You calculate the mass of a water molecule by adding the atomic weights of its constituent atoms, two hydrogen atoms and one oxygen atom, using the periodic table of the elements.
Understanding the Composition of Water
Water, a fundamental substance for life, is composed of two elements:
- Hydrogen (H)
- Oxygen (O)
Each water molecule consists of two hydrogen atoms and one oxygen atom, hence the chemical formula H2O.
Calculating the Molecular Mass
To find the mass of a water molecule, follow these steps:
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Determine the Atomic Weights:
- Hydrogen has an atomic weight of approximately 1 gram/mole.
- Oxygen has an atomic weight of approximately 16 grams/mole.
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Calculate the Combined Weight:
Since a water molecule has two hydrogen atoms and one oxygen atom, the calculation is as follows:
Element Atomic Weight (grams/mole) Number of Atoms Total Weight (grams/mole) Hydrogen 1 2 2 Oxygen 16 1 16 Total 18 The molecular weight of one water molecule is the sum of the atomic weights:
2(1) + 1(16) = 18 grams/mole
Practical Implications
Understanding the molecular mass of water is crucial in various scientific fields:
- Chemistry: For stoichiometry calculations in chemical reactions.
- Biology: To understand the properties of water in biological systems.
- Environmental Science: To analyze water quality and behavior in ecosystems.
