Answer :
To find out how many moles are in 98.3 grams of aluminum hydroxide, Al(OH)3, follow these steps:
1. Understand the Formula: The molar mass of a compound is the sum of the molar masses of all its elements. Aluminum hydroxide is Al(OH)3.
2. Calculate the Molar Mass:
- Aluminum (Al) has a molar mass of about 27.0 g/mol.
- Oxygen (O) has a molar mass of about 16.0 g/mol.
- Hydrogen (H) has a molar mass of about 1.0 g/mol.
Use these values to find the molar mass of Al(OH)3:
[tex]\[
\text{Molar mass of Al(OH)}_3 = 27.0 + (16.0 \times 3) + (1.0 \times 3) = 27.0 + 48.0 + 3.0 = 78.0 \, \text{g/mol}
\][/tex]
3. Use the Formula for Moles: The formula to calculate moles is:
[tex]\[
\text{moles} = \frac{\text{mass in grams}}{\text{molar mass in g/mol}}
\][/tex]
4. Substitute the Values:
- Mass = 98.3 grams
- Molar mass = 78.0 g/mol
[tex]\[
\text{moles Al(OH)}_3 = \frac{98.3}{78.0} \approx 1.26
\][/tex]
Therefore, there are approximately 1.26 moles of Al(OH)3 in 98.3 grams. The correct answer is 1.26 moles Al(OH)3.
1. Understand the Formula: The molar mass of a compound is the sum of the molar masses of all its elements. Aluminum hydroxide is Al(OH)3.
2. Calculate the Molar Mass:
- Aluminum (Al) has a molar mass of about 27.0 g/mol.
- Oxygen (O) has a molar mass of about 16.0 g/mol.
- Hydrogen (H) has a molar mass of about 1.0 g/mol.
Use these values to find the molar mass of Al(OH)3:
[tex]\[
\text{Molar mass of Al(OH)}_3 = 27.0 + (16.0 \times 3) + (1.0 \times 3) = 27.0 + 48.0 + 3.0 = 78.0 \, \text{g/mol}
\][/tex]
3. Use the Formula for Moles: The formula to calculate moles is:
[tex]\[
\text{moles} = \frac{\text{mass in grams}}{\text{molar mass in g/mol}}
\][/tex]
4. Substitute the Values:
- Mass = 98.3 grams
- Molar mass = 78.0 g/mol
[tex]\[
\text{moles Al(OH)}_3 = \frac{98.3}{78.0} \approx 1.26
\][/tex]
Therefore, there are approximately 1.26 moles of Al(OH)3 in 98.3 grams. The correct answer is 1.26 moles Al(OH)3.
