Chapter 2, Problem 159IL

### 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

# If Epsom salt, MgSO4 · x H2O, is heated to 250 °C, all the water of hydration is lost. On heating a 1.687-g sample of the hydrate, 0.824 g of MgSO4 remains. How many molecules of water occur per formula unit of MgSO4?

Interpretation Introduction

Interpretation: The number of water molecules per formula of MgSO4 has to be calculated from the given data’s of Epson salt.

Concept introduction:

• Conversion formula for mass of a molecule and number moles,

Numberofmoles=MassingramsMolarmass

• 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.
• Moles: One mole is equivalent to the mass of the substance consists same number of units equal to the atoms present in 12g of 12C.
• The mole is actually quantity of particles that is Avogadro’s number of particles present in elements or compounds.
• The sum of mass of all atoms present in formula of chemical substance is referred as molecular or formula weight of that substance.
• Mass: It is the quantitative measure of a substance. The amount of matter present in substance is expressed as mass. The S.I. unit of mass is kg.
Explanation

Given,

The mass of hydrated sample is 1.687g.

The mass of dehydrated sample is 0.824g.

Therefore,

The mass of water molecules in the sample is 1.687gâˆ’0.824g=â€‰0.863gÂ

Equation for finding number moles from mass of a molecule and molar mass is,

Â Â Â Â Numberâ€‰ofâ€‰molesâ€‰â€‰=â€‰â€‰Massâ€‰inâ€‰gramsâ€‰Molarâ€‰massÂ

Therefore,

The number of moles of water molecule is,

Â Â Â Â Numberâ€‰ofâ€‰molesâ€‰â€‰=â€‰â€‰0.863gâ€‰18gâ€‰â€‰=â€‰â€‰0

### Still sussing out bartleby?

Check out a sample textbook solution.

See a sample solution

#### The Solution to Your Study Problems

Bartleby provides explanations to thousands of textbook problems written by our experts, many with advanced degrees!

Get Started