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:

$\overline{){\mathbf{mass}}{\mathbf{}}{\mathbf{percent}}{\mathbf{=}}\frac{\mathbf{mass}\mathbf{}\mathbf{of}\mathbf{}\mathbf{element}\mathbf{}\mathbf{in}\mathbf{}\mathbf{sample}}{\mathbf{total}\mathbf{}\mathbf{mass}\mathbf{}\mathbf{of}\mathbf{}\mathbf{sample}}{\mathbf{x}}{\mathbf{100}}{\mathbf{\%}}}$

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 BaCrO_{4}**(molar mass of BaCrO _{4})**→ Moles of BaCrO

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 Cr_{2}O_{7}^{2-}? A 10.0-mL portion of this solution is added to BaCl_{2}(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?

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