91Ó°ÊÓ

A chemical reaction is a process where substances, known as reactants, are transformed into different substances, called products. In this exercise, we examine the thermal decomposition of calcium carbonate (\(\text{CaCO}_3\)) and magnesium carbonate (\(\text{MgCO}_3\)). When these compounds are heated, they break down into their respective oxides, calcium oxide (\(\text{CaO}\)) and magnesium oxide (\(\text{MgO}\)), along with carbon dioxide gas (\(\text{CO}_2\)). This reaction showcases how reactants are converted to forms with different chemical properties.Key points to remember about chemical reactions:

• Reactants undergo transformation during the reaction process.
• Products are created following a reaction, often with distinct characteristics compared to the reactants.
• Conservation of mass and energy principles govern these transformations, meaning the mass of the reactants must equal the mass of the products.

Understanding how the reactants \(\text{CaCO}_3\) and \(\text{MgCO}_3\) decompose into \(\text{CaO}\), \(\text{MgO}\), and \(\text{CO}_2\) upon heating provides insight into how chemical reactions can result in different products.

Mass percent calculation involves determining the portion of each component within a mixture as a percentage of the total mass. For the given problem, the goal is to find the mass percentage of \(\text{CaCO}_3\) and \(\text{MgCO}_3\) in the mixture.Here is how mass percent is calculated:1. Determine the mass of each component in the mixture.2. Divide that mass by the total mass of the mixture.3. Multiply the result by 100 to convert it to a percentage.In this problem:

• The mass of \(\text{CaCO}_3\) is calculated to be \(4.0\) grams.
• The mass of \(\text{MgCO}_3\) is found to be \(2.76\) grams.

To calculate the mass percentage:\[\text{Mass }\% \text{ of } \text{CaCO}_3 = \left(\frac{4.0}{6.76}\right) \times 100 \approx 59.17\%\]\[\text{Mass }\% \text{ of } \text{MgCO}_3 = \left(\frac{2.76}{6.76}\right) \times 100 \approx 40.83\%\]Understanding these calculations helps to discern the composition of mixtures and is crucial in fields such as chemistry and materials science.

A balanced chemical equation maintains the principle of conservation of mass. This means the number of atoms of each element is the same on both sides of the equation. Balancing equations is essential to accurately describe what happens in a chemical reaction and to perform stoichiometric calculations.For the decomposition reactions in the exercise:- The balanced equation for calcium carbonate is: \[\text{CaCO}_3 (s) \rightarrow \text{CaO} (s) + \text{CO}_2 (g)\]- The balanced equation for magnesium carbonate is: \[\text{MgCO}_3 (s) \rightarrow \text{MgO} (s) + \text{CO}_2 (g)\]In each case:

• One mole of \(\text{CaCO}_3\) decomposes to one mole of \(\text{CaO}\) and one mole of \(\text{CO}_2\).
• One mole of \(\text{MgCO}_3\) decomposes to one mole of \(\text{MgO}\) and one mole of \(\text{CO}_2\).

Ensuring that equations are balanced allows chemists to predict the quantities of products formed, which is imperative for calculating reactant and product masses. Understanding balanced equations is a cornerstone of stoichiometry, helping to make accurate quantitative predictions in chemical reactions.