Question

For a 4.35g sample of ammonia gas (NH3), determine the total number of atom in a sample.

Answer 1

Answer:

Mass of Ammonia gas, m = 4.35 g [given]

Molar mass of ammonia, M = 17 g/mol  

∴ No. of moles, n = Mass / Molar mass = 4.35 / 17 = 0.25 moles

We know that,

I mole of gas contains 6.022 * 10²³ molecules  

∴ 0.25 moles of Ammonia will contain = 0.25 * 6.022 * 10²³ molecules = 1.5055 * 10²³ molecules

Also, 1 molecule of Ammonia gas contains 4 atoms

∴ No. of atoms in 1.5055*10²³ molecules of ammonia will contain  

= 4 * 1.5055*10²³ atoms

= 6.022 * 10²³ atoms

Hence, the total number of atoms in a sample of 4.35 g of ammonia gas is 6.022 * 10²³.