Chapter 2, Problem 81PS

### Chemistry & Chemical Reactivity

10th Edition
John C. Kotz + 3 others
ISBN: 9781337399074

Chapter
Section

### Chemistry & Chemical Reactivity

10th Edition
John C. Kotz + 3 others
ISBN: 9781337399074
Textbook Problem

# Calculate the mass percent of copper in CuS, copper(II) sulfide. If you wish to obtain 10.0 g of copper metal from copper(II) sulfide, what mass of CuS (in grams) must you use?

Interpretation Introduction

Interpretation:

The mass percent of copper in CuS and the mass of CuS required to obtain 10g of copper metal are needed to be calculated.

Concept introduction:

• Mass percent of elements of a compound is the ratio of mass of element to the mass of whole compound and multiplied with hundred.
• Equation for finding molar mass from mass of a molecule and number moles is,

Molarmass=MassingramsNumberofmoles

• Molar mass of a molecule can be calculated from its molecular formula by taking the sum of atomic masses of all the elements present in it.
Explanation

The molecule CuS contains 1CuÂ andÂ 1S Â atoms, so the molar mass of the compound can be written as,

1Ã—63.546g/molâ€‰(Cu)+1Ã—32.06g/molâ€‰(S)â€‰=â€‰â€‰95.606g/molâ€‰(CuS)

Mass percent of elements of a compound is the ratio of mass of element to the mass of whole compound and multiplied with hundred.

Therefore,

The mass percent of copper in CuS is,

Â Â Â Â Â Â Â Â 63.546g95.606gâ€‰Ã—100%â€‰=â€‰66

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