Question

Find out the number of atoms in 2.31 × 10^-6  copper. (Atomic mass of Cu 63.5 a.m.u.).

Answer 1

63.5 g Cu = 6.022 × 10²³ Cu-atoms.

2.31 × 10^-6 Cu = \(\frac{6.022\times 10^{23}\times2.31\times 10^{-6}}{63.5}\)

= 0.219 × 10¹⁷ 

= 2.19 × 10¹⁶ Cu-atoms