A 33.8 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 20.7 g.
What was the mass of iron in the sample of
ore?
Answer in units of g.

- I Don't Even Know Where To Start With This.

It's just a matter of converting the mass of one material to another.

mm stands for molar mass and am stands for atomic mass.

You want to convert 20.7 g Fe2O3 to mass Fe initially. How many mols Fe2O3 do you have?
mols Fe2O3 = grams Fe2O3/mm Fe2O3 = ?.

mols Fe = ? x (2 mol Fe/1 mol Fe2O3) = ?

g Fe = mols Fe x am Fe.

mols Fe2O3= 20.7/159.7= 0.1296

mols Fe= 0.1296x2= 0.2592
g Fe= 0.2592x55.85 = 14.478334

? Thanks a bunch.

That looks ok to me but you have too many digits in your answer. The 20.7 number limits the number of significant digits to three, therefore, your answered should be rounded to 14.5 g Fe.

To find the mass of iron in the sample of ore, you can use the information given about the conversion of iron to Fe2O3 (iron oxide).

1. Convert the mass of Fe2O3 to moles:
First, calculate the number of moles of Fe2O3 using its molar mass. The molar mass of Fe2O3 is 159.69 g/mol (2 * atomic mass of Fe + 3 * atomic mass of O).

Number of moles of Fe2O3 = Mass of Fe2O3 / Molar mass of Fe2O3
Number of moles of Fe2O3 = 20.7 g / 159.69 g/mol

2. Determine the number of moles of iron (Fe) involved in the reaction:
Since Fe2O3 is formed from iron (Fe), the ratio of moles of Fe to moles of Fe2O3 is 2:1. Therefore, the number of moles of iron (Fe) is half the number of moles of Fe2O3.

Number of moles of Fe = (1/2) * Number of moles of Fe2O3

3. Convert the moles of iron (Fe) to mass:
To find the mass of iron (Fe), multiply the number of moles of Fe by the molar mass of iron (55.85 g/mol).

Mass of Fe = Number of moles of Fe * Molar mass of Fe

Now you can plug in the numbers and calculate the mass of iron in the sample of ore.