Question

The 30.6-g sample of the compound X2O3 contains 14.4 g of oxygen atoms. What is the molar mass of element X?

Answer 1

Answer:

27 g/mol

Explanation:

To calculate the molar mass of element X, we need to calculate the mass in a given number of moles.

• The moles of X can be calculated by using the ratio of O atoms to X atoms in the molecule:

$14.4 g O*\frac{1molO}{16gO} *\frac{2molX}{3molO}=0.60 mol X$

• The mass of X₂O₃ that is not oxygen, is element X. In other words, the mass of the atoms of the X element contained in the 30.6 g sample is:

30.6 g - 14.4 g = 16.2 g of X

Thus, the molar mass of element X is

16.2 g / 0.60 mol = 27 g/mol

Answer 2

X₂O₃ ===> 3 moles of oxygen == > 48 g O

Molar mass of X₂O₃-------------- 48g O
30,6g --------------------------------- 14,4g

Molar mass = (30,6×48)/14,4
Molar mass = 102g

Molar mass of X₂ = 102 - 48 = 54g
Molar mass of X = 54/2 = 27g

X ==> 27 g/mol ==> Al
X₂O₃ ==> Al₂O₃

:)