MCQ Detailed View

Ammonia (NH₃) is a simple nitrogen-containing compound widely used in fertilizers, cleaning products, and chemical synthesis. Its molecular formula consists of 1 nitrogen (N) atom and 3 hydrogen (H) atoms. The molecular weight (or molar mass) of a compound is calculated by summing the atomic masses of all its constituent atoms.

Using standard atomic masses:

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  Hydrogen (H) = 1.008 g/mol

  
  


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  Nitrogen (N) = 14.007 g/mol

  
  

The molecular weight of NH₃ is calculated as follows:

$$\text{Molecular weight}=(1\times 14.007)+(3\times 1.008)$$ $$=14.007+3.024$$ $$=17.031\text{g/mol}$$

Other options are incorrect:

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  18.031 g/mol, 19.031 g/mol, and 27.033 g/mol do not match the sum of the atomic masses of NH₃.

  
  

The molecular weight is essential for stoichiometric calculations, preparing solutions, and determining gas quantities in chemical reactions. For instance, knowing that one mole of ammonia weighs 17.031 grams allows chemists to calculate moles from mass and vice versa.

Ammonia is also a basic molecule in inorganic chemistry, forming compounds like ammonium salts and complexes with transition metals. Understanding its molecular weight helps in reaction balancing, concentration calculations, and laboratory preparations.

In summary, the molecular weight of ammonia (NH₃) is 17.031 g/mol, and this fundamental knowledge is crucial for students, chemists, and industry professionals in performing accurate chemical calculations.