Final answer:
To find the number of moles of iron from a given mass, divide the mass by iron's molar mass (55.85 g/mol), resulting in approximately 1.46 moles for 81.4 g of iron.
Step-by-step explanation:
To calculate the number of moles of iron from the given mass, you need to use the molar mass of iron from the periodic table. Since the molar mass of iron is 55.85 g/mol, you can divide the mass of the iron by this molar mass to find the number of moles.
Number of moles = Mass of iron (g) / Molar mass of iron (g/mol).
In this case: Number of moles = 81.4 g / 55.85 g/mol = 1.46 moles.
Therefore, 81.4 g of iron corresponds to approximately 1.46 moles of iron. This calculation assumes that the mass is given to three significant figures due to it being more than 81 g but less than 82 g hence your final answer should be expressed to the same number of significant figures.