What is the mass of 0.5 moles of #"CO"_2# ?
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We use the following formula
#n("moles") = (m("mass"))/(M("molar mass"))#
Rearranging this equation, we find that
#m = n * M#
We are given the moles #(0.5)#, so we need to find the molar mass. I'm assuming you are given a table of molar values of elements such as carbon is #"12 g/mol"#..
So to find moles, we add all the molar values together
#M("CO"_2) = M("C") + 2*M("O")#
#M("CO"_2) = (12 + 2*16) \ "g/mol"#
#M("CO"_2) = 44 \ "g/mol"#
Therefore, we can then use the above-rearranged equation to find #m#:
#m = "0.5 moles" * "44 g/mol"#
#m = "22 g"#
To find the mass of a certain number of moles of a substance, we multiply the number of moles of the substance by its molar mass.
Carbon dioxide #(CO_2)# has a molar mass of #44.01 \ "g/mol"#. Here, there are #0.5 \ "mol"# of the molecule. So, the mass of this sample is:
#m=(44.01 \ "g")/(color(red)cancelcolor(black)"mol")*0.5color(red)cancelcolor(black)"mol"#
#~~22 \ "g"#
