Question

determine a massa em gramas de 6,0×10^25 átomos de He

Answer 1

Massa molar do Hélio ( He ) = 4 g/mol

 4 g ------------------------ 6,0.10²³ átomos
x  g ------------------------ $6,0.10 ^{25}$ átomos

6,0 .10²³ x = 4 .$6,0.10 ^{25}$

6,0.10²³ x = $2,4.10^{26}$

$x = \frac{2,4.10 ^{26} }{6,0.10 ^{23} }$

m = 400 g