To determine the number of atoms present in
2.24dm3 of
NH3(g) at standard temperature and pressure (STP), we should first recall the concept of molar volume. At STP, one mole of any ideal gas occupies
22.4dm3. We can use this information to calculate the number of moles of ammonia gas in the given volume.
The number of moles
(n) is given by:
n=‌| ‌ Volume ‌ |
| ‌ Molar Volume ‌ |
For
NH3 at STP:
n=‌=0.1‌mol Each molecule of ammonia
(NH3) contains 1 nitrogen atom and 3 hydrogen atoms, totalling 4 atoms. To find the total number of atoms in 0.1 mole of ammonia, we multiply the number of atoms in one molecule by Avogadro's number (approximately
6.022×1023 atoms
∕mol ), which tells us the number of particles (atoms, molecules, ions, etc.) in one mole of a substance.
The total number of atoms in 0.1 mole of
NH3 is:
Total Number of Atoms
= moles
× Avogadro's number
× atoms per molecule
=0.1 moles
×6.022×1023 atoms
∕mol×4 atoms
∕ molecule
Now we calculate the total number of atoms:
Total Number of Atoms
=0.1×6.022×1023×4=0.1×4×6.022×1023 =2.4088×1022 atoms
Therefore, the correct answer is Option B:
2.4088×1023 atoms.