# chemistry

posted by .

20cm(cube) of a gaseous hydrocarbon were mixed with 90cm(cube) oxygen, and the mixture exploded. At room temperature, 60cm(cube) of gas were left. 40cm(cube) of the gas(cabon(4)oxide) were absorbed by sodium hydroxide, leaving 20cm(cube) of oxygen. find the empirical formular of the hydrocarbon.

• chemistry -

Write some of the hydrocarbon rxns with oxygen. All give CO2 + H2O. The problem would be easier if you were given cc H2O (as a gas) but if you don't have that I would do this.
CH4 + 2O2 ==> C2 + 2H2O

C2H6 + 7O2 ==> 4CO2 + 6H2O

C3H8 + 5O2 --> 3CO2 + 4H2O

2C4H10 + 13O2 ==> 8CO2 + 10H2O

etc. Now what did you have?
CxHy + O2 ==> xCO2 + (y/2)H2O
20 cc CxHy
O2 used must be 90-20 = 70 cc.
CO2 produced = 40 cc

The ratio of these numbers is
CxHy + O2 ....> xCO2 + (y/2)H2O
..20...70.......40........? OR
1.....3.5.......2.......?

That means x must 2 but what is H2O. If you have it in the problem that makes it easier. If you don't have it then you show that of all of the combustions I wrote at the beginning the one with C2H6 is the only one that fits. That is the ONLY one with CO2 twice the hydrocarbon and reactions I didn't write for saturated hydrocarbons become more divergent. Note that H2O in C2H6 (when combusted) is 3x that of the hydrocarbon. So y/2 = 3 and y = 6 and CxHy is C2H6.

## Similar Questions

1. ### Science

Michael dropped a 1 inch cube of wood and a 1 inch cube of laed into an aquarium filled with water.The cube of wood floated and the cube of lead sunk quicklu to the bottom. The cube wood floated because it A.is less dense than the …
2. ### Math

damn i cant post a drawing..there r 2 cubes, cube x and cube y and the length of the cube x is 12cm. A) find the volume of cube x. B) if cube y has a volume equal to 1/8 of the volume of cube x, find the length of its edge.
3. ### Science

Sarah heated two cubes of aluminum to 50 degrees celsius. Cube B has a volume of two cubic centimeters. If the cubes do not touch each other, which of these statements is true?
4. ### physis

a cube of wood floating in water support 1 kg mass resting on the center of its top surface. when the mass is removed the cube rise 2.5cm find the length of cube?
5. ### maths

simplify the following expression without using calculator. -2(-4a squared + b cube) square ........ -2 (-4a squared + b cube)(-4a squared + b cube) -2 (16a square - 4a square b cube + b cube) -2 (+ 16 a square = b cube ) -32a square …
6. ### law of exponents

simplify the following expression without using calculator. -2(-4a squared + b cube) square ........ -2 (-4a squared + b cube)(-4a squared + b cube) -2 (16a square - 4a square b cube + b cube) -2 (+ 16 a square = b cube ) -32a square …
7. ### Science-physics

A bottle weighs 35g when empty,95g when filled with water and 119g when filled with an organic liquid. What is the capacity of the bottle: A-60cm cube B-84cm cube C-130cm cube D-154cm cube
8. ### math

Find the sum of 8x cube y +2xy cube -18and -12x cube y +7xy cube and subtract it from the sum of 19x cube y -17xy cube +12and -21+5xy cube .?
9. ### algebra

You roll a red number cube and a blue number cube. Let A be the event "at least one number cube shows a 6" a) Find P(A) by finding the sum of P(6 on red cube, no 6 on blue cube), P(no 6 on red cube, 6 on blue cube), and P(6 on both …
10. ### physics

the linear expansively of the material of a cube is 12*10-6k. if the length of each side of the cube is 10cm,find the area of one face of the cube and the volume of the cube when its temperature is raised by 30k

More Similar Questions