Final answer:
To calculate the number of molecules in 5.00 grams of NH3, we determine the molar mass and then use it to find moles, which are then multiplied by Avogadro's number to get molecules. The correct answer is D. 1.77 × 1023 molecules.
Step-by-step explanation:
The question asks how many molecules are contained in 5.00 grams of NH3 (ammonia). To find this, we need to know the molar mass of ammonia and use Avogadro's number, which is 6.02 × 1023 molecules/mol.
Firstly, let's calculate the molar mass of NH3:
- Nitrogen (N) has a molar mass of ~14.01 g/mol
- Hydrogen (H) has a molar mass of ~1.008 g/mol
Therefore, the molar mass of NH3 is 14.01 g/mol (for N) + 3 × 1.008 g/mol (for each of the three H's) = 17.034 g/mol.
To find the number of moles of NH3 in 5.00 grams we use the formula:
moles = mass / molar mass
In this case:
moles NH3 = 5.00 g / 17.034 g/mol = 0.2935 mol
Now, to find the number of molecules of NH3, we multiply the number of moles by Avogadro's number:
molecules = moles × Avogadro's number
molecules NH3 = 0.2935 mol × 6.02 × 1023 molecules/mol
This yields approximately 1.77 × 1023 molecules.
The correct answer to how many molecules are contained in 5.00 grams of NH3 is D. 1.77 × 1023.