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 number of valence electrons for each molecule or ion is shown beneath the structure. remember hydrogen will not have more than two electrons. this hydrogen is part of a covalent bond (sharing two electrons). a double bond here would cause hydrogen to share four electrons with phosphorus.

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