Answer:
a) 8 grams
Explanation:
Ok, so you want to do these type of questions using dimensional analysis. It is quite confusing at first for new students, but essnetially its all fractions multiplying with each other, start with your numerator of a given value, and end with the numerator of what your trying to find, while canceling all the units to see if you truly have the unknown value left.
[tex]\frac{10.7g Fe(OH)_3}{1} *\frac{1 mol Fe(OH)_3}{107gFe(OH)_3} *\frac{1molFe_2O_3}{2molFe(OH)_3} *\frac{159.7gFe_2O_3}{1molFe_2O_3}[/tex]
So start with 10.7g Fe(OH)3 because that was the given unit, then you build up from down up down up, with each intention canceling the previous unit. So we have 10.7g, then we know FeOH3 is 107g/mol, so put 107g to bottom to cancel out the mass unit. You know that its 107g per mol so that 1 mol goes up. Now lets continue, try to cancel mol FeOH3, we know there is 2 FeOH3 moles in the reaction, so put it down. Now that everything about FeOH3 is gone, put everything about Fe2O3, so to have the mass of Fe2O3 on top, continue with how many moles in the reaction, then to cancel the moles, multiply by molar mass. Now we see all the units are canceled.
This gives you 7.985, so 8 grams. a)
