JEE Main 2025 Jan 23 Shift 2, Chemistry Q23: Stoichiometry

JEE Main2025Jan 23, Shift 2Chemistry

When 81.0 g of aluminium is allowed to react with 128.0 g of oxygen gas, the mass of aluminium oxide produced in grams is ____. (Nearest integer)

Given :

Molar mass of Al is 27.0 g mol $^{- 1}$

Molar mass of O is 16.0 g mol $^{- 1}$

Your answer

Solution

Balanced equation: $4 A l + 3 O_{2} \to 2 A l_{2} O_{3}$ .

Moles of Al $= \frac{81}{27} = 3$ . Moles of O $_{2}$ $= \frac{128}{32} = 4$ .

Stoichiometric demand: 3 mol Al requires $\frac{3}{4} \times 3 = 2.25$ mol O $_{2}$ , far less than the 4 mol available. So Al is the limiting reagent.

Al $_{2}$ O $_{3}$ produced $= \frac{2}{4} \times 3 = 1.5$ mol; mass $= 1.5 \times 102 = 153$ g.

Concept behind this question

StoichiometryNotes, formulas and examples →

Practice more Chemistry

Concept-wise practice with instant solutions on Fundamenthol.

Start practicing →

JEE Main 2025 Jan 23 Shift 2, Chemistry Q23: Stoichiometry

Concept behind this question

More previous year questions on Stoichiometry

Practice more Chemistry