Question

Many over-the-counter antacid tablets are now formulated using calcium carbonate as the active ingredient, which enables such tablets to also be used as dietary calcium supplements. As an antacid for gastric hyperacidity, calcium carbonate reacts by combining with hydrochloric acid found in the stomach, producing a solution of calcium chloride, converting the stomach acid to water, and releasing carbon dioxide gas (which the person suffering from stomach problems may feel as a “burp”). Write the balanced chemical equation for this process.

Short answer

The balanced chemical equation for the reaction between calcium carbonate and hydrochloric acid is: \( CaCO_3 + 2HCl \rightarrow CaCl_2 + 2H_2O + CO_2 \)

Step-by-step solution

Identify the Chemical Formulas of the Reactants and Products.

We have the following reactants and products: 1. Calcium carbonate (CaCO3): Reactant 2. Hydrochloric acid (HCl): Reactant 3. Calcium chloride (CaCl2): Product 4. Water (H2O): Product 5. Carbon dioxide (CO2): Product

Write the Unbalanced Chemical Equation.

Now that we have the chemical formulas for the reactants and products, we can write the unbalanced chemical equation: CaCO3 + HCl -> CaCl2 + H2O + CO2

Balance the Chemical Equation.

To balance the chemical equation, we need to equalize the number of atoms of each element on both sides of the equation. Currently, the equation is unbalanced as there are two chlorine atoms on the product side, while only one chlorine atom is on the reactant side. Similarly, there are two hydrogen atoms on the reactant side, while only one hydrogen atom is on the product side. To balance the equation, we need to multiply the number of molecules of hydrochloric acid (HCl) by 2 and the number of molecules of water (H2O) by 2: CaCO3 + 2HCl -> CaCl2 + 2H2O + CO2 Now the equation is balanced as there are equal numbers of atoms of each element on both sides: 1 calcium atom: 1 (reactants) = 1 (products) 1 carbon atom: 1 (reactants) = 1 (products) 3 oxygen atoms: 3 (reactants) = 3 (products) 2 hydrogen atoms: 2 (reactants) = 2 (products) 2 chlorine atoms: 2 (reactants) = 2 (products)

Write the Balanced Chemical Equation.

The balanced chemical equation for the reaction between calcium carbonate and hydrochloric acid is: CaCO3 + 2HCl -> CaCl2 + 2H2O + CO2

Key concepts

Balancing Chemical Equations

Balancing chemical equations is a fundamental skill in chemistry. It's how you ensure that the number of atoms for each element remains the same on both sides of a chemical equation. Imagine it like a seesaw, where you want everything perfectly balanced!

When we're talking about balancing equations, what we're doing is making sure that the mass and the charge are conserved—nothing gets lost in the process of a chemical reaction.

• First, identify all the reactants and products involved in the reaction.
• Write down their chemical formulas before adding coefficients to balance the equation.
• Always balance one element at a time, often starting with metals or the most complex molecule.

In our example of calcium carbonate reacting with hydrochloric acid, the initial unbalanced equation was:\[ \text{CaCO}_3 + \text{HCl} \rightarrow \text{CaCl}_2 + \text{H}_2\text{O} + \text{CO}_2 \]

By using coefficients to balance the number of each atom on both sides, we achieved:\[ \text{CaCO}_3 + 2\text{HCl} \rightarrow \text{CaCl}_2 + 2\text{H}_2\text{O} + \text{CO}_2 \]

Now, each element has the same number of atoms on both sides! This means the chemical reaction can be accurately represented and understood.

Acid-Base Reactions

Acid-base reactions are a class of chemical reactions that occur between an acid and a base. These reactions are important because they often result in the formation of water and a salt. Think of it as a neutralization reaction where the sting of an acid is neutralized by the soothing nature of a base.

In our example, hydrochloric acid \((\text{HCl})\) is the acid, and calcium carbonate \((\text{CaCO}_3)\) acts as the base. When these two react, they neutralize each other:

• The hydrogen from \(\text{HCl}\) combines with the carbonate \((\text{CO}_3^{2-})\) from \(\text{CaCO}_3\) to form water \((\text{H}_2\text{O})\).
• Calcium ions \((\text{Ca}^{2+})\) combine with chloride ions \((\text{Cl}^-)\) to form calcium chloride \((\text{CaCl}_2)\).

This process also releases carbon dioxide gas \((\text{CO}_2)\), which is why these reactions can cause fizzy sensations or burps in the context of taking an antacid.

This type of reaction not only helps with indigestion but also exemplifies the fascinating interactions between acids and bases.

Calcium Carbonate

Calcium carbonate is a common chemical compound with the formula \(\text{CaCO}_3\). It's a versatile substance found naturally in rocks like limestone, marble, and chalk, as well as in the shells of marine organisms, eggs, and snails.

In the world of chemistry and everyday life, calcium carbonate holds numerous roles:

• Used as a dietary calcium supplement: It contributes to bone health and the function of cells.
• As an antacid: Neutralizes stomach acidity, providing relief from indigestion and heartburn.
• In industry: It's utilized in the manufacture of cement and the purification of iron in blast furnaces.

Calcium carbonate's reaction with acids like hydrochloric acid is well-noted in educational syllabi due to its straightforward yet illustrative chemical reactions. This makes \(\text{CaCO}_3\) a perfect exemplar to reflect upon when learning about both chemical reactions and their balanced equations. Its ability to react and transform products efficiently highlights the practical importance of chemistry in everyday scenarios.