Answer:
m = 16.67 g of Hg
Step-by-step explanation:
Let's write the overall decomposition reaction that is taking place:
2HgO ---------> 2Hg + O₂
According to the balanced reaction, we can see that the mole ratio between HgO and Hg is the same (2:2 or 1:1), therefore, we can assume that the moles reactants of HgO would be the moles produced of Hg. So, in order to get the grams of mercury, we need to determine the moles first.
To get the moles, we need to use the following expression:
moles = mass / MM (1)
The molar mass of HgO can be calculated using the atomic weights, which are:
Hg: 200.59 g/mol ; O: 15.999 g/mol
MM HgO = 200.59 + 15.999 = 216.589 g/mol
The moles are:
moles HgO = 18 / 216.589 = 0.0831 moles
As we stated before, moles reactants are the same moles produced, so:
moles HgO = moles Hg = 0.0831 moles of Hg.
Finally, to get the mass, we just solve the mass from (1):
m = moles * MM (2)
m = 0.0831 * 200.59
m = 16.67 g of Hg
Hope this helps