The molar mass of calcium hydroxide, Ca(OH)₂, is 74.092 g/mol.
Understanding Molar Mass
Molar mass is a fundamental concept in chemistry, representing the mass of one mole of a chemical substance. A mole is a unit of measurement that contains exactly 6.022 × 10²³ constituent particles (atoms, molecules, ions, or formula units), a value known as Avogadro's number. For compounds, the molar mass is calculated by summing the average atomic masses of all the atoms present in its chemical formula.
Calculating the Molar Mass of Ca(OH)₂
To determine the molar mass of calcium hydroxide, Ca(OH)₂, we need to consider the atomic masses of each element and how many atoms of each element are present in one formula unit of the compound.
The formula Ca(OH)₂ indicates:
- One calcium (Ca) atom
- Two oxygen (O) atoms (due to the subscript '2' outside the parenthesis)
- Two hydrogen (H) atoms (due to the subscript '2' outside the parenthesis)
Let's break down the calculation using the approximate atomic masses of each element:
| Element | Atomic Mass (g/mol) | Number of Atoms | Total Mass (g/mol) |
|---|---|---|---|
| Calcium (Ca) | 40.078 | 1 | 40.078 |
| Oxygen (O) | 15.999 | 2 | 31.998 |
| Hydrogen (H) | 1.008 | 2 | 2.016 |
| Total (Ca(OH)₂) | 74.092 |
Summing these values provides the molar mass of calcium hydroxide:
Molar Mass of Ca(OH)₂ = (1 × Atomic Mass of Ca) + (2 × Atomic Mass of O) + (2 × Atomic Mass of H)
Molar Mass of Ca(OH)₂ = (1 × 40.078 g/mol) + (2 × 15.999 g/mol) + (2 × 1.008 g/mol)
Molar Mass of Ca(OH)₂ = 40.078 g/mol + 31.998 g/mol + 2.016 g/mol
Molar Mass of Ca(OH)₂ = 74.092 g/mol
This value is derived from precise atomic weights and represents the mass of one mole of calcium hydroxide molecules.
Applications of Calcium Hydroxide
Calcium hydroxide, also commonly known as slaked lime or hydrated lime, is an inorganic compound with a wide range of industrial and practical applications due to its alkaline nature and low cost.
Some key uses include:
- Water Treatment: It is used as a flocculant in water and wastewater treatment to remove impurities.
- Agriculture: Employed to neutralize acidic soils and improve soil structure.
- Construction: A vital component in mortar, plaster, and cement, contributing to their binding properties.
- Food Industry: Used in the preparation of various foods, such as corn tortillas (as cal) and in the refining of sugar.
- Chemical Industry: Serves as a strong base in various chemical processes, including the production of paper and as a pH regulator.
Understanding the molar mass of Ca(OH)₂ is crucial for accurate calculations in these applications, ensuring proper stoichiometry and material quantities.
