Question #fc002

1 Answer
Dec 14, 2017

P=4.70atm

Explanation:

Alright, so we are going to use the ideal gas law to solve this one. That law simply states that

PV=nRT

In this equation, P is pressure in atm
V is volume in liters
n is the amount of gas in moles
R is a constant equal to (0.08206L*atm)/(K*mol)
And finally, T is temperature in kelvin

So we are trying to solve for P, so we need that on one side of the equation. We can do that by just dividing by V

(PcancelV)/cancelV=(nRT)/V

P=(nRT)/V

Ok, at this point lets start plugging variables in.

V=10.0L

P=(nRT)/(10.0L)

To convert C^o to K we just add 273

K=C^o +273

K=200^oC+273

T=473K

P=(n*R*473K)/(10.0L)

Now for the tricky part. We need to convert 32g of C_2H_6 into moles. To do this we must first find the molar mass of C_2H_6, then convert 32g to moles.

The molar mass is going to equal (30.07g)/(mol) because we simply add the atomic mass of both elements:

C=12.0107*2
H=1.00794 *6
....................................
(30.07g)/(mol)

So now we need to find out how much moles 32g is

n=(mol)/(30.07g)*32g

n=(mol)/(30.07cancelg)*32cancelg

n=(32mol)/(30.07)

n=1.1mol

Ok, lets plug that in and the constant (R). I'd like to note that I like to put the constant outside the equations as it makes it a lot easier.

P=(n*R*473K)/(10.0L)

P=(1.1mol*473K)/(10.0L)(0.08206L*atm)/(K*mol)

This is the fun part, were you cancel out all the conversion names. NOTE: since you are looking to P, we should have atm left over at the end

P=(1.1cancel(mol)*473cancelK)/(10.0cancelL)(0.08206cancelL*atm)/(cancelK*cancel(mol))

Now, finally, we just solve! Notice that atm is all that left....

P=(1.1*473*0.08206*atm)/(10.0)

P=4.70atm

Hope this helped! If you have any more questions feel free to ask them!

~Chandler Dowd