How many moles are in 98.3 grams of aluminum hydroxide, Al(OH)
3
?
The Correct Answer and Explanation is :
The correct answer is: 1.26 moles
To determine how many moles are in 98.3 grams of aluminum hydroxide (Al(OH)₃), we need to use the formula:
[
\text{Number of moles} = \frac{\text{mass (g)}}{\text{molar mass (g/mol)}}
]
Step 1: Calculate the Molar Mass of Aluminum Hydroxide
Aluminum hydroxide has the chemical formula Al(OH)₃. To find its molar mass, we need to sum the molar masses of all the atoms in the formula:
- Aluminum (Al): The molar mass of aluminum is approximately 26.98 g/mol.
- Oxygen (O): The molar mass of oxygen is approximately 16.00 g/mol. Since there are three hydroxide (OH) groups, we have three oxygen atoms contributing to the molar mass:
[ 3 \times 16.00 \, \text{g/mol} = 48.00 \, \text{g/mol} ] - Hydrogen (H): The molar mass of hydrogen is approximately 1.01 g/mol. Again, since there are three hydroxide groups, we have three hydrogen atoms:
[ 3 \times 1.01 \, \text{g/mol} = 3.03 \, \text{g/mol} ]
Adding these together gives us the molar mass of aluminum hydroxide:
[
\text{Molar mass of Al(OH)₃} = 26.98 \, \text{g/mol} + 48.00 \, \text{g/mol} + 3.03 \, \text{g/mol} = 78.01 \, \text{g/mol}
]
Step 2: Calculate the Number of Moles
Now, we can calculate the number of moles of aluminum hydroxide in 98.3 grams:
[
\text{Number of moles} = \frac{98.3 \, \text{g}}{78.01 \, \text{g/mol}} \approx 1.26 \, \text{moles}
]
Conclusion
Thus, there are approximately 1.26 moles of aluminum hydroxide in 98.3 grams. Understanding the concept of moles and molar mass is fundamental in chemistry, as it allows scientists to relate the mass of a substance to the number of particles it contains, facilitating calculations in chemical reactions, stoichiometry, and various applications in fields like biochemistry and materials science.