Aluminum weighing 4 g reacted with oxygen. calculate the mass of the formed alumina.

The reaction of the formation of aluminum oxide.
4Al + 3О2 = 2Al2О3.
Let’s determine the number of moles of aluminum.
n (Al) = m / Mr = 4 g / 27 g / mol = 0.15 mol.
According to the reaction equation, from 4 moles of aluminum, 2 moles of oxide are formed, and from 0.15 moles of aluminum – x mole of oxide.
n (Al2O3) = 0.15 * 2/4 = 0.075 mol.
The mass of the formed oxide.
m (Al2O3) = n (Al2O3) • Mr = 0.075 mol • 102 g / mol = 7.65 g.

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