Question

13.What volume of hydrogen gas is produced when 92.4 g of sodium reacts completely according to the following reaction at 25 °C and 1 atm?
sodium (s) + water(l)------->sodium hydroxide (aq) + hydrogen(g)

Answer 1

Answer:

44.8L of hydrogen gas

Explanation:

The reaction expression is given as:

            2Na   +  2H₂O   →    2NaOH    +  H₂

Given parameters:

Mass of sodium  = 92.4g

Unknown:

Volume of hydrogen gas  =  ?

Solution:

To solve this problem:

            1 mole of a substance at STP occupies a volume of  22.4L

Let us find the number of moles of the hydrogen gas;

 Number of moles of Na = $\frac{mass}{molar mass}$  

      Molar mass of Na = 23g/mol

 Number of moles  = $\frac{92.4}{23}$    = 4.02mole

From the balanced reaction expression:

       2 mole of Na will produce 1 mole of hydrogen gas

     4.02 mole of Na will produce $\frac{4.02}{2}$   = 2mole of hydrogen gas

So

         1 mole of a substance at STP occupies a volume of  22.4L

        2 mole of hydrogen gas will occupy a volume of 2 x 22.4  = 44.8L of hydrogen gas