A sample of iron weighing 15.0 g was heated with potassium chlorate (KClO3) in an evacuated con

step 1 The given reaction is 2 molive iron plus KCLO3, AP2O3 plus KCLL. The excess mass in the iron exc

A sample of iron weighing 15.0 g was heated with potassium...

A sample of iron weighing $15.0 \mathrm{~g}$ was heated with potassium chlorate $\left(\mathrm{KClO}_{3}\right)$ in an evacuated container. The oxygen generated from the decomposition of $\mathrm{KClO}_{3}$ converted some of the Fe to $\mathrm{Fe}_{2} \mathrm{O}_{3}$. If the combined mass of Fe and $\mathrm{Fe}_{2} \mathrm{O}_{3}$ was $17.9 \mathrm{~g}$, calculate the mass of $\mathrm{Fe}_{2} \mathrm{O}_{3}$ formed and the mass of $\mathrm{KClO}_{3}$ decomposed.

Key Concepts

Conservation of Mass

This principle states that mass is neither created nor destroyed in a chemical reaction. It allows one to track the distribution of mass through reactants to products, ensuring that the total mass of the system remains constant. This concept is essential when determining the mass of an unknown component based on the differences observed before and after the reaction.

Mole Concept and Molar Mass

The mole concept provides a bridge between the macroscopic world of grams and the microscopic world of atoms and molecules. By using the molar mass of a substance (the mass per mole), one can convert between the mass of a substance and the number of moles, which is a central technique in quantitative chemical analysis and stoichiometry.

Stoichiometry and Balanced Equations

Stoichiometry involves using balanced chemical equations to determine the quantitative relationships between reactants and products. A balanced equation shows the precise ratio in which substances react, which allows for the calculation of the amount of one substance required or produced based on the amount of another.

Decomposition Reactions

A decomposition reaction is one in which a single compound breaks down into two or more simpler substances. Understanding how a compound decomposes, and the stoichiometric relationships involved, is important for determining the amount of a necessary component produced in situ for subsequent reactions.

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