Skip to main content
Ch.3 - Chemical Reactions and Reaction Stoichiometry
Chapter 3, Problem 60

Epsom salts, a strong laxative used in veterinary medicine, is a hydrate, which means that a certain number of water molecules are included in the solid structure. The formula for Epsom salts can be written as MgSO4 # xH2O, where x indicates the number of moles of H2O per mole of MgSO4. When 5.061 g of this hydrate is heated to 250 C, all the water of hydration is lost, leaving 2.472 g of MgSO4. What is the value of x?

Verified Solution

Video duration:
1m
This video solution was recommended by our tutors as helpful for the problem above.
Was this helpful?

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Hydrates

Hydrates are compounds that contain water molecules within their crystalline structure. The general formula for a hydrate is represented as AB·xH2O, where AB is the anhydrous compound and x indicates the number of water molecules associated with each formula unit. Understanding hydrates is crucial for determining the composition and behavior of these compounds when subjected to heat or other conditions.
Recommended video:
Guided course
02:04
Ionic Hydrates Naming

Molar Mass and Mass Loss

Molar mass is the mass of one mole of a substance, typically expressed in grams per mole. In the context of hydrates, when heated, the water of hydration is lost, resulting in a decrease in mass. By calculating the difference in mass before and after heating, one can determine the mass of water lost, which is essential for finding the value of x in the hydrate formula.
Recommended video:
Guided course
02:11
Molar Mass Concept

Stoichiometry

Stoichiometry is the area of chemistry that deals with the quantitative relationships between reactants and products in a chemical reaction. It allows chemists to calculate the amounts of substances involved based on their molar ratios. In this problem, stoichiometry is used to relate the mass of the anhydrous salt to the mass of water lost, facilitating the determination of the number of water molecules per formula unit of the hydrate.
Recommended video:
Guided course
01:16
Stoichiometry Concept
Related Practice
Textbook Question

Valproic acid, used to treat seizures and bipolar disorder, is composed of C, H, and O. A 0.165-g sample is combusted to produce 0.166 g of water and 0.403 g of carbon dioxide. What is the empirical formula for valproic acid?

919
views
Textbook Question

Propenoic acid, C3H4O2, is a reactive organic liquid that is used in the manufacturing of plastics, coatings, and adhesives. An unlabeled container is thought to contain this liquid. A 0.275-g sample of the liquid is combusted to produce 0.102 g of water and 0.374 g carbon dioxide. Is the unknown liquid propenoic acid? Support your reasoning with calculations.

2291
views
Textbook Question

Washing soda, a compound used to prepare hard water for washing laundry, is a hydrate, which means that a certain number of water molecules are included in the solid structure. Its formula can be written as Na2CO3 # xH2O, where x is the number of moles of H2O per mole of Na2CO3. When a 2.558-g sample of washing soda is heated at 125 C, all the water of hydration is lost, leaving 0.948 g of Na2CO3. What is the value of x?

2993
views
1
comments
Textbook Question

Hydrofluoric acid, HF(aq), cannot be stored in glass bottles because compounds called silicates in the glass are attacked by the HF(aq). Sodium silicate 1Na2SiO32, for example, reacts as follows: Na2SiO31s2 + 8 HF1aq2¡ H2SiF61aq2 + 2 NaF1aq2 + 3 H2O1l2 (b) How many grams of NaF form when 0.500 mol of HF reacts with excess Na2SiO3?

5329
views
Textbook Question

The reaction between potassium superoxide, KO2, and CO2, 4 KO2 + 2 CO2¡2K2CO3 + 3 O2 is used as a source of O2 and absorber of CO2 in selfcontained breathing equipment used by rescue workers. (a) How many moles of O2 are produced when 0.400 mol of KO2 reacts in this fashion?

1945
views
Textbook Question

The reaction between potassium superoxide, KO2, and CO2, 4 KO2 + 2 CO2¡2K2CO3 + 3 O2 is used as a source of O2 and absorber of CO2 in selfcontained breathing equipment used by rescue workers. (b) How many grams of KO2 are needed to form 7.50 g of O2?

678
views