LAQ : 51 grams of ammonia is equivalent to how many gram moles of ammonia? How many molecules of ammonia are there?

Question

51 grams of ammonia is equivalent to how many gram moles of ammonia? How many molecules of ammonia are there? [Ans. 3 mol, 1.806 × 10²⁴]

Answer

Given the mass of ammonia = 51 g

Molar mass of ammonia (NH₃) = 14 + 1 × 3 = 17 g

Step 1: Calculation of mole

number of moles = mass \over molar\ mass

= 51 \over 17

= 3 moles of ammonia

Step 2: Calculation of molecules

number of molecules = number of moles × Avogadro’s number

= 3 × 6.022 × 10²³

= 1.8066 × 10²⁴