Regents Chemistry June 2026 35 Given the balanced equation representing a reaction: 4Al(s) + 3O2(g) → 2Al2O3(s) + energy What is the number of moles of Al2O3 formed when 3.00 moles of Al reacts completely with oxygen? (1) 1.50 mol (2) 2.25 mol (3) 6.00 mol (4) 4.00 mol Solution: The coefficients in the equation represent moles. This equation tells us for 4 moles of Al, 2 moles of Al2O3 will be produced. Therefore, the number of moles of Al2O3 will by half of the moles of Al.

Regents Chemistry June 2026 34 Given the balanced equation representing a reaction: 2LiOH + energy → Li2O + H2O What is the mass of Li2O produced when 4.8 grams of LiOH reacts completely to produce 1.8 grams of H2O? (1) 4.2 g (2) 6.6 g (3) 3.0 g (4) 7.8 g Solution: According to the law of conservation of mass, the mass of reactants (left of the arrow) is equal to the mass of the products(right of the arrow). 4.8=1.8+x x=4.8-1.8=3.0g, choice 3 is the correct answer. LINKS: Re