How many grams of oxygen gas are required

Question

According to the following reaction, how many grams of oxygen gas are required for the complete reaction of 31.1 grams of sulfur dioxide?

 

sulfur dioxide (g) + oxygen (g) sulfur trioxide (g)

 

_______grams oxygen gas

Answer 1

The balanced equation

 

               2 SO₂(g)   +   O₂(g)  ---------  SO₃(g)  

 

mol:         2 mol              1mol

 

gram:      2 x 64 g            1 x 32 g                           (convert the mol to gram using molar mass for SO₂ and O₂)

 

The amount of O2 required to completely react with SO2 can be calculated using the ratio from the above equation:

 

 

       1 x 32 g O2/(2 x 64g SO2)

 

Thus, for 31.1 g SO2

 

[1 x 32 g O2/(2 x 64g SO2)] x 31.1 g SO2  =   7. 78 g O2 is required.