Question

13. Aluminum oxide

a.  a MW of 101.96 g/mol. How many moles of ALUMINUM would be in 10200 g aluminum oxide?   

b. a MW of 101.96 g/mol. How many grams of aluminum oxide would be in 100 moles aluminum oxide?

c.  a MM of 102 g/mol. How many oxygen atoms would be in 204 g aluminum oxide?

d. What is the mass of oxygen in 204 g aluminum oxide?

Answer 1

Molar mass of Al is 26.98 g/mol

Chemical formula of aluminum oxide is Al2O3

in one moles 2 mol Al is present

Thus mass of Al in 10200 g = 2 x 26.98 x 10200/101.96 = 5398.11 g

b.

Mass of Aluminium oxide = number of moles x molar mass

given that number of moles = 100 moles

molar mass = 101.96 g/mol

mass of Aluminum oxide = 101.96 x 100 = 10196 g

c. Number of moles of Al2O3 = mass in g/ molar mass = 204/102 = 2

As per the formula, one-mole Aluminum oxide contains 3 moles O atoms

Thus total number of moles of oxygen atoms = 6

One mole of all substance contains 6.022 x 10²² atoms

total number of oxygen atoms = 6 x  6.022 x 10²² = 36.132 x 10²² atoms

d.

mass of oxygen = 48 g in 102 g (note that 3 oxygen atoms are present in one Al2O3)

thus in 204 g, 96 g oxygen is present.

mass of oxygen atom = 96 g