A compound of formula XCl₃ reacts with aqueous AgNO₃ to yield solid AgCl according to the following equation: When a solution containing 0.634 g of XCl₃ was allowed to react with an excess of aqueous AgNO₃, 1.68 g of solid AgCl was formed. What is the identity of the atom X?

Name: Chemistry
Author: McMurry
ISBN: 9781292336145

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Write the balanced chemical equation for the reaction: \[ \text{XCl}_3 + 3\text{AgNO}_3 \rightarrow 3\text{AgCl} + \text{X(NO}_3\text{)}_3 \]

Calculate the moles of AgCl formed using its molar mass: \[ \text{moles of AgCl} = \frac{1.68 \text{ g}}{\text{molar mass of AgCl}} \]

Use the stoichiometry of the balanced equation to find the moles of XCl₃ that reacted. Since 3 moles of AgCl are produced per mole of XCl₃, divide the moles of AgCl by 3.

Calculate the molar mass of XCl₃ using the mass of XCl₃ and the moles calculated: \[ \text{molar mass of XCl}_3 = \frac{0.634 \text{ g}}{\text{moles of XCl}_3} \]

Subtract the molar mass of 3 Cl atoms from the molar mass of XCl₃ to find the atomic mass of X, and identify the element X based on its atomic mass.

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Stoichiometry

Stoichiometry is the calculation of reactants and products in chemical reactions. It involves using balanced chemical equations to determine the relationships between the amounts of substances consumed and produced. In this question, stoichiometry will help relate the mass of XCl3 to the mass of AgCl formed, allowing for the identification of the element X.

Molar Mass

Molar mass is the mass of one mole of a substance, typically expressed in grams per mole (g/mol). It is crucial for converting between the mass of a substance and the number of moles, which is necessary for stoichiometric calculations. Knowing the molar mass of AgCl and the mass of AgCl produced will help determine the moles of XCl3 that reacted.

Chemical Identity and Valency

The chemical identity of an element refers to its unique properties and position in the periodic table, while valency indicates the combining capacity of an element. In this case, understanding the valency of the element X in XCl3 is essential to deduce its identity based on the number of chloride ions it can bond with, which is critical for determining the element X when combined with AgNO3.

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