Ch.12 - SolutionsWorksheetSee all chapters
All Chapters
Ch.1 - Intro to General Chemistry
Ch.2 - Atoms & Elements
Ch.3 - Chemical Reactions
BONUS: Lab Techniques and Procedures
BONUS: Mathematical Operations and Functions
Ch.4 - Chemical Quantities & Aqueous Reactions
Ch.5 - Gases
Ch.6 - Thermochemistry
Ch.7 - Quantum Mechanics
Ch.8 - Periodic Properties of the Elements
Ch.9 - Bonding & Molecular Structure
Ch.10 - Molecular Shapes & Valence Bond Theory
Ch.11 - Liquids, Solids & Intermolecular Forces
Ch.12 - Solutions
Ch.13 - Chemical Kinetics
Ch.14 - Chemical Equilibrium
Ch.15 - Acid and Base Equilibrium
Ch.16 - Aqueous Equilibrium
Ch. 17 - Chemical Thermodynamics
Ch.18 - Electrochemistry
Ch.19 - Nuclear Chemistry
Ch.20 - Organic Chemistry
Ch.22 - Chemistry of the Nonmetals
Ch.23 - Transition Metals and Coordination Compounds

Solution: A stainless steel alloy is to be analyzed for its chromium content. A 5.60g sample of the steel is used to produce 250.0 mL of a solution containing Cr2O72-? A 10.0-mL portion of this solution is adde

Problem

A stainless steel alloy is to be analyzed for its chromium content. A 5.60g sample of the steel is used to produce 250.0 mL of a solution containing Cr2O72-? A 10.0-mL portion of this solution is added to BaCl2(aq). When the pH of the solution is properly adjusted, 0.145 g BaCrO 4(s) precipitates.

What is the percent Cr, by mass, in the steel sample?

Solution

We’re being asked to calculate the percent by mass (mass %) of Cr in a 5.60 g steel.

The formula for mass or weight percent is:

mass percent=mass of element in sampletotal mass of samplex100%


We must first find the mass of Cr in the 250.0 mL solution. The flow for this problem will be like this:


Mass of BaCrO4(molar mass of BaCrO4) Moles of BaCrO4(mole-to-mole comparison) Moles of Cr (molar mass of Cr) Mass of Cr in 10.0 mL portion (volume ratio) → Mass of Cr in 250.0 mL solution → Calculate for mass % Cr in steel


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