Question

What mass of oxygen will react with 16.6 g of aluminum according to the following reaction?

4 Al + 3 O₂ ? 2 Al₂O₃

Answer 1

From the equation we can say that,

4 moles of Al reacts with 1 mole of O2 to give 2 moles of Al2O3

Now,

molar mass of Al = 26.981538 g/mol

molas mass of O2 = 32 g/mol

Convert 16.6 g of Al into moles of Al,

moles of Al = g of Al / molar mass of Al

                   = 16.6 / 26.981538

                   = 0.615 moles

Since 4 moles of Al react with = 3 moles of O2

Therefore, 0.615 moles of Al will react with = 0.615 x 3 / 4

                                                                     = 0.461 moles

Convert 0.461 moles into mass of oxygen,

mass of oxygen = moles x molar mass

                          = 0.461 x 32

                          = 14.77 g

Thus, 14.77 g of O2 will react with 16.6 g of Al