Question

How many liters of oxygen gas, at standard temperature and pressure, will react with 35.8 grams of iron metal?

Answer 1

Answer:

1) Chemical equation:

2Ca + O₂ → 2CaO

2) Mole ratios: 2 mol Ca : 1 mol O₂ : 2 mol CaO

3) Convert 35.4 g of Ca to moles:

n = mass in grams / molar mass = 35.4 g / 40.1 g/mol = 0.883 mol

4) Volume proportion: 1 mol of gas at STP = 22.4 l

1 mol at STP              0.883 mol at

22.4 l                                      x

⇒ x = 0.883 mol × 22.4 l / 1 mol = 19.8 l ← answer