Question

Calculate the number of mole in 48g helium and 46g sodium atom

Answer 1

a)46g of Na atom

atomic mass of Na=23u

Number of particles=Number of Moles x N

⇒(given weight/ Gram atomic weight) x 6.023 x 10²³

=(46/23)x 6.023 x 10²³

=2x 6.023 x 10²³

⇒12.046 x 10 ²³Na particles

∴46 g of Na contains 12.044 x 10 ²³

 b)8g of O2 moles

molecular mass of O2=32u

No. Of  molecules in O2 molecules=(8/32) x 6.022 x 10²³⇒0.25 x 6.023 x 10 ²³

⇒1.5055x 10 ²³ molecules

∴8g of O2 contains 1.5055x 10²³ molecules

c)0.1 moles of Carbon atom

1mole of carbon atom = 12 g of carbon  contains 6.022 x 10²³ carbon atoms

0.1 moles of carbon contain =0.1 x 6.023 x 10²³

⇒ 6.023x10²² carbon atoms

∴0. mole contains  6.023x10²² carbon atoms..