What is the molar mass of AlCl3?
The correct answer and explanation is:
Correct Answer:
The molar mass of AlCl₃ (Aluminum chloride) is 133.33 g/mol.
Explanation:
To calculate the molar mass of a compound, sum the atomic masses of all the atoms present in the formula. The atomic masses used are taken from the periodic table and expressed in grams per mole (g/mol).
AlCl₃ contains:
- 1 atom of Aluminum (Al)
- 3 atoms of Chlorine (Cl)
From the periodic table:
- The atomic mass of Aluminum (Al) is 26.98 g/mol
- The atomic mass of Chlorine (Cl) is 35.45 g/mol
Now calculate: Molar mass of AlCl3=(1×26.98)+(3×35.45)\text{Molar mass of AlCl}_3 = (1 \times 26.98) + (3 \times 35.45) =26.98+106.35=133.33 g/mol= 26.98 + 106.35 = 133.33 \, \text{g/mol}
This value represents the mass of one mole of aluminum chloride molecules. Molar mass is important in chemistry because it allows conversion between grams and moles of a substance, which is critical for quantitative chemical calculations.
For instance, if someone has 10 grams of AlCl₃ and wants to know how many moles that is, they would divide the mass by the molar mass: Moles of AlCl3=10 g133.33 g/mol≈0.075 mol\text{Moles of AlCl}_3 = \frac{10 \, \text{g}}{133.33 \, \text{g/mol}} \approx 0.075 \, \text{mol}
This is useful in stoichiometry, where balanced chemical equations help determine the proportions of reactants and products. The molar mass of AlCl₃ also helps in preparing solutions of known concentration and in analyzing chemical reactions that involve aluminum chloride.
Understanding molar mass is a foundation in chemistry because it bridges the microscopic world of atoms and molecules with the measurable quantities used in laboratories.