Calculate the composition of dry air at 3800 K and 1 bar. Take the initial composition as 0.78 mol N2, 0.21 mol O2, and 0.01 mol Ar. Neglect the ionization of NO.
Using the NIST-JANAF tables, thermodynamic values are found.
I'm confused about how to find K1 and K2 of the two reactions below. The temperature given is 3800 K and the standard pressure is 1 bar.
K1 = 0.0895 and K2 = 2.221
I don't know if the values of K1 and K2 are right.
(1) N2 + O2 = 2NO
(2) 02 = 2O
Steps
1. Create an icebox chart
2. Find K1 and K2 using the thermodynamic values from the NIST-JANAF tables
3. To solve for (a) and (b) in the icebox chart ---- divide the 1st equation (K1) by the 2nd equation (K2) and solve for (a) as a function of (b)
4. Find the moles of N2, O, O2, NO from the icebox chart once (a) and (b) values are found. And the moles of Ar are given.
To find the values of K1 and K2, you need to use the thermodynamic values from the NIST-JANAF tables. These tables provide thermodynamic equilibrium constants (K) at various temperatures and pressures.
1. Start by finding the NIST-JANAF tables for the reactions you're interested in, which are:
(1) N2 + O2 = 2NO
(2) O2 = 2O
2. Look up the values for K1 and K2 at the given temperature of 3800 K and the standard pressure of 1 bar. These values can usually be found in the NIST-JANAF tables under the "equilibrium constants" or "thermodynamic properties" section.
3. Once you have the values of K1 and K2, you can proceed with solving for (a) and (b) in the icebox chart.
- Start by writing the balanced equations and setting up an icebox chart:
(1) N2 + O2 = 2NO
(2) O2 = 2O
N2 O2 O NO Ar
Initial moles 0.78 0.21 0 0 0.01
Change -a -b +b +2a 0
Equilibrium 0.78-a 0.21-b b 2a 0.01
4. For the reaction (1), divide the equation (1) (K1) by equation (2) (K2):
(N2 + O2) / O2 = (2NO) / 2O
(0.78 - a) / (0.21 - b) = (2a) / (b)
Cross-multiply:
(0.78 - a) * b = (0.21 - b) * (2a)
Now you have an equation with (a) and (b), which you can solve simultaneously to find their values.
5. Once you have the values of (a) and (b), you can substitute them back into the icebox chart and calculate the moles of N2, O, O2, NO, and Ar at equilibrium.
Keep in mind that the values of K1 and K2 you obtain from the NIST-JANAF tables are specific to the given temperature and pressure. Make sure you are using the correct values for your calculations.