Determine the theoretical and percent yield of hydrogen gas if 78.5 g water undergoes electrolysis to produce hydrogen and oxygen and 3.23 g hydrogen is collected.
theoretical yield can be determined using the equation for electrolysis of water and the mass
2H2O --> 2H2 + O2
mole of water is 78.5g/18gmol-1 = 4.36
mole ratio of H2O:H2 is 2:2 i.e. same moles. mole of H2 is 4.36x2 = 8.72moles
Theoretical mass or yield of Hydrogen is nMr = 8.72moles x 1 = 8.72g.
experimental yield is given as 3.23g
percentage yield is
(experimental/theoretical)X 100%
hope that helps
correction: theoretical mass is 8.72moles x 2 = 17.44g
To determine the theoretical and percent yield of hydrogen gas, we need to follow these steps:
Step 1: Write the balanced equation for the electrolysis of water:
2H2O → 2H2 + O2
From the equation, we can see that for every 2 moles of water (H2O), we should get 2 moles of hydrogen gas (H2).
Step 2: Calculate the number of moles of water (H2O) used:
Given mass of water = 78.5 g
To calculate moles, we need to use the molar mass of water (H2O), which is approximately 18.015 g/mol.
Number of moles of water (H2O) = Mass / Molar mass
Number of moles of water (H2O) = 78.5 g / 18.015 g/mol ≈ 4.35 mol (rounded to two decimal places)
Step 3: Determine the number of moles of hydrogen gas (H2) produced:
From the balanced equation, we see that 2 moles of water (H2O) produces 2 moles of hydrogen gas (H2).
Number of moles of hydrogen gas (H2) = Number of moles of water (H2O) × 2
Number of moles of hydrogen gas (H2) = 4.35 mol × 2 = 8.70 mol
Step 4: Calculate the theoretical yield of hydrogen gas (H2):
The theoretical yield is the maximum amount of product that can be obtained based on the balanced equation.
The molar mass of hydrogen (H2) is approximately 2.016 g/mol.
Theoretical yield of hydrogen gas (H2) = Number of moles of hydrogen gas (H2) × Molar mass
Theoretical yield of hydrogen gas (H2) = 8.70 mol × 2.016 g/mol ≈ 17.55 g (rounded to two decimal places)
Step 5: Calculate the percent yield of hydrogen gas (H2):
Percent yield is the actual yield divided by the theoretical yield, multiplied by 100%.
Actual yield of hydrogen gas (H2) = 3.23 g (given)
Percent yield of hydrogen gas (H2) = (Actual yield / Theoretical yield) × 100%
Percent yield of hydrogen gas (H2) = (3.23 g / 17.55 g) × 100% ≈ 18.4% (rounded to one decimal place)
Therefore, the theoretical yield of hydrogen gas is approximately 17.55 g and the percent yield is approximately 18.4%.