Zinc metal reacts with yellow crystals of sulfur


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

 

This question can be found in General Chemistry, 9th edition, chapter 1, question 1.39

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