Zinc metal reacts with yellow crystals of sulfur in a fiery reaction to produce a white powder of zinc sulfide. A chemist determines that 65.4 g of zinc reacts with 32.1 g of sulfur. How many grams of zinc sulfide could be produced from 20.0 g of zinc metal?
Solution:
We can use the law of conservation of mass to figure out how many grams of zinc sulfide could be produced. We can write the following:
Mass of zinc + mass of sulfur = mass of zinc sulfide
Thus, we can write:
m_{ZnS}=65.4g+32.1g
m_{ZnS}= 97.5g
To figure out how many grams of zinc sulfide could be produced from 20.0 g of zinc metal, we can say that:
20.0 g + mass of sulfur = x (where x is the mass of zinc sulfide that can be produced)
Using proportions, we can write:
\frac{m_{Zn}}{m_{ZnS}}=\frac{65.4 g}{97.5 g}=\frac{20.0g}{x}
x=29.81g