Answer:
The remaining mass of ethane is 3.19 grams
Explanation:
Step 1: Data given
Mass of ethane = 7.22 grams
Mass of oxygen = 15.0 grams
Molar mass ethane = 30.07 g/mol
Molar mass oxygen = 32.0 g/mol
Step 2: The balanced equation
2C2H6 + 7O2 → 4CO2 + 6H2O
Step 3: Calculate moles ethane
Moles ethane = 7.22 grams / 30.07 g/mol
Moles ethane = 0.240 moles
Step 4: Calculate moles oxygen
Moles oxygen = 15.0 grams / 32.0 g/mol
Moles oxygen = 0.46875 moles
Step 5: Calculate limiting reactant
For 2 moles ethane we need 7 moles oxygen to produce 4 moles CO2 and 6 moles H2O
Oxygen is the limiting reactant. It will completely be consumed (0.46875 moles). Ethane is in excess. There will react 0.46875 / 3.5 = 0.134 moles
There will remain 0.240 - 0.134 = 0.106 moles
Step 6: Calculate mass of remaining ethane
Mass ethane = 0.106 moles * 30.06 g/mol
Mass ethane = 3.19 grams
The remaining mass of ethane is 3.19 grams