Question #a39a6
1 Answer
Here's what I got.
Explanation:
The idea here is that concentrated sulfuric acid will act as a dehydrating agent and remove water molecules from the two acids.
Concentrated sulfuric acid will dehydrate formic acid,
#"HCOOH"_text((l]) stackrel(color(red)("H"_2"SO"_text(4(l]))color(white)(aaa))(->) "H"_2"O"_text((l]) + "CO"_text((g])# #uarr#
Notice that you have a
Sulfuric acid will dehydrate oxalic acid,
#"H"_2"C"_2"O"_text(4(l]) stackrel(color(red)("H"_2"SO"_text(4(l]))color(white)(aaa))(->) "H"_2"O"_text((l]) + "CO"_text((g])# #uarr + "CO"_text(2(g]) uarr#
Once again, you have
Your goal here is to find the ratio that exists between the number of moles of formic acid and the number of moles of oxalic acid, ie.e
The total number of moles of gas produced by the dehydration reaction will be equal to
#n_"total" = x + y + y = overbrace((x+y))^(color(purple)("moles of CO")) + overbrace(y)^(color(blue)("moles of CO"_2)) = x + 2y#
Now, the trick is to recognize the fact that potassium hydroxide,
Since the gaseous mixture is kept under the same conditions for pressure and temperature, a decrease in volume is equivalent to a decrease in number of moles.
In other words, the volume of the mixture decreases because the moles of carbon dioxide are absorbed by the potassium hydroxide solution.
The mole fraction of carbon dioxide in the mixture will be equal to
#color(purple)(|bar(ul(color(white)(a/a)color(black)(chi_(CO_2) = "number of moles of CO"_2/"total number of moles of gas")color(white)(a/a)|)))#
In your case, you have
#chi_(CO_2) = (y color(red)(cancel(color(black)("moles"))))/((x + 2y)color(red)(cancel(color(black)("moles")))) = y/(x + 2y)#
If all the moles of carbon dioxide were absorbed by the solution, you can say that the mole fraction of carbon dioxide in the mixture is equivalent to
#y/(x + 2y) = 1/6#
This will be equivalent to
#6y = x + 2y#
#4y = x implies x/y = color(green)(|bar(ul(color(white)(a/a)4/1color(white)(a/a)|)))#
The mixture contained four time more moles of formic acid than of oxalic acid.