What is the mass of hydrogen produced when 8.0 g of sodium reacts with an excess of water to produce hydrogen and sodium
hydroxide? The equation is given.
2 Na + 2 H2O → 2NaOH + H2

Mass = 0.35 g

Explanation:

Given data:

Mass of sodium = 8.0 g

Mass of hydrogen produced = ?

Solution:

Chemical equation:

2Na + 2H₂O     →    2NaOH + H₂

Number of moles of sodium:

Number of moles = mass/molar mass

Number of moles = 8.0 g/ 23 g/mol

Number of moles = 0.35 mol

now we will compare the moles of sodium and hydrogen

             Na           :           H₂

             2             :            1

           0.35          :      1/2×0.35 = 0.175 mol

Mass of hydrogen:

Mass = number of moles × molar mass

Mass = 0.175 mol × 2 g/mol

Mass = 0.35 g

c, liquids evaporate, creating a gas