Final answer:
To completely combust and produce 2.1 g of water, you would need 1.86 g of oxygen.
Step-by-step explanation:
To find the amount of oxygen needed to produce 2.1 g of water, we need to calculate the molar mass of water and use stoichiometry. The molar mass of water (H₂O) is 18.02 g/mol. From the balanced equation, we know that 1 mole of oxygen (O₂) reacts with 2 moles of water, so we can set up the following ratio:
1 mol O₂ : 2 mol H₂O
We know the mass of water produced is 2.1 g, so we can convert this to moles using the molar mass:
2.1 g H₂O x (1 mol H₂O / 18.02 g H₂O) = 0.116 mol H₂O
Using the mole ratio, we can now find the moles of oxygen needed:
0.116 mol H₂O x (1 mol O₂ / 2 mol H₂O) = 0.058 mol O₂
Finally, convert the moles of oxygen to grams using the molar mass:
0.058 mol O₂ x (32.0 g O₂ / 1 mol O₂) = 1.86 g O₂