An organic compound was found to contain only \(\mathrm{C}, \mathrm{H},\) and Cl. When a 1.50 -g sample of the compound was completely combusted in air, \(3.52 \mathrm{~g}\) of \(\mathrm{CO}_{2}\) was formed. In a separate experiment the chlorine in a 1.00 -g sample of the compound was converted to \(1.27 \mathrm{~g}\) of AgCl. Determine the empirical formula of the compound.

The concept of stoichiometry is central to the field of chemistry and involves the calculation of the quantities of reactants and products involved in chemical reactions. It is based on the balanced chemical equation for the reaction and the mole concept, which allows chemists to relate the mass of a substance to the number of particles it contains.

Stoichiometry enables us to predict how much product will form from a given amount of reactants, or how much reactant is needed to produce a certain amount of product. In the case of the empirical formula determination exercise, stoichiometry allows us to calculate the moles of carbon, hydrogen, and chlorine from their masses and molar masses, giving us the vital ratios needed to deduce the empirical formula of the compound.

• Understanding the mole ratios in a balanced chemical equation.
• Using the mole concept to convert between mass and number of moles.
• Applying stoichiometry to infer the amounts of reactants and products.

Molar mass is defined as the mass of one mole of a given substance and is expressed in grams per mole (g/mol). It is equivalent to the atomic or molecular weight of a substance, taken from the periodic table, and normalized to grams.

The molar mass serves as a conversion factor between the mass of a substance and the amount in moles. In the textbook exercise, the molar mass of CO₂ and AgCl is used to determine the number of moles of carbon and chlorine, respectively. The mass of CO₂ and AgCl formed during the experiments is divided by their respective molar masses to find the moles of each element present.

Key points:

• The molar mass is used as a conversion factor in stoichiometric calculations.
• Obtaining the molar mass from the sum of atomic weights of elements in a compound.
• The molar mass helps us establish the relationship between mass and mole in chemical equations.

Combustion analysis is a laboratory method used to determine the elemental composition of a compound, especially those containing carbon and hydrogen. By igniting the compound in the presence of excess oxygen, it will combust fully to produce CO₂ and water. The masses of these combustion products can be measured to deduce the amounts of the constituent elements of the original compound.

In the empirical formula determination problem, combustion analysis allows us to find out how much carbon is in the sample as it is converted to CO₂. From the mass of the CO₂ produced, we can calculate the moles of carbon. This technique also plays a crucial role in ensuring the complete conversion of carbon, which aligns with the principle of the law of conservation of mass.

• Essential in identifying the proportion of carbon in organic compounds.
• Provides an accurate method to measure the content of combustible elements.
• Combustion products are analyzed to calculate the amount of the original elements.

The law of conservation of mass states that matter cannot be created or destroyed in an isolated system. In the context of a chemical reaction, this law implies that the total mass of reactants must equal the total mass of products.

When carrying out stoichiometric calculations, as shown in the empirical formula derivation, this law helps us determine masses of elements within a compound that were not directly measured. For example, in the problem at hand, once we know the mass of carbon and chlorine, we use the law of conservation of mass to infer the mass of hydrogen by subtracting the mass of carbon and chlorine from the total mass of the compound. Ensuring mass balance is integral to accurately calculating the empirical formula.

• Foundational principle in all chemical equations and reactions.
• Ensures accurate stoichiometric computations based on mass balance.
• Guides us in finding unmeasured masses within a compound.