5 moles.
think about the ratio of moles of iron oxide (Fe2O3) and iron (Fe) in that balanced chemical equation, which is 1:2, respectively. if there are 10 moles of Fe, you would divide that by 2 to get the number of moles of Fe2O3.
Answer:
a) The work done is 10.0777 kJ
b) The water's change in internal energy is -122.1973 kJ
Explanation:
Given data:
1 mol of liquid water
T₁ = temperature = 100.9°C
P = pressure = 1 atm
Endothermic reaction
T₂ = temperature = 100°C
1 mol of water vapor
VL = volume of liquid water = 18.8 mL = 0.0188 L
VG = volume of water vapor = 30.62 L
3.25 moles of liquid water vaporizes
Q = heat added to the system = -40.7 kJ
Questions: a) Calculate the work done on or by the system, W = ?
b) Calculate the water's change in internal energy, ΔU = ?
Heat for 3.25 moles:

The work done:

The change in internal energy:

Salutations!
What causes a substance to change states of matter?
Energy causes a substance to change states of matter. A matter needs energy to melt, evaporate, boil. Remember: Energy has a sudden change, but the temperature remains absolutely the same. An example of a change in energy is when ice is melting.
Hope I helped (:
Have a great day!
See , from the equation we can see that for forming two mole of H2O 2Mole of H2 has to react.
Mass of 2 Mole H2O is 18*2gm or 36gm.
So for forming 36 gm H2O 2×2 I.e. 4 gm H2 has to take part in reaction.
Therefore, to form 1 gm H2O 4÷36 gm of H2 has to take part.
So, for forming 47gm H2O (4÷36)×47 gm H2 has to take part
I.e. 5.22 gm of H2 has to take part
So, ans is 5.22 gm of hydrogen.
Hope it helps!!!