During world war ii, a portable source of hydrogen gas was needed for weather balloons, and solid metal hydrides were the most convenient form. many metal hydrides react with water to generate the metal hydroxide and hydrogen. two candidates were lithium hydride and magnesium hydride. what volume of gas is formed from 1.40 lb of each hydride at 750. torr and 27°c?

1,981.84 L of gas is formed from 1.40 lb of lithium hydride.

1,268.36 L of gas is formed from 1.40 lb of magnesium hydride.

Explanation:

Hydrogen gas from lithium hydride:

Mass of LiH = 1.40 lb = 635.0288 g

1 lb = 453.592 g

Moles of LiH =

According to reaction,1 mole of LiH gives 1 mole of hydrogen gas.

Then 79.3786 mole of LiH  will give :

of hydrogen gas.

Volume of hydrogen gas = V

Pressure of hydrogen gas , P= 750 Torr =0.987 atm

1 Torr = 0.00131579 atm

Temperature of the gas = T =  27°C = 300.15 K

Moles of gas = n = 79.3786 moles

Hydrogen gas from magnesium hydride:

Mass of = 1.40 lb = 635.0288 g

1 lb = 453.592 g

Moles of

According to reaction,1 mole of gives 2 mole of hydrogen gas.

of hydrogen gas.

Volume of hydrogen gas = V

Pressure of hydrogen gas , P= 750 Torr =0.987 atm

1 Torr = 0.00131579 atm

Temperature of the gas = T =  27°C = 300.15 K

Moles of gas = n = 50.8023 moles

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.