so a hydrocarbon has the empirical formula CH2 and a density 1.88g/L at 0C and 1 atm ...
what is a possible formula for the hydrocarbon and it tells me to use the density ideal gas equation.
i don't want the answer so much as i want the method... help please,,
2006-08-03 17:45:53 · 10 answers · asked by Mikey X 2 in Science & Mathematics ➔ Chemistry
i still don't understand how this links to the other possible formulas.
2006-08-03 18:02:58 · update #1
You need the formula, so you need the molar mass first.
This hydrocarbon should be a gas, and for gases:
pV=nRT
where R = 8,314 J/(mol*K)
We know the denisity, it means that 1,88g of this hydrocarbon is in 1 L at 1 atm and 0 *C, so
V = 1L = 0,001 m3
p = 1 atm = 1,013*10^5 Pa
T = 0*C = 273K
You can find the formula the number of moles:
n = (pV)/(RT) = 0,0466 mol, and you know it is 1,88g.
So your molar mass is
m / n= 42 g/mol.
The molar mass of CH2 is 14.
42 / 14 = 3.
So your formula is C3H6. Your hydrocarbon is propene.
2006-08-03 19:40:38 · answer #1 · answered by hi 2 · 5⤊ 0⤋
Ok, this is a fun one. Take what we know. The equation we're using is:
PV = nRT
Given values:
P = 1atm
T = 0C = 273K
d = 1.88 g/L
R is a constant
So, out of the equation, we still have V and n unknown, but we have d as extra info. You need the formula for the compound, and one way to get there is the empirical formula plus a molar mass. Knowing that d = m/V and that you want M, you should be able to manipulate the equation to get what you want. I've given you the organization, so I hope you can do the rest. Check to make sure your units work.
Wow, a high school chem teaching bailing on this one. That's encouraging.
2006-08-04 00:55:22 · answer #2 · answered by Phil 5 · 0⤊ 0⤋
u can use PV=nRT.
P, pressure is given, V is 1L, R is constant (8.314 for std atp), T is 273K or 0C.
find n, the number of mole.
then find from 1.88g/L the mole, then empirical formula
2006-08-04 01:00:17 · answer #3 · answered by Ant 2 · 0⤊ 0⤋
I opened your question because I used to teach high school chemistry, but it has been way too long. I can't help you with the answer or the method.
2006-08-04 00:51:40 · answer #4 · answered by Irish1952 7 · 0⤊ 0⤋
PV=nRT
P=Pressure
V= volume
n= # moles
R= constant
T= Temp (in Kelvin)
R value= 0.082058 L * atm/ (K*mol)
2006-08-04 01:04:35 · answer #5 · answered by Helzabet 6 · 0⤊ 0⤋
I hate stoichiometry!
2006-08-04 03:58:34 · answer #6 · answered by kawaii_berry 2 · 0⤊ 0⤋
read your books
2006-08-04 00:50:19 · answer #7 · answered by thinking man 3 · 0⤊ 0⤋
sorry, i don't have a clue
2006-08-04 00:49:28 · answer #8 · answered by Deana G 5 · 0⤊ 0⤋
i have NO idea.. srrry about that =(
2006-08-04 00:49:06 · answer #9 · answered by ▪♥▪ 3 · 0⤊ 0⤋
boo hoo we all need help on home work go tell a teacher that you need help duh!!!!
2006-08-04 00:50:19 · answer #10 · answered by Nervous Wreck 1 · 0⤊ 0⤋