Calculate the number of moles of methane (ch4)needed to produce 7.84 g of water (h2o).

0.218 mol.

Explanation:

CH₄ + 2O₂ → CO₂ + 2H₂O,

It is clear that 1 mol of CH₄ reacts with 2 mol of O₂ to produce 1 mol of CO₂ and 2 mol of H₂O.

n = mass/molar mass = (7.84 g)/(18.0 g/mol) = 0.436 mol.

Using cross multiplication:

1 mol of CH₄ is needed to produce → 2 mol of H₂O, from stichiometry.

??? mol of CH₄ is needed to produce → 0.436 mol of H₂O.

∴ The no. of moles of CH₄ = (1 mol)(0.435 mol)/(2 mol) = 0.218 mol.

- aluminum and copper chloride.

- the chloride ion to separate the aluminum from the oxygen so that the aluminum can react with the copper ions (and the water molecules).