Question

An unknown oxide of mercury decomposes when heated to form mercury metal and oxygen gas. When a 1.048 g sample of this unknown is heated, 0.971 g of mercury remains.

a. Calculate the moles of mercury and moles of oxygen in the compound.

b. What is the empirical formula of this oxide?





2. A side reaction in today

Answer 1

Moles of mercury = 0.00484 mol.

Moles of oxygen = 0.00481 mol.

The empirical formula is =
`HgO`

Step-by-step explanation:

`Moles =Given\ mass * {Molar\ mass}`

Mass of mercury = 0.971 g

Molar mass of mercury = 200.59 g/mol

Moles of mercury =
`(0.971\ g)/(200.59\ g/mol)` = 0.00484 mol.

Since, the oxide contains only mercury and oxygen. SO,

Mass of O in the sample = Total mass - Mass of Hg

Mass of the sample = 1.048 g

Mass of O in sample = 1.048 g - 0.971 g = 0.077 g

Molar mass of oxygen = 15.999 g/mol

Moles of oxygen =
`(0.077\ g)/(15.999\ g/mol)` = 0.00481 mol.

Taking the simplest ratio for Hg and O as:

0.00484 : 0.00481

= 1 : 1

The empirical formula is =
`HgO`