Question

A compound has the formula X2O3 where x is an unknown element. If the compound is 24.26% oxygen, what element does x represent?

Answer 1

Answer:

Element X is Arsenic (Ar)

Explanation:

We are given the compound X₂O₃

The compound is 24.26% Oxygen

We are required to identify element X

Step 1: Determine the mass of Oxygen in the compound

Atomic mass of Oxygen is 16.0 g

There are three oxygen atoms in the compound

Therefore;

Mass of oxygen in the compound = 3 × 16

                                                        = 48 g

Step 2: Total mass of the compound

Total percentage = 100%

But, Oxygen in the compound  is 24.26 % and has a mass of 48 g

Therefore;

Mass of the compound = (48 g ÷ 24.26 ) × 100

                                      = 197.857 g

Step 3 mass of X in the compound

Since we know the mass of oxygen in the compound and the mass of the compound we can determine the mass of X

Mass of X in the compound = Mass of the compound - Mass of Oxygen in the compound

                                               = 197.857 g - 48 g

                                               = 149.857 g

But there are two atoms of X in the compound.

Therefore, molar mass of X = 149.857 g ÷ 2

                                             = 74.929 g

Step 4: Identity of element X

We then we need to identify the element with a molar mass of 74.929 g

Therefore, the element represented above is Arsenic which has an atomic mass of 74.92.

Thus, our compound is Ar₂O₃