To determine the mass of 1.72 moles of sodium nitrate (NaNO₃), we need to follow a few steps involving the calculation of the molar mass of sodium nitrate and then the multiplication by the number of moles given. Let's break it down step-by-step.
### Step 1: Determine the Molar Mass of Sodium Nitrate (NaNO₃)
1. Identify the Atomic Masses from the Periodic Table:
- Sodium (Na): 22.99 g/mol
- Nitrogen (N): 14.01 g/mol
- Oxygen (O): 16.00 g/mol
2. Determine the Number of Each Atom in the Compound:
- Sodium nitrate (NaNO₃) consists of 1 sodium (Na), 1 nitrogen (N), and 3 oxygen (O) atoms.
3. Calculate the Molar Mass of Each Element in the Compound:
- Molar mass of Na: \(\( 1 \times 22.99 \)\) g/mol = 22.99 g/mol
- Molar mass of N: \(\( 1 \times 14.01 \)\) g/mol = 14.01 g/mol
- Molar mass of O: \(\( 3 \times 16.00 \)\) g/mol = 48.00 g/mol
4. Sum the Molar Masses to Get the Total Molar Mass of Sodium Nitrate:
\(\[
\text{Molar mass of NaNO₃} = 22.99 \, \text{g/mol} + 14.01 \, \text{g/mol} + 48.00 \, \text{g/mol} = 85.00 \, \text{g/mol}
\]\)
### Step 2: Calculate the Mass of 1.72 Moles of Sodium Nitrate
Given that:
- The molar mass (MM) of NaNO₃ is 85.00 g/mol
- The number of moles (n) of NaNO₃ is 1.72
1. Use the Formula:
\(\[
\text{Mass} = \text{Molar mass} \times \text{Number of moles}
\]\)
2. Substitute the Given Values:
\(\[
\text{Mass} = 85.00 \, \text{g/mol} \times 1.72 \, \text{mol}
\]\)
3. Calculate the Mass:
\(\[
\text{Mass} = 146.2 \, \text{g}
\]\)
Thus, the mass of 1.72 moles of sodium nitrate (NaNO₃) is \(\( 146.2 \)\) grams.
The correct answer is:
- Option C: 146 g.
