Answer
Mass of mercury=498.33g
Work Step by Step
Molar mass mercury=200.59amu
The molar mass of mercury sulfide=232.66amu
First, we calculate the percent composition of mercury using the formula:
Percent composition of mercury=$\frac{\text{molar mass of mercury}}{Total molar mass}\times100=\frac{200.59}{232.66}\times100\approx86.216\%$
Then we calculate the mass of mercury in 578g HgS using the percent composition:
Mass of mercury=$Total mass\times \text{percent composition mercury}=578\times86.216\%\approx498.33g$
