The discovery of hafnium, element number 72, provided a controversial episode in chemistry. G. Urbain, a French chemist, claimed in 1911 to have isolated an element number 72 from a sample of rare earth (elements 58–71) compounds. However, Niels Bohr believed that hafnium was more likely to be found along with zirconium than with the rare earths. D. Coster and G. von Hevesy, working in Bohr's laboratory in Copenhagen, showed in 1922 that element 72 was present in a sample of Norwegian zircon, an ore of zirconium. (The name hafnium comes from the Latin name for Copenhagen, Hafnia). (c) Solid zirconium dioxide, ZrO2, reacts with chlorine gas in the presence of carbon. The products of the reaction are ZrCl4 and two gases, CO2 and CO in the ratio 1:2. Write a balanced chemical equation for the reaction.

Verified step by step guidance

1. Identify the reactants and products in the reaction: ZrO_2 (solid), Cl_2 (gas), and C (solid) are the reactants, while ZrCl_4 (solid), CO_2 (gas), and CO (gas) are the products.
2. Write the unbalanced chemical equation: ZrO_2 + Cl_2 + C -> ZrCl_4 + CO_2 + CO.
3. Balance the zirconium (Zr) atoms: There is 1 Zr atom on both sides, so they are already balanced.
4. Balance the chlorine (Cl) atoms: There are 4 Cl atoms in ZrCl_4, so you need 2 Cl_2 molecules on the reactant side to provide 4 Cl atoms.
5. Balance the carbon (C) and oxygen (O) atoms: Use the given ratio of CO_2 to CO (1:2) to balance the carbon and oxygen atoms, ensuring the total number of each type of atom is the same on both sides of the equation.

Key Concepts

Balancing Chemical Equations

Balancing chemical equations is a fundamental skill in chemistry that ensures the law of conservation of mass is upheld. This law states that matter cannot be created or destroyed in a chemical reaction, meaning the number of atoms of each element must be the same on both sides of the equation. To balance an equation, coefficients are adjusted in front of the chemical formulas to achieve equal numbers of each type of atom. This process is crucial for accurately representing the stoichiometry of a reaction.

Stoichiometry

Stoichiometry is the quantitative relationship between the reactants and products in a chemical reaction. It allows chemists to predict the amounts of substances consumed and produced in a reaction based on balanced equations. Understanding stoichiometry is essential for calculating yields, determining limiting reactants, and scaling reactions for practical applications. In the context of the given reaction, stoichiometry helps in understanding the molar ratios of reactants and products involved.

Chemical Reaction Types

Chemical reactions can be classified into several types, including synthesis, decomposition, single replacement, and double replacement reactions. The reaction described in the question involves the synthesis of zirconium tetrachloride (ZrCl4) from zirconium dioxide (ZrO2) and chlorine gas (Cl2), with carbon acting as a reducing agent. Recognizing the type of reaction helps in predicting the products and understanding the mechanisms involved, which is vital for writing accurate balanced equations.