oleum or fuming sulfuric acid available commercially in concentration rnaging from 20 to 99.9% sulfur trioxide.
What is the percnet by mass of sulfur trioxide if oleum is expressed as 3H2SO4 5SO3?
To find the percent by mass of sulfur trioxide in oleum (expressed as 3H2SO4 5SO3), we need to calculate the molar masses of sulfur trioxide and oleum and compare them.
Here's how you can calculate it step by step:
1. Calculate the molar mass of sulfur trioxide (SO3):
- Sulfur (S) atomic mass = 32.06 g/mol
- Oxygen (O) atomic mass = 16.00 g/mol (3 oxygen atoms in SO3)
Molar mass = (32.06 g/mol) + (16.00 g/mol x 3) = 80.06 g/mol
2. Calculate the molar mass of oleum (3H2SO4 5SO3):
- Hydrogen (H) atomic mass = 1.01 g/mol (2 hydrogen atoms in H2SO4)
- Sulfur (S) atomic mass = 32.06 g/mol
- Oxygen (O) atomic mass = 16.00 g/mol (4 oxygen atoms in H2SO4)
Molar mass = (1.01 g/mol x 2) + (32.06 g/mol) + (16.00 g/mol x 4) + (80.06 g/mol x 5) = 496.35 g/mol
3. Calculate the percent by mass of sulfur trioxide in oleum:
- Mass of sulfur trioxide = (80.06 g/mol x 5) = 400.30 g/mol
- Mass of oleum = 496.35 g/mol
Percent by mass = (mass of sulfur trioxide / mass of oleum) x 100
= (400.30 g/mol / 496.35 g/mol) x 100
≈ 80.68%
Therefore, the percent by mass of sulfur trioxide in oleum, expressed as 3H2SO4 5SO3, is approximately 80.68%.