The gleaming metallic appearance of the Gateway Arch in St. Louis, Missouri, comes from the stainless steel used in its construction. This steel is made mostly of iron, but it also contains 19% (by mass) chromium and 9.0% (by mass) nickel. Stainless steel maintains its metallic sheen because the chromium and nickel in it combine with oxygen from the atmosphere, forming a layer of Cr2O3 and NiO that is too thin to detract from the luster of the steel but that protects the metal beneath from further corrosion. What is the mole ratio of chromium to nickel atoms in this steel?

the mole ratio of chromium to nickel atoms in the steel is 2.383

Explanation:

Given the data in the question;

Chromium  = 19% ( by mass )

Nickel = 9% ( by mass )

now, let the mass of the steel = 100 g

so mass of Chromium  = 19g

mass of nickel = 9g

We know that; Atomic mass of Cr is 52 g/mol, Atomic mass of Ni is 58.7 g/mol

Moles of Cr =  mass/atomic number = 19/52 mol

Moles of Ni =  mass/atomic number = 9/58.7 mol

The mole ratio of of Cr to Ni atom  will be;

⇒ Moles of Cr / Moles of Ni

= (19/52) / (9/58.7)

= 19×58.7 / 9×52

= 2.383

Therefore, the mole ratio of chromium to nickel atoms in the steel is 2.383

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