A rock sample contains only Sb2S3 and FeS. If 835g of the sample contains 11.2% antimony, what is the mass percent of the Sb2S3 in the sample? What is the mass percent of the sulfur in the sample?
So far, I have determined that 11.2% of an 835g sample is 93.52g Sb, the molar mass of FeS is 87.92 g/mol and the molar mass of Sb2S3 is 339.73 g/mol. I have no idea where to go from here.
pretend you have 100 g of the sample
Then, you have 11.2 grams Sb. That is
moles Sb=11.2/molemassSb.
But you know the compound is Sb2S3, which means there are 1/2 * moles Sb of Sb2S3 (reason, if you have ten moles SB, you can make 5 moles Sb2S3).
Now, you know the moles Sb2S3. That means you have a mass of Sb2S3 of molesSb2S3*molmassSb2S3. So the percent of antomony sulide is then that mass divided by 100grams.
The remaining mass is Ferrous Sulfide, and you can determine its percent by dividing by 100
To find the mass percent of Sb2S3 in the sample, you need to determine the mass of Sb2S3 and divide it by the total mass of the sample.
1. Calculate the mass of antimony (Sb) in the sample:
Mass of antimony (Sb) = 11.2% of 835g = 0.112 * 835g = 93.52g
2. Since Sb2S3 contains two atoms of antimony for every one Sb2S3 formula unit, calculate the molar mass of Sb2S3:
Molar mass of Sb2S3 = (2 * atomic mass of antimony) + (3 * atomic mass of sulfur)
= (2 * 121.76 g/mol) + (3 * 32.06 g/mol)
= 243.52 g/mol + 96.18 g/mol
= 339.70 g/mol (approximated to two decimal places)
3. Calculate the mass of Sb2S3 in the sample using the mass of antimony (Sb) and the molar mass of Sb2S3:
Mass of Sb2S3 = (mass of Sb * molar mass of Sb2S3) / molar mass of Sb
= (93.52g * 339.70 g/mol) / 121.76 g/mol
= 260.83g (rounded to the nearest hundredth)
4. Finally, calculate the mass percent of Sb2S3 in the sample by dividing the mass of Sb2S3 by the total mass of the sample:
Mass percent of Sb2S3 = (mass of Sb2S3 / total mass of sample) * 100%
= (260.83g / 835g) * 100%
= 31.2% (approximated to one decimal place)
To find the mass percent of sulfur (S) in the sample:
1. Calculate the mass of Sulfur in the sample:
Mass of sulfur (S) = Total mass of sample - Mass of antimony (Sb)
= 835g - 93.52g
= 741.48g (rounded to two decimal places)
2. Calculate the mass percent of sulfur in the sample by dividing the mass of sulfur by the total mass of the sample:
Mass percent of Sulfur = (mass of S / total mass of sample) * 100%
= (741.48g / 835g) * 100%
= 88.8% (rounded to one decimal place)