6. A chemist needs 457.8 g of KMnO4 to make a solution. How many moles of KMnO4 is that? 7. How many moles of erythromycin (C37H67N013), a widely used antibiotic, are in 1.00 x 10°g of the
substance?
8. Cortisone (C21H2805) is a synthetic steroid that is used as an anti-inflammatory drug. How many moles of
cortisone are present in one 10.0 mg tablet?

6) 2.9 moles of KMnO4

7) 1.36×10^-3 moles

8) 2.8×10^-5 moles

Explanation:

6) Number of moles is given as mass/molar mass

Mass of KMnO4= 457.8

Molar mass of KMnO4= 158.034 g/mol

Number of moles of KMnO4= 457.8 g/ 158.034 g/mol= 2.9 moles of KMnO4

7) mass of erythromycin= 1.00×10^0 g

Molar mass of erythromycin= 733.93 g/mol

Number of moles of erthromycin= 1.00×10^0 g/ 733.93 g/mol = 1.36×10^-3 moles

8) mass of cortisone= 10.0 mg= 10×10^-3g

Molar mass of cortisone= 360.45 g/mol

Number of moles of cortisone= mass/molar mass= 10×10^-3 g/ 360.45 g/mol = 2.8×10^-5 moles