posted by Zak .
11. Chromium is produced by reacting its oxide with aluminum. If 76g of Cr2O3 and 27g of Al completely react to form 51g of Al2O3, how many grams of Cr are formed?
This is a limiting reagent problem. Most are solved the same way. However, this one has a short cut you can use.
Write an equation and balance it.
Convert 51 g Al2O3 to moles. moles = grams/molar mass.
Using the coefficients in the balanced equation, convert moles Al2O3 to moles Cr.
Now convert moles Cr to grams. g = moles x molar mass.