Sodium metal and water react to create sodium hydrogen and hydrogen gas through the unbalanced equation.

na + h20 — naoh h2

by determining the limiting reactant, calculate the theoretical yield of hydrogen gas (in grams) if 79.7 grams of sodium reacts with 45.3 grams of water.

Theoretical yield = 2.5 g

Explanation:

Given data:

Mass of sodium = 79.7 g

Mass of water = 45.3 g

Theoretical yield of hydrogen gas = ?

Solution:

Chemical equation:

2Na + 2H₂O → 2NaOH + H₂

Number of moles of sodium:

Number of moles = mass/ molar mass

Number of moles = 79.7 g / 23 g/mol

Number of moles = 3.5 mol

Number of moles of water:

Number of moles = mass/ molar mass

Number of moles = 45.3 g / 18g/mol

Number of moles = 2.5 mol

Now we will compare the moles of hydrogen gas with water and sodium.

                        H₂O           :             H₂

                           2             :              1

                          2.5           :            1/2×2.5 =1.25 mol

                           Na           :              H₂

                             2            :               1

                           3.5           :             1/2×3.5 =1.75 mol

water will be limiting reactant.

Theoretical yield:

Mass = number of moles × molar mass

Mass =  1.25 mol  × 2 g/mol

Mass = 2.5 g

the dependant variable is spilled water

the independent is the heat