Problem 69 - Chemistry The Molecular Nature of Matter

Question

Epsom salts is a hydrate of magnesium sulfate, \(\mathrm{MgSO}_{4} \cdot 7 \mathrm{H}_{2} \mathrm{O} .\) What is the formula of the substance that remains when Epsom salts is completely dehydrated?

Step-by-Step Solution

Answer

The formula for the substance remaining after completely dehydrating Epsom salts is \(\mathrm{MgSO}_{4}\).

Step 1: Understanding Epsom Salts Composition

Epsom salts is a compound which includes both magnesium sulfate and water molecules. The given formula, \(\mathrm{MgSO}_{4} \cdot 7\mathrm{H}_{2}O\), shows that each formula unit contains one magnesium sulfate unit along with seven water molecules.

Step 2: Complete Dehydration of Epsom Salts

When Epsom salts is completely dehydrated, it means that all the water molecules are removed from the compound. In this case, seven water molecules will be removed from each formula unit of magnesium sulfate.

Step 3: Determining the Anhydrous Substance Formula

After the removal of the seven water molecules during the dehydration process, the anhydrous substance left is magnesium sulfate, which is represented by the chemical formula \(\mathrm{MgSO}_{4}\).

Key Concepts

Epsom Salts

Epsom salts, also known scientifically as magnesium sulfate heptahydrate, are a chemical compound that is known for its therapeutic properties and is commonly used in baths to relieve muscle aches. The 'heptahydrate' part of its name refers to the seven molecules of water ((H₂O)) that are chemically bonded to each magnesium sulfate molecule in its crystalline structure. This natural mineral has the formula (MgSO₄ · 7H₂O) and profoundly contributes to the drawing out of toxins from the body and to ease discomfort. In addition to health benefits, Epsom salts are also used agriculturally to replenish magnesium and sulfur in gardening soils.

It's essential for students to comprehend that dehydration of Epsom salts involves the removal of water, resulting in a chemical change that leads to an anhydrous form of magnesium sulfate, which has different properties to its hydrated counterpart.

Anhydrous Substance

An anhydrous substance is one that has had all water removed from its structure. The term 'anhydrous' literally means 'without water.' This is essential in various chemical processes and industries, as the presence of water can greatly affect the properties and behavior of the substance. When hydrates, like Epsom salts, undergo dehydration, the resultant matter loses its associated water molecules and becomes anhydrous.

Anhydrous magnesium sulfate, for instance, is more concentrated and has different applications compared to its hydrated form. It is important for students to recognize that during the dehydration process, the chemical composition of the substance is altered, although the fundamental identity of the primary compound, in this case, magnesium sulfate, remains unchanged.

Chemical Formula

Representation of a Compound

Understanding the chemical formula is fundamental in chemistry as it conveys crucial information about the composition of a compound. For Epsom salts, the chemical formula (MgSO₄ · 7H₂O) illustrates that for every molecule of magnesium sulfate, there are seven molecules of water associated with it. This ratio is critical when considering the transformation that occurs during the dehydration process.

Significance in Dehydration

The importance is two-fold here, students need to recognize that in the dehydrated state, the compound's formula changes to represent the removal of water molecules. Hence, the chemical formula serves as a blueprint of the substance's structure and is pivotal in predicting the results of chemical reactions, such as when determining what remains after fully dehydrating Epsom salts.

Magnesium Sulfate

Magnesium sulfate, denoted (MgSO₄), is a chemical substance that is incredibly versatile and serves a wide range of uses. It is present in the hydrated form in Epsom salts but also exists in an anhydrous state, which means without water. As an anhydrous compound, magnesium sulfate has applications across various industries including in agriculture as a soil additive, in medicine as a treatment for certain health conditions, and in science for laboratory experiments.

It is crucial for students to understand the versatility and practical uses of magnesium sulfate in both its hydrated and anhydrous forms. The transition from MgSO₄ · 7H₂O to MgSO₄ after dehydration is not merely a loss of water but also transforms the applications and physical properties of the substance.