How many grams of NH_3 are needed to provide the same number of molecules as in 0.15 g of SF_6?

• A. 0.21 g
• B. 0.082 g
• C. 0.15 g
• D. 0.032 g

Answer: (D)

Verified step by step guidance

1. Calculate the number of moles of SF_6 in 0.15 g by using its molar mass. The molar mass of SF_6 is calculated by summing the atomic masses: sulfur (S) is approximately 32.07 g/mol and fluorine (F) is approximately 18.998 g/mol. So, molar mass of SF_6 = 32.07 + 6 \times 18.998.
2. Use the formula for moles: \(\text{moles} = \frac{\text{mass}}{\text{molar mass}}\). Substitute the mass of SF_6 (0.15 g) and its molar mass to find the moles of SF_6.
3. Since the problem asks for the amount of NH_3 that has the same number of molecules, recall that the number of molecules is proportional to the number of moles. Therefore, the moles of NH_3 needed are equal to the moles of SF_6 calculated.
4. Calculate the molar mass of NH_3 by adding the atomic masses: nitrogen (N) is approximately 14.01 g/mol and hydrogen (H) is approximately 1.008 g/mol. So, molar mass of NH_3 = 14.01 + 3 \times 1.008.
5. Finally, calculate the mass of NH_3 needed using the formula \(\text{mass} = \text{moles} \times \text{molar mass}\). Use the moles found in step 3 and the molar mass from step 4 to find the mass of NH_3 that contains the same number of molecules as 0.15 g of SF_6.