Physical changes can be reversed and chemical changes can’t be reversed. A physical property is a characteristic which can be identified without changing the substance but to identify a chemical property, you do have to change the substance.
You are given
300 grams of FeCr2O7. You are required to get the mass of O2 in grams. The first
thing to do is to find a reaction between FeCr2O7 and O2. The balanced chemical
reaction is 2Fe + 6Cr + 21/2O2 -> Fe2(Cr2O7)3. The molar mass of Fe2(Cr2O7)3
is 759.65 grams per mole and 32 grams per mole for O2.
<span>
300g Fe2(Cr2O7)3
(1 mol Fe2(Cr2O7)3/759.65 g Fe2(Cr2O7)3)(21/2 mol O2/1 mole Fe2(Cr2O7)3)(32 g
O2/1 mole O2) = <u>132.7 g O2</u></span>
Yes they do. they work very hard for their nitrogen.
