10.8 g of Al is burned in 8.0 g of O2: 4Al + 3O2 -> 2Al2O3. Taking Al=27, O=16, find the mass of Al2O3 formed in grams, to one decimal place.

JEE Main levelNumerical answerDifficulty 2 of 3mc064

$10.8 g$ of $Al$ is burned in $8.0 g$ of $O X_{2}$ : $4 Al + 3 O X_{2} 2 Al X_{2} O X_{3}$ . Taking $Al = 27$ , $O = 16$ , find the mass of $Al X_{2} O X_{3}$ formed in grams, to one decimal place.

Numerical answer type, answer in g, tolerance 0.05.

Al

= 0.4 mol and

O X_{2}

= 0.25 mol.

Al

needs 0.3000 mol

O X_{2}

but only 0.25 mol is present, so

O X_{2}

limits.

Al X_{2} O X_{3}

= 0.25 x 2/3 = 0.1667 mol x 102 = 17.0 g.