6.5 moles of al (aluminum) reacts with 7.2 moles of h2o (water). which is the limiting reactant? calculate the theoretical yield. balance equation : 2al + 3 h2o == al2o3 + 3h2

1. The limiting reactant is H₂O.

2. The theoretical yield of Al₂O₃ = 978.8 g.

Explanation:

1. Which is the limiting reactant?

2Al + 3H₂O → Al₂O₃ + 3H₂,

It is clear that 2.0 moles of Al react with 3.0 moles of H₂O to produce 1.0 moles of Al₂O₃ and 3.0 mole of H₂.

∴ 4.8 mol of Al (the remaining 1.7 mol is in excess) reacts completely with 7.2 mol of H₂O with (2: 3) molar ratio.

the limiting reactant is H₂O and the excess reactant is Al.

2. Calculate the theoretical yield.

Using cross multiplication:

2.0 moles of Al produce → 1.0 moles of Al₂O₃.

4.8 moles of Al produce → ??? moles of Al₂O₃.

∴ The no. of moles of Al₂O₃ produced = (1.0 mol)(4.8 mol)/(2.0 mol) = 9.6 mol.

∴ The theoretical yield of Al₂O₃ = (no. of moles)(molar mass) = (9.6 mol)(101.96 g/mol) = 978.8 g.

n+h→nh3

we must remember that nitrogen and hydrogen are both diatomic molecules in their standard gas form. this adjusts the equation to

n2+h2→nh3

now we need to adjust coefficients in order to balance the atoms on each side of the equation. currently we have 2 atoms of nitrogen and 2 atoms of hydrogen on the reactant side and 1 atom of nitrogen and 3 atoms of hydrogen on the product side.

we can balance the hydrogens by placing a coefficient of 2 in front of ammonia and a coefficient of 3 in front of the hydrogen.

n2+3h2→2nh3

this gives us 6 hydrogen on each side and coincidentally the nitrogens now equal 2 on each side.

b. accuracy of the data matters alot more than its number of digits, organization or amount of detail. quantitative observation is more accepted than the qualitative observation.