Answer :

To determine the percent composition of sodium (Na) in the unknown compound, we follow these steps:

1. Identify the given mass of each component in the compound:
- Mass of sodium (Na): 14.19 grams
- Mass of oxygen (O): 19.76 grams
- Mass of chromium (Cr): 16.05 grams
- Total mass of the compound: 50.0 grams

2. Calculate the percent composition using the formula:
[tex]\[ \text{Percent composition of Na} = \left( \frac{\text{Mass of Na}}{\text{Total mass of the compound}} \right) \times 100 \][/tex]

3. Substitute the given values into the formula:
[tex]\[ \text{Percent composition of Na} = \left( \frac{14.19 \text{ grams}}{50.0 \text{ grams}} \right) \times 100 \][/tex]

4. Perform the division and multiplication to find the percent composition:
[tex]\[ \left( \frac{14.19}{50.0} \right) \times 100 = 28.38 \][/tex]

Hence, the percent composition of sodium (Na) in the compound is 28.38%.