Question

A sample of a certain binary compound contains 6.93 g of silicon and 7.89 g of oxygen. What is the percent composition of the compound?

Answer 1

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Answer 2

Given, mass of the silicon = 6.93 g

mass of the oxygen = 7.89 g

Calculate the number of moles of both atoms:

`Number of moles = (given mass)/(molar mass)`

Insert the given values of mass in above formula:

`Number of moles of silicon = (given mass of silicon in g)/(molar mass of silicon)`

=
`(6.93 g)/(28 g/mol)`

=
`0.2475 mol`

`Number of moles of oxygen = (given mass of silicon in g)/(molar mass of silicon)`

=
`(7.89 g)/(16 g/mol)`

=
`0.493125 mol`

Thus,

Total number of moles = number of silicon+ number of mole of oxygen

=
`0.493125 mol+0.2475 mol` =
`0.740625 mol`

`Percentage composition = (number of moles of an atom)/(total number of moles of the compound)* 100`

Put the values in above formula:

`Percentage composition of silicon= (number of moles of silicon)/(total number of moles of the compound)* 100`

`Percentage composition of silicon= (0.2475 mol)/(0.740625 mol)* 100`

=
`33.41 percent`

`Percentage composition of oxygen= (number of moles of oxygen)/(total number of moles of the compound)* 100`

`Percentage composition of silicon= (0.493125 mol)/(0.740625 mol)* 100`

=
`66. 58 percent`

Thus, percent composition of silicon and oxygen is
`33.41 percent`and
`66. 58 percent`