Question

Within the limits of experimental error, show that the law of conservation of mass was obeyed in the following experiment: \(10.00 \mathrm{g}\) calcium carbonate (found in limestone) was dissolved in 100.0 mL hydrochloric acid \((d=1.148 \mathrm{g} / \mathrm{mL}) .\) The products were \(120.40 \mathrm{g}\) solution (a mixture of hydrochloric acid and calcium chloride) and 2.22 L carbon dioxide gas \((d=1.9769 \mathrm{g} / \mathrm{L})\)

Short answer

The law of conservation of mass is confirmed in this experiment as the total mass of the reactants (124.8 g) is approximately equivalent to the total mass of the products (124.78 g), within the limits of experimental error.

Step-by-step solution

Calculate the mass of the hydrochloric acid

First, recall that density is mass/volume. Therefore, the mass of the hydrochloric acid is equal to its density times its volume, which is \(1.148 \mathrm{g/mL} \times 100.0 \mathrm{mL} = 114.8 \mathrm{g}\).

Calculate the total mass of the reactants

Add the mass of the calcium carbonate and the mass of the hydrochloric acid to find the total mass of the reactants. This equals \(10.00 \mathrm{g} + 114.8 \mathrm{g} = 124.8 \mathrm{g}\).

Calculate the mass of the carbon dioxide

Again, using the density is mass/volume formula, the mass of the carbon dioxide is \(1.9769 \mathrm{g/L} \times 2.22 \mathrm{L} = 4.38 \mathrm{g}\).

Calculate the total mass of the products

Add the mass of the solution and the mass of the carbon dioxide to find the total mass of the products. This equals \(120.40 \mathrm{g} + 4.38 \mathrm{g} = 124.78 \mathrm{g}\).

Compare the total mass of the reactants with the total mass of the products

Comparing the total mass of reactants and the total mass of products, they are \(124.8 \mathrm{g}\) and \(124.78 \mathrm{g}\), respectively, which within the limits of experimental error, are equivalent thus confirming the law of conservation of mass.

Key concepts

Calcium Carbonate

Calcium carbonate is a common chemical compound that is interesting in many ways. It is found naturally in rocks like limestone, chalk, and marble. When you look at a piece of chalk or a marble statue, you are seeing calcium carbonate in action.
In chemistry, its formula is written as \(\text{CaCO}_3\). This indicates that it is made from one calcium atom (Ca), one carbon atom (C), and three oxygen atoms (O).
The primary use of calcium carbonate is to neutralize acids. This is due to its nature as a basic compound. When it reacts with an acid, it forms new substances that typically include carbon dioxide gas and water.

• Neutralizes acids: Calcium carbonate can neutralize excess acids.
• Non-toxic: It's safe enough to be ingested and is found in many antacids.
• Natural occurrence: Widely found in many geological formations.

Hydrochloric Acid

Hydrochloric acid (HCl) is a strong and corrosive acid commonly found in the laboratory and in our stomachs as part of gastric juice. It plays a big role in chemical reactions involving metals and carbonates.
Since it is composed of hydrogen (H) and chlorine (Cl), it is known to readily dissolve in water, creating a strong acidic solution.
This acid has several important uses, including in industrial applications and for balancing pH levels in pools. However, it is essential to handle it with care because of its strong corrosive nature.

• Strong acid: It's highly acidic and can corrode materials quickly.
• Industrial uses: Used in the production of chlorides and fertilizers.
• Biological presence: Found in the human stomach and helps in digestion.

Chemical Reactions

Chemical reactions occur when substances interact to form new products. These can include changes in physical properties, energy, and composition.
Reactions can be classified into different types, like synthesis, decomposition, single replacement, and double replacement.
In our specific example, calcium carbonate reacts with hydrochloric acid. They undergo a chemical reaction to form a solution of calcium chloride and carbon dioxide gas.

• Reactants: The starting materials that react together, such as calcium carbonate and hydrochloric acid in this scenario.
• Products: The end result of a chemical reaction, like calcium chloride and carbon dioxide here.
• Conservation of mass: The total mass of products equals the total mass of reactants in a closed system.