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

answers: to make sure that all of the broken pieces of tablet were added to the water, to allow for fair comparison of all three trials, with different particle sizes to avoid experimental error