Number of N atoms in 0.650mol NH3.
The Correct Answer and Explanation is:
Correct Answer:
To find the number of nitrogen atoms in 0.650 mol of ammonia (NH₃), we follow this step:
Each NH₃ molecule contains 1 nitrogen atom.
So, in 0.650 mol of NH₃, there are: 0.650 mol NH₃×6.022×1023 molecules1 mol×1 N atom1 NH₃ molecule=3.91×1023 N atoms0.650 \text{ mol NH₃} \times \frac{6.022 \times 10^{23} \text{ molecules}}{1 \text{ mol}} \times \frac{1 \text{ N atom}}{1 \text{ NH₃ molecule}} = 3.91 \times 10^{23} \text{ N atoms}
Final Answer:
3.91 × 10²³ nitrogen atoms
In chemistry, the mole (mol) is a fundamental unit used to express amounts of a chemical substance. One mole of any substance contains Avogadro’s number of entities (atoms, molecules, ions, etc.), which is 6.022 × 10²³. This very large number helps us translate between the microscopic scale of atoms and molecules and the macroscopic scale we observe in the laboratory.
Ammonia (NH₃) is a molecule composed of 1 nitrogen (N) atom and 3 hydrogen (H) atoms. So for each individual molecule of NH₃, there is exactly one nitrogen atom.
When we are told we have 0.650 moles of NH₃, we can use Avogadro’s number to calculate the total number of molecules in that sample: 0.650 mol×6.022×1023 molecules/mol=3.9143×1023 molecules0.650 \text{ mol} \times 6.022 \times 10^{23} \text{ molecules/mol} = 3.9143 \times 10^{23} \text{ molecules}
Since each molecule contains one nitrogen atom, the number of nitrogen atoms is the same as the number of molecules: 3.9143×1023 nitrogen atoms3.9143 \times 10^{23} \text{ nitrogen atoms}
Rounding to three significant figures, which matches the precision of the given quantity (0.650 mol), we get: 3.91×1023 nitrogen atoms\boxed{3.91 \times 10^{23} \text{ nitrogen atoms}}
This problem emphasizes a key point in stoichiometry: the mole-to-particle relationship is essential for converting between macroscopic quantities (like grams or moles) and the microscopic world (like atoms or molecules).
