Question

A sample of gold (Au) has a mass of 45.65 g.

A) Calculate the number of moles of gold (Au) in the sample. Show your work and highlight your final answer.

B) Calculate the number of atoms of gold (Au) in the sample. (Use your answer from Part A.) Show your work and highlight your final answer.

Answer 1

A. The molar mass of gold is 196.97 g/mol. To find the number of moles, we divide the mass by the molar mass:
(45.65 g Au) / (196.97 g/mol) = 0.2318 mol Au (rounded to 4 significant figures)

B. One mole contains 6.02 x 10^23 atoms, so we multiply this to the number of moles from part A to find the total number of atoms:
(0.2318 mol Au) * (6.02 x 10^23 atoms/mol) = 1.395 x 10^23 Au atoms