# Homework Help: Parameterization Question

1. Sep 29, 2010

### jegues

1. The problem statement, all variables and given/known data

Ethylene oxide is produced industrially from the reaction of ethylene with oxygen at atmospheric pressure and 283 oC, in the presence of silver catalyst.

$$C_{2}H_{4} + O_{2} \rightarrow C_{2}H_{4}O$$

Assuming 100 % yield, how many kg of ethylene oxide can be produced from 35100 L of a mixture containing ethylene and oxygen in 1:1 molar ratio?

2. Relevant equations

3. The attempt at a solution

First I balanced the equation like so,

$$2C_{2}H_{4} + O_{2} \rightarrow 2C_{2}H_{4}O$$

I then converted the temp. from celsius to kelvin so,

525.15K

I'm not sure what value I should use for pressure, in a question like this am I just assuming that P = 1atm?

I then applied PV= nRT and solved for moles. Once I have the number of moles I used the molar mass to get it into grams and then I converted grams to kilograms.

I still got the answer wrong however.

What am I doing wrong?

EDIT:Also, what value for the gas constant do I use that will work with the units K, mol, atm, and L?

Last edited: Sep 29, 2010
2. Sep 30, 2010

### Staff: Mentor

You are told it is happening at atmospheric pressure, and that means 1 atm.

R value - check whichever fits the units. There are many lists of R values on the web.

3. Sep 30, 2010

### jegues

$$n = \frac{PV}{RT}$$

$$n = \frac{1atm \cdot 35100L}{0.082 \cdot 525.15K} = 815.10 \text{mols of Ethylene oxide}$$

Molar mass of Ethylene oxide 44.05 g/mol

So,

$$44.05\text{g/mol} \cdot 815.10\text{mols} = 35905.07g = 35.91kg$$

What am I doing wrong?

Last edited: Sep 30, 2010
4. Sep 30, 2010

### Staff: Mentor

Think about initial amounts of gases and stoichiometry.

--

5. Sep 30, 2010

### jegues

Oh, the temperature should be 556.15K, my bad!

Can I get another nudge? It's still not obvious to me what to do next.

6. Oct 1, 2010

### Staff: Mentor

Do you have enough oxygen?

7. Oct 1, 2010

### jegues

So I should use PV=nRT to find the mols of oxygen, then I'll know whether it's a limiting reactant or not, correct?

8. Oct 1, 2010

### Staff: Mentor

Yes and no. Yes - you have to check what is a limiting reagent. No - you don't need PV=nRT for that. You are already told what is mixture composition.

--

9. Oct 2, 2010

### jegues

It says a 1:1 molar ratio, right?