How many molecules are present in 25 grams of NH_3?

• A. 1.47 × 10^{24} molecules
• B. 8.83 × 10^{23} molecules
• C. 3.53 × 10^{24} molecules
• D. 2.21 × 10^{23} molecules

Answer: (B)

Verified step by step guidance

1. First, determine the molar mass of ammonia (NH_3). Calculate it by adding the atomic masses of nitrogen (N) and hydrogen (H): \(\text{Molar mass of NH}_3 = 14.01\,\text{g/mol} + 3 \times 1.008\,\text{g/mol}\).
2. Next, calculate the number of moles of NH_3 in 25 grams using the formula: \(\text{moles} = \frac{\text{mass}}{\text{molar mass}} = \frac{25\,\text{g}}{\text{molar mass of NH}_3}\).
3. Then, use Avogadro's number to find the number of molecules. Avogadro's number is \$6.022 \times 10^{23}\( molecules per mole. Multiply the number of moles by Avogadro's number: \)\text{number of molecules} = \text{moles} \times 6.022 \times 10^{23}$.
4. Make sure to keep track of units throughout the calculation to ensure consistency and correctness.
5. Finally, compare your calculated number of molecules with the given options to identify the correct answer.