When aluminum is placed in concentrated hydrochloric acid, hydrogen gas is produced. 2al(s)+6hcl(aq)-> 2alcl3(aq) +3h2(g) what mass of al(s) is required to produce 513.0 ml of h2(g) at stp?

Answer : The mass of aluminium (Al) is 0.413 g

Solution : Given,

Volume of at STP = 513 ml = 0.513 L           ( 1 L = 1000 ml )

Molar mass of aluminium = 26.98 g/mole

First we have to calculate the moles of .

At STP,    

1 mole occupies 22.4 L volume

now, 0.513 L gives moles of

The moles of = 0.0229 moles

The Net balanced chemical reaction is,

From the balanced chemical reaction, we conclude that

2 moles of Aluminium (Al) produces 3 moles of hydrogen gas

Now the number of moles of aluminium required in 0.0229 moles of hydrogen gas = = 0.0153 moles

Now we have to calculate the mass of aluminium.

Mass of aluminium = number of moles × Molar mass = 0.0153 moles × 26.98 g/mole = 0.413 g

The mass of aluminium required is 0.413 g.

the electronic configuration of an atom with eight electrons is 1s²2s²2p⁴. the orbital diagrams are shown in the figure.

as per the hunds rule:

1. electrons tend to avoid being in the same orbital as per as practicable.

2. electrons in different orbitals of the same energy will have their spin parallel.

this can be illustrated from the multiplicity of the orbitals of the atom. as there are four electrons in the p orbital and p orbital has 3 sub-shells. the electrons can be fed in different ways as shown in the figure but the correct orbital diagram will be as per the hunds rule.