Question

how many atoms are present in 1 ml of NH3 at STP ?

Answer 1

So 1 ml has 1/22400 moles at STP.1 mole = 6.022 x 1023 molecules. So number of molecules of ammonia in 1 ml = 6.022 x 1023/22400. Now, multiply this number by 4 to get the total number of atoms as each molecule of ammonia has 4 atoms ( 1 N and 3 H).

Answer 2

Answer: $108.4\times 10^{18}$ atoms

Explanation: According to avogadro's law, 1 mole of every substance occupies 22.4 Liters at STP and contains avogadro's number $6.023\times 10^{23}$ of particles.

To calculate the moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given volume}}{\text {Molar volume}}$

$\text{Number of moles}=\frac{1 ml}{22400ml}=4.5\times 10^{-5}moles$   (1L=1000ml)

Now 1 mole of $NH_3$ molecule contains = $6.023\times 10^{23}$ of molecules

1 mole of $NH_3$ molecule contains =$4\times 6.023\times 10^{23}=24.1\times 10^{23}$ atoms

$4.5\times 10^{-5}moles$ of $NH_3$ molecule contains = $\frac{24.1\times 10^{23}}{1}\times 4.5\times 10^{-5}=108.4\times 10^{18}$ atoms