Use the reaction shown to calculate the mass of iron that must be used to obtain 0.500 L of hydrogen at STP: 3Fe(s) + 4H2O(l) pr029-1.jpg Fe3O4(s) + 4H2(g
To calculate the mass of iron required to produce 0.500 L of hydrogen at STP (Standard Temperature and Pressure), we need to follow these steps:
1. Determine the balanced chemical equation:
3Fe(s) + 4H2O(l) -> Fe3O4(s) + 4H2(g)
2. Find the molar ratio between iron (Fe) and hydrogen (H2) in the balanced equation. In this case, the molar ratio is 3:4, which means that 3 moles of Fe react to produce 4 moles of H2.
3. Use the Ideal Gas Law to calculate the number of moles of hydrogen. At STP, 1 mole of any ideal gas occupies a volume of 22.4 liters. Thus, 0.500 L of H2 at STP is equal to:
(0.500 L) / (22.4 L/mol) = 0.0223 moles of H2
4. Set up a ratio using the molar ratio obtained from the balanced equation. Since the molar ratio of Fe to H2 is 3:4, we can set up the following proportion:
(0.0223 moles H2 / 4 moles H2) = (x moles Fe / 3 moles Fe)
5. Solve for x (the number of moles of Fe) by cross-multiplying and dividing:
x moles Fe = (0.0223 moles H2 * 3 moles Fe) / 4 moles H2
x moles Fe = 0.0167 moles Fe
6. Convert moles of iron to grams. The molar mass of iron (Fe) is approximately 55.85 g/mol. Therefore:
Mass of Fe = (0.0167 moles Fe) * (55.85 g/mol)
Mass of Fe = 0.9316 g
Therefore, approximately 0.9316 grams of iron must be used to obtain 0.500 L of hydrogen at STP.
mols H2 needed = 0.500L/22.4L = ? at STP.
mols Fe needed = 3/4 that (see the coefficients in the balanced equation.)
g Fe = mols x atomic mass.