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Ch.3 - Molecules, Compounds & Chemical Equations
Chapter 3, Problem 141

A chromium-containing compound has the formula FexCryO4 and is 28.59% oxygen by mass. Find the values of x and y.

Verified step by step guidance
1
Start by assuming 100 g of the compound FexCryO4, which means you have 28.59 g of oxygen.
Calculate the moles of oxygen using its molar mass (16.00 g/mol): \( \text{moles of O} = \frac{28.59 \text{ g}}{16.00 \text{ g/mol}} \).
Let the molar mass of the compound be \( M = x \times \text{molar mass of Fe} + y \times \text{molar mass of Cr} + 4 \times \text{molar mass of O} \).
Set up the equation for the mass percentage of oxygen: \( \frac{4 \times 16.00}{M} \times 100 = 28.59 \).
Solve the equation for \( M \), and use the known molar masses of Fe and Cr to find the values of \( x \) and \( y \).