Question

What is the quantity of hydrogen gas liberated when 46 g of sodium reacts with excess ethanol?
[Given At. mass of Na = 23]
A. \[2.4\times {{10}^{-3}}\]Kg
B. \[2.0\times {{10}^{-3}}\]Kg
C. \[4.0\times {{10}^{-3}}\]Kg
D. \[2.4\times {{10}^{-2}}\]Kg

Answer 1

Hint: Mole is generally represented by the symbol mol. It is generally used as a unit of measurement for the amount of substance in the SI units where SI stands for International System of Units. A mole of a substance can also be defined as having exactly $6.02214076\times {{10}^{23}}$ particles and those particles may be atoms, molecules, ions, or electrons.

 Complete answer:
Hydrogen gas is represented by molecular formula \[{{H}_{2}}\]whereas ethanol is represented by \[{{C}_{2}}{{H}_{5}}OH\], the suffix ol is used due to the presence of alcoholic group. Sodium is represented by Na it is generally a metal and reaction of sodium and ethanol can be shown as:
$2Na+{{C}_{2}}{{H}_{5}}OH\to 2{{C}_{2}}{{H}_{5}}ONa+{{H}_{2}}$
Above statement is proven to be true that \[{{H}_{2}}\]is liberated when sodium and ethanol react with each other. Now we have to find the quantity of hydrogen gas liberated during this reaction which is generally calculated by calculating the moles of sodium ions.
Mole is generally represented by the term mol and it can be easily calculated by dividing the mass of the chemical compound with the molar mass. Hence moles of 46 g of Na is given by:
$\dfrac{Given Mass}{MolarmassofNa}=\dfrac{46}{23}$= 2 mol
2 mol of Na gives 1 mole of hydrogen
And we know that molecular weight of hydrogen is $2g/mol$
Thus the quantity of \[{{H}_{2}}\]gas is 2 g or \[2.0\times {{10}^{-3}}\]kg.

 Hence option B is the correct answer.

 Note:
Hydrogen is kept in the category of non-metal represented by the chemical symbol H. The molecular formula of hydrogen is\[{{H}_{2}}\]. Hydrogen is used as a convenient and clean burning fuel. Hydrogen gas can be stored as a compressed gas or liquid.