Question

What is the mass of a sample of NH3 containing 7.20 x 1024 molecules of NH3? (5 points) Group of answer choices 203 grams 161 grams 214 grams 187 grams

Answer 1

Answer:

203 grams

Explanation:

The no. of moles of (6.3 x 10²⁴ molecules--Avagadros number) of NH₃ = (1.0 mol)(7.2 x 10²⁴ molecules)/(6.022 x 10²³ molecules) = 11.96 mol.

The no. of grams of NH₃ present = no. of moles x molar mass = (11.96 mol)(17.0 g/mol) = 203.3 g ≅ 203.0 g.