A 12.8 g sample of iron ore is treated as follows. The iron in the sample is all converted by a series of chemical reactions to Fe2O3. The mass of Fe2O3 is measured to be 21.3 g. What was the mass of iron in the sample of ore?
Answer in units of g.
21.3 g Fe2O3 x (2*atomic mass Fe/molar mass Fe2O3)= ?
You don't need the mass of the sample of 12.8 grams. That would be needed only if you wanted % Fe in the sample.
To find the mass of iron in the sample of ore, you can use the information given about the mass of Fe2O3.
First, determine the molar mass of Fe2O3. The molar mass of Fe is 55.845 g/mol, and the molar mass of O is 16.00 g/mol. Since Fe2O3 has two Fe atoms, the molar mass of Fe2O3 is:
2(55.845 g/mol) + 3(16.00 g/mol) = 159.69 g/mol
Next, calculate the number of moles of Fe2O3 using its mass:
moles of Fe2O3 = mass of Fe2O3 / molar mass of Fe2O3
moles of Fe2O3 = 21.3 g / 159.69 g/mol
Now, since the chemical reaction converts all the iron in the sample to Fe2O3, the number of moles of Fe2O3 is equal to the number of moles of iron in the sample.
Finally, calculate the mass of iron using the number of moles of Fe2O3 and the molar mass of Fe:
mass of iron = moles of Fe2O3 * molar mass of Fe
mass of iron = moles of Fe2O3 * 55.845 g/mol
Substitute the value of moles of Fe2O3 calculated earlier into the equation to find the mass of iron in the sample of ore.