According to the equation, one mole of methane will completely react with two moles of oxygen gas. To calculate the number of grams of oxygen required to completely react with 4.00 grams of methane, we first need to know how many moles 4.00 grams of methane is:
Molar mass of methane
What is the mass of one mole of methane?
Molar mass of methane = (molar mass of carbon) + 4(molar mass of hydrogen)
molar mass of methane = (12.01 g/mol) + 4(1.01 g/mol)
molar mass of methane = 12.01 g/mol + 4.04 g/mol
molar mass of methane = 16.05 g/mol
Now that we know that the mass of 1 mole of methane is 16.05 grams, we can calculate the number of moles in 4.00 grams of methane:
Total number of moles of methane
Number of moles = (Mass) ÷ (Molar Weight)
Number of moles = (4.00 grams) ÷ (16.05 grams/mole)
Number of moles = 0.25 moles
Number of moles of oxygen gas needed
Since two moles of oxygen gas are required for every mole of methane, the total number of moles of oxygen needed are:
Number of moles of oxygen = 2 × (Number of moles of methane)
Number of moles of oxygen = 2 × (0.25 moles)
Number of moles of oxygen = 0.50 moles
Finally, what is the mass of 0.50 moles of oxygen? For that, we need to know the molar mass of oxygen gas. Remember, oxygen gas is a diatomic molecule:
Molar mass of oxygen gas
molar mass of oxygen gas = 2(molar mass of oxygen)
molar mass of oxygen gas = 2(16.0 g/mol)
molar mass of oxygen gas = 32.0 g/mol
If we need 0.50 moles of oxygen gas and one mole of oxygen gas has a mass of 32.0 grams, then the mass of 0.50 moles of oxygen gas is:
Mass of oxygen needed
Mass of 0.50 moles of oxygen gas = (Molar mass of oxygen gas) × (Number of moles of oxygen gas)
Mass of 0.50 moles of oxygen gas = (32.0 grams/mole) × (0.50 moles)
Mass of 0.50 moles of oxygen gas = 16.0 grams
16.0 grams of oxygen gas are needed to completely react 4.00 grams of methane.
Molar mass of methane
What is the mass of one mole of methane?
Molar mass of methane = (molar mass of carbon) + 4(molar mass of hydrogen)
molar mass of methane = (12.01 g/mol) + 4(1.01 g/mol)
molar mass of methane = 12.01 g/mol + 4.04 g/mol
molar mass of methane = 16.05 g/mol
Now that we know that the mass of 1 mole of methane is 16.05 grams, we can calculate the number of moles in 4.00 grams of methane:
Total number of moles of methane
Number of moles = (Mass) ÷ (Molar Weight)
Number of moles = (4.00 grams) ÷ (16.05 grams/mole)
Number of moles = 0.25 moles
Number of moles of oxygen gas needed
Since two moles of oxygen gas are required for every mole of methane, the total number of moles of oxygen needed are:
Number of moles of oxygen = 2 × (Number of moles of methane)
Number of moles of oxygen = 2 × (0.25 moles)
Number of moles of oxygen = 0.50 moles
Finally, what is the mass of 0.50 moles of oxygen? For that, we need to know the molar mass of oxygen gas. Remember, oxygen gas is a diatomic molecule:
Molar mass of oxygen gas
molar mass of oxygen gas = 2(molar mass of oxygen)
molar mass of oxygen gas = 2(16.0 g/mol)
molar mass of oxygen gas = 32.0 g/mol
If we need 0.50 moles of oxygen gas and one mole of oxygen gas has a mass of 32.0 grams, then the mass of 0.50 moles of oxygen gas is:
Mass of oxygen needed
Mass of 0.50 moles of oxygen gas = (Molar mass of oxygen gas) × (Number of moles of oxygen gas)
Mass of 0.50 moles of oxygen gas = (32.0 grams/mole) × (0.50 moles)
Mass of 0.50 moles of oxygen gas = 16.0 grams
16.0 grams of oxygen gas are needed to completely react 4.00 grams of methane.
