The atomic mass of Cl is 35.45 amu, and the atomic mass of Al is 26.98 amu. What are the masses in grams of 3 mol of Al atoms and of 2 mol of Cl atoms?
The correct answer and explanation is :
To find the masses in grams of 3 mol of aluminum (Al) atoms and 2 mol of chlorine (Cl) atoms, we can use the relationship between moles, atomic mass, and mass:
[
\text{Mass} = \text{moles} \times \text{atomic mass}
]
Step 1: Calculate the mass of 3 mol of Al atoms
The atomic mass of aluminum (Al) is given as 26.98 amu. This value tells us that 1 mole of Al atoms has a mass of 26.98 grams. Therefore, to find the mass of 3 moles of Al atoms, we use the following formula:
[
\text{Mass of Al} = 3 \, \text{mol} \times 26.98 \, \text{g/mol}
]
[
\text{Mass of Al} = 80.94 \, \text{grams}
]
So, 3 moles of Al atoms have a mass of 80.94 grams.
Step 2: Calculate the mass of 2 mol of Cl atoms
The atomic mass of chlorine (Cl) is given as 35.45 amu. This means that 1 mole of Cl atoms has a mass of 35.45 grams. To find the mass of 2 moles of Cl atoms, we apply the same formula:
[
\text{Mass of Cl} = 2 \, \text{mol} \times 35.45 \, \text{g/mol}
]
[
\text{Mass of Cl} = 70.90 \, \text{grams}
]
So, 2 moles of Cl atoms have a mass of 70.90 grams.
Explanation
The calculation of the mass of a substance is based on the concept of the mole, which is the amount of substance containing as many particles as there are atoms in 12 grams of carbon-12. The atomic mass (measured in atomic mass units, amu) represents the mass of one atom of an element, and it can be converted to grams per mole for use in calculations. When you multiply the number of moles by the atomic mass (in grams per mole), you get the total mass in grams.
Thus, for aluminum and chlorine, we use their respective atomic masses (26.98 g/mol and 35.45 g/mol) and multiply by the number of moles (3 mol for Al and 2 mol for Cl) to find the total mass. This method allows us to convert from moles to mass easily.
