Sure! Let's calculate the molar masses of the given compounds step by step using the atomic masses from the periodic table.
### 1. Ammonia (NH₃)
To calculate the molar mass of ammonia (NH₃), we need to sum the atomic masses of 1 nitrogen (N) atom and 3 hydrogen (H) atoms.
- Atomic mass of nitrogen (N): 14.01 g/mol
- Atomic mass of hydrogen (H): 1.01 g/mol
The molar mass of NH₃ is:
[tex]\[ \text{Molar mass of NH}_3 = 1 \times (\text{atomic mass of N}) + 3 \times (\text{atomic mass of H}) \][/tex]
[tex]\[ \text{Molar mass of NH}_3 = 1 \times 14.01 + 3 \times 1.01 \][/tex]
[tex]\[ \text{Molar mass of NH}_3 = 14.01 + 3.03 \][/tex]
[tex]\[ \text{Molar mass of NH}_3 = 17.04 \][/tex]
Thus, the molar mass of ammonia (NH₃) is 17.04 g/mol.
### 2. Magnesium hydroxide (Mg(OH)₂)
To calculate the molar mass of magnesium hydroxide (Mg(OH)₂), we need to sum the atomic masses of 1 magnesium (Mg) atom, 2 oxygen (O) atoms, and 2 hydrogen (H) atoms.
- Atomic mass of magnesium (Mg): 24.31 g/mol
- Atomic mass of oxygen (O): 16.00 g/mol
- Atomic mass of hydrogen (H): 1.01 g/mol
The molar mass of Mg(OH)₂ is:
[tex]\[ \text{Molar mass of Mg(OH)}_2 = 1 \times (\text{atomic mass of Mg}) + 2 \times (\text{atomic mass of O} + \text{atomic mass of H}) \][/tex]
[tex]\[ \text{Molar mass of Mg(OH)}_2 = 1 \times 24.31 + 2 \times (16.00 + 1.01) \][/tex]
[tex]\[ \text{Molar mass of Mg(OH)}_2 = 24.31 + 2 \times 17.01 \][/tex]
[tex]\[ \text{Molar mass of Mg(OH)}_2 = 24.31 + 34.02 \][/tex]
[tex]\[ \text{Molar mass of Mg(OH)}_2 = 58.33 \][/tex]
Thus, the molar mass of magnesium hydroxide (Mg(OH)₂) is 58.33 g/mol.
### 3. Iron(III) oxide (Fe₂O₃)
To calculate the molar mass of iron(III) oxide (Fe₂O₃), we need to sum the atomic masses of 2 iron (Fe) atoms and 3 oxygen (O) atoms.
- Atomic mass of iron (Fe): 55.85 g/mol
- Atomic mass of oxygen (O): 16.00 g/mol
The molar mass of Fe₂O₃ is:
[tex]\[ \text{Molar mass of Fe}_2\text{O}_3 = 2 \times (\text{atomic mass of Fe}) + 3 \times (\text{atomic mass of O}) \][/tex]
[tex]\[ \text{Molar mass of Fe}_2\text{O}_3 = 2 \times 55.85 + 3 \times 16.00 \][/tex]
[tex]\[ \text{Molar mass of Fe}_2\text{O}_3 = 111.70 + 48.00 \][/tex]
[tex]\[ \text{Molar mass of Fe}_2\text{O}_3 = 159.70 \][/tex]
Thus, the molar mass of iron(III) oxide (Fe₂O₃) is 159.70 g/mol.
### Summary
- Ammonia (NH₃): 17.04 g/mol
- Magnesium hydroxide (Mg(OH)₂): 58.33 g/mol
- Iron(III) oxide (Fe₂O₃): 159.70 g/mol
