Chapter 3: Atoms and Molecules

Sodium atom and ion differ by one electron. For 100 moles each of sodium atoms and ions there would be a difference of 100 moles of electrons.

Mass of 100 moles of electrons= 5.48002 g

Mass of 1 mole of electron = 5.48002 / 100 g

Mass of one electron =  5.48002 /100 × 6.022 ×10²³

= 9.1 ×10²⁸ g

=  9.1×10^-31 kg

The molar mass of HgS = The molar mass of Hg + the molar mass of S

= 200.6 + 32 = 232.6 g mol^–1

1molecule of HgS contains 1 atom of Hg

232.6 g of HgS contains 200.6 g of Hg

Therefore, Mass of Hg in 225 g of HgS = 200.6 X 225 /232.6 = 194.04g

One mole of screws weigh = 2.475 ×10²⁴g

= 2.475×10²¹ kg

Mass of the Earth / Mass of 1 mole of screws = 5.98 ×10²⁴ kg 2.475×10²¹

= 2.4 ×10

Mass of earth is 2.4×10³ times the mass of screws

The earth is 2400 times heavier than one mole of screws

Solution coming soon.