When 6.0 mol H2O reacts with 5.0 mol Al in the reaction below, 4.0 mol of Al are used up in the reaction. How many moles of Al are left over unreacted?

Reaction: 2Al + 3H2O → Al2O3 + 3H2

1 mole

Explanation:

Given parameters:

number of moles of H₂O = 6moles

Number of moles of Al  used up= 4 moles

Number of moles of Al given = 5 moles

Unknown:

Number of moles of Al left unreacted = ?

Solution

To solve this problem, we are going to use the mole approach. The balanced chemical equation furnishes us with an overview of the amount of reactants used in the reaction.

 The balanced equation is shown below:

            2Al + 3H₂O → Al₂O₃ + 3H₂

we can also see that 4 moles of aluminium was used up in the reaction.

The amount of unreacted aluminum = Number of moles given - number of moles used

                    = 5 mole - 4 mole

                     = 1 mole

vanderwaal's forces of attraction are the electrostatic intermolecular forces that exist in a molecule due to the temporary or permanent dipoles that are developed in a molecule. in , the major intermolecular forces are dipole-dipole interactions as the molecule is polar (bent structure). so the vanderwaal's forces of interaction in between molecules are the permanent dipole-dipole interactions that develop due to the dipole that exists in between the polar h - s bond. the positively charged hydrogen atom is attracted towards the negative end of the dipole that is sulfur of the adjacent molecule. therefore, these forces of attraction are relatively stronger than that of london dispersion forces that exist in non polar molecules.