Answer :

To determine how many moles are in 98.3 grams of aluminum hydroxide, [tex]\( \text{Al(OH)}_3 \)[/tex], we start by calculating its molar mass. Here’s how you can do it step-by-step:

1. Identify the Atomic Masses:
- Aluminum (Al) has an atomic mass of approximately 26.98 g/mol.
- Oxygen (O) has an atomic mass of approximately 16.00 g/mol.
- Hydrogen (H) has an atomic mass of approximately 1.01 g/mol.

2. Calculate the Molar Mass of [tex]\( \text{Al(OH)}_3 \)[/tex]:
- The formula [tex]\( \text{Al(OH)}_3 \)[/tex] includes one aluminum atom, three oxygen atoms, and three hydrogen atoms.
- The molar mass calculation is as follows:
[tex]\[
\text{Molar mass of } \text{Al(OH)}_3 = 26.98 \, \text{(Al)} + 3 \times (16.00 \, \text{(O)} + 1.01 \, \text{(H)})
\][/tex]
- Simplifying this gives:
[tex]\[
\text{Molar mass of } \text{Al(OH)}_3 = 26.98 + 3 \times (16.00 + 1.01) = 26.98 + 3 \times 17.01 = 26.98 + 51.03 = 78.01 \, \text{g/mol}
\][/tex]

3. Calculate the Number of Moles:
- Given mass of [tex]\( \text{Al(OH)}_3 \)[/tex] is 98.3 grams.
- Use the formula for moles:
[tex]\[
\text{Number of moles} = \frac{\text{mass}}{\text{molar mass}}
\][/tex]
- So, the number of moles is:
[tex]\[
\text{Number of moles} = \frac{98.3}{78.01} \approx 1.26 \, \text{moles}
\][/tex]

Therefore, there are approximately 1.26 moles in 98.3 grams of [tex]\( \text{Al(OH)}_3 \)[/tex].

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