Question #351ba

1 Answer
Sep 4, 2017

Answer:

#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"" ")|)#