Register to reply

Need major help

by 1uigi
Tags: major
Share this thread:
Apr15-06, 05:39 PM
P: 1
I'm learning equilibirum in class, but I am stuck on this question. DOes anyone how how to do this problem? I use the quadratic formula but end end with answers A and B, but the correct answer is A. Can someone show me step by step how to do this problem? thanks

9. At a certain temperature, T, K for the reaction below is 7.5 liters/mole.
2NO2 <===> N2O4
If 2.0 moles of NO2 are placed in a 2.0-liter container and permitted to react at this temperature, what will be the concentration of N2O4 at equilibrium?

a) 0.39 moles/liter
b) 0.65 moles/liter
c) 0.82 moles/liter
d) 7.5 moles/liter
e) none of these
Phys.Org News Partner Science news on
Experts defend operational earthquake forecasting, counter critiques
EU urged to convert TV frequencies to mobile broadband
Sierra Nevada freshwater runoff could drop 26 percent by 2100
Apr15-06, 11:49 PM
P: 102
You did the problem correctly. You end up having to solve the quadratic equation 30.x2 - 31x + 7.5 = 0. You get the answers of x = .39 and x = .65.

Now, think about the problem. You are starting with 1.0 M NO2, correct? You should notice that the equilibrium concentration of NO2 will be 1.0 - 2x, and the equilibrium concentration of N2O4 will be x.

If x was .65, then 1.0 - 2x would yield a negative concentration, which is physically impossible. Therefore, the only correct answer can be [N2O4] = .39 M because 1.0 - 2(.39) gives you a positive concentration.

Register to reply

Related Discussions
Math major and engineering major Academic Guidance 5
Need Major Help please! Engineering, Comp Sci, & Technology Homework 1
Double Major or Single Major? Academic Guidance 4
What's your major? General Discussion 30
Which Major...? General Discussion 9