Answer:
The mass of the steel wool before burning can be calculated by finding the difference between the mass of the steel wool and the mass of the iron oxide produced.
If the mass of the iron oxide produced is 715 g, then the mass of the steel wool before burning was:
Mass of steel wool before burning = Mass of steel wool + Mass of iron oxide produced
Since the steel wool was entirely converted to iron oxide, we know that the mass of iron in the steel wool is equal to the mass of iron in the iron oxide produced. Since iron has an atomic mass of 56 g/mol, we can use this to find the mass of iron in the 715 g of iron oxide:
Number of moles of iron = mass of iron oxide produced / atomic mass of iron
Number of moles of iron = 715 g / 56 g/mol
Number of moles of iron = 12.77 mol
Since the mass of iron in the steel wool is the same as the mass of iron in the iron oxide produced, we can use the same number of moles of iron to find the mass of steel wool before burning:
Mass of steel wool before burning = Number of moles of iron x (atomic mass of iron / molar mass of steel wool)
The molar mass of steel wool is the sum of the atomic masses of its constituent elements (iron and carbon) multiplied by their respective stoichiometric coefficients:
Molar mass of steel wool = (atomic mass of iron x 1) + (atomic mass of carbon x 1)
Molar mass of steel wool = (56 g/mol x 1) + (12.01 g/mol x 1)
Molar mass of steel wool = 68.01 g/mol
Substituting the known values into the equation, we get:
Mass of steel wool before burning = 12.77 mol x (56 g/mol / 68.01 g/mol)
Mass of steel wool before burning = 10.49 mol
Therefore, the mass of the steel wool before burning was:
Mass of steel wool before burning = Mass of steel wool + Mass of iron oxide produced
Mass of steel wool before burning = 715 g + (10.49 mol x 68.01 g/mol)
Mass of steel wool before burning = 1,428 g (rounded to the nearest whole number)
Step-by-step explanation: