, break down in a solvent, such as water. This process is essential for the chemical reaction to occur, as it allows the reactants (sodium bicarbonate and citric acid) to interact and produce the gas that causes the foaming effect.