0.45g sample of mineral ore is analyzed for chromium and found contain 0.560mg Cr2 O3. Express concentration of Cr2O3 in sample as percent

0.124% of Cr2O3 in the sample

Explanation:

A mass percent is expressed as 100 times the ratio of the mass of analyte and the mass of the sample. For this problem, the equation is:

Mass Cr2O3(g) / Mass Mineral(g) * 100

To solve this question we must convert the mass of Cr2O3 to grams and then, compute the value in the equation:

Mass Cr2O3 in g:

0.560mg * (1g / 1000mg) = 5.6x10⁻⁴g Cr2O3

Percent of Cr2O3 is:

5.6x10⁻⁴g Cr2O3 / 0.45g * 100