A mixture of 10cm^3 of methane and 10cm^3 of ethane was sparked with an excess of oxygen. After cooling to room temperature, the reidual gas was passed through pottasium hydroxide.
what volume of gas was absorbed by the alkali?
A)15cm^3
B)20cm^3
C)30cm^3
D)40cm^3
2007-06-13 08:03:47 · 3 answers · asked by Anonymous in Science & Mathematics ➔ Chemistry
Methane and ethane are hydrocarbons that are burned completely in oxygen to CO2 + H2O.
CH4 + 2O2 ===> CO2 + 2H2O
2C2H6 +7O2 ===> 4CO2 + 6H2O
The CO2 is absorbed by KOH because 2KOH + CO2 ===> K2CO3 + H2O.
The problem involves Avogadro's principle, that equal volumes of gases contain equal numbers of molecules. So ignoring the O2 and H2O,
CH4 ===> CO2, and
C2H6 ===> 2CO2
That means that the 10 cu cm CH4 ===> 10 cu cm CO2. Too, 10 cu cm C2H6 ===> 20 cu cm CO2. And 10 + 20 = 30 cu cm, so C).
"Fortitude," who answered above, is completely correct. The person who composed the question didn't consider that KOH also absorbs H2O as well as CO2.
2007-06-13 08:39:46 · answer #1 · answered by steve_geo1 7 · 0⤊ 0⤋
Wow this is a hard quistion but im thinking it is B 20 cm^3
2007-06-13 08:08:32 · answer #2 · answered by xXLilxShawtieXx 3 1 · 0⤊ 0⤋
30 should be left over as carbon dioxide,
and 50 should have been absorbed as water.
You don't have a correct answer listed.
2007-06-13 08:11:52 · answer #3 · answered by Anonymous · 0⤊ 0⤋