Question

Cinnabar(HgS) is a prominent ore of mercury. How many grams of mercury are present in 225g of pure HgS? Molar mass of Hg and S are 200. 6g mol-1 and 32 g mol-1 respectively.

Answer 1

So here mass of HgS given=225 gram.

Molecular mass of HgS is 200.6+32=232.6 gram.

Hence moles present in given mass=225/232.6=0.94 grams.

As you know in 1 mole of HgS there is one mole of Hg.

So in 0.94 moles of HgS there will be 0.94 moles of Hg.

As mass is asked we know mass=moles× molecular mass=0.94×200.6=194.04 gram.

So it exists 194.94 gram Hg in 225 gram HgS.

Thanks.
Tripathy

Answer 2

Answer:

Molar mass of HgS =200.6+32=232.6 gm mol

−1

Mass of Hg in 232.6 gms of HgS=200.6 gms

Mass of Hg in 225 gm of HgS =

232.6

200.6

×225=194.04g