Question

Determine a massa, em gramas, de:
a) 6,0 . 10^25 átomos de He
(He = 4)
b) 3,0 . 10^22 átomos de Ne
(Ne = 20)

Answer 1

a) Massa molecular do He = 4 g/mol

1 mol = 6*10²³ átomos

6*10²³ átomos He -------------- 4g
6*10²⁵ átomos He -------------- x

x = 4*10² g
x = 400g He

b) Massa molecular do Ne = 20 g/mol

1 mol = 6*10²³ átomos

6*10²³ átomos Ne -------------- 20g
3*10²² átomos Ne -------------- y

y = 10*10⁻¹ g
y = 1g Ne