Question

Question #351ba

Answer 1

`0.100` `"mol O"`

Explanation:

We're asked to find the number of moles of oxygen in an unknown compound containing `"C"`, `"H"`, and `"O"`, given that `3.00` `"g"` of this compound underwent complete combustion.

We're given that the compound contained `0.100` `"mol C"` and `0.200` `"mol H"`. Let's convert these values to grams using the molar mass of the elements:

`0.100cancel("mol C")((12.01color(white)(l)"g C")/(1cancel("mol C"))) = 1.201color(white)(l)"g C"`

`0.200cancel("mol H")((1.01color(white)(l)"g H")/(1cancel("mol H"))) = 0.202color(white)(l)"g H"`

The mass of the compound was given as `3.00` `"g"`. Since oxygen is the only other element in the compound, the mass of oxygen is

`3.00color(white)(l)"g" - 1.201color(white)(l)"g C" - 0.202color(white)(l)"g H" = color(red)(ul(1.597color(white)(l)"g O"`

We can find the moles of `"O"` using its molar mass:

`color(red)(1.597color(white)(l)"g O")((1color(white)(l)"mol O")/(16.00cancel("g O"))) = color(blue)(ulbar(|stackrel(" ")(" "0.100color(white)(l)"mol O"" ")|)`