Determine the number of molecules contained in 3.5 mol of ammonia.

n (NH3) = 3.5 mol.
Determine the number of molecules contained in a given amount of ammonia. We write down the solution.
N = n * Na.
Where N is the number of molecules.
n is the amount of substance.
Na – Avogardo’s number, constant equal to 6.02 * 10’23.
Find the number of molecules.
N = 3.5 * 6.02 * 10’23 = 21.07 * 10’23 molecules.
This means that 3.5 mol of ammonia contains 21.07 * 10’23 molecules.
Answer: N = 21.07 * 10’23 molecules.

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