Calculate the molar mass of acetylsalicylic acid, the active ingredient in aspirin. The molecular formula for acetylsalicylic acid..
The Correct Answer and Explanation is:
Acetylsalicylic acid (ASA), the active ingredient in aspirin, has the molecular formula C₉H₈O₄. To calculate its molar mass, we need to sum the molar masses of all the atoms in its molecular formula.
- Identify the elements and their molar masses:
- Carbon (C) has an atomic mass of 12.01 g/mol.
- Hydrogen (H) has an atomic mass of 1.008 g/mol.
- Oxygen (O) has an atomic mass of 16.00 g/mol.
- Count the number of atoms of each element in the molecular formula C₉H₈O₄:
- 9 Carbon atoms (C)
- 8 Hydrogen atoms (H)
- 4 Oxygen atoms (O)
- Multiply the number of atoms by their atomic masses and then sum the results:
- For carbon: 9 atoms × 12.01 g/mol = 108.09 g/mol
- For hydrogen: 8 atoms × 1.008 g/mol = 8.064 g/mol
- For oxygen: 4 atoms × 16.00 g/mol = 64.00 g/mol
- Add the masses of all elements:
[
\text{Molar mass of acetylsalicylic acid} = 108.09 \, \text{g/mol} + 8.064 \, \text{g/mol} + 64.00 \, \text{g/mol} = 180.154 \, \text{g/mol}
]
Therefore, the molar mass of acetylsalicylic acid (aspirin) is 180.154 g/mol.
Explanation:
The molar mass of a compound is calculated by adding the individual molar masses of each atom that makes up the compound, based on its molecular formula. In the case of acetylsalicylic acid, each atom (carbon, hydrogen, and oxygen) has a known atomic mass, which is listed on the periodic table. These atomic masses are multiplied by the number of atoms of each element present in the compound.
Acetylsalicylic acid is commonly used in medicine as an analgesic, anti-inflammatory, and antipyretic, and knowing its molar mass is important for determining the dosage and concentration in pharmaceutical preparations. This knowledge allows for accurate formulation and precise administration of aspirin in clinical settings.