{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

Chapter%2015%20-%20Chemical%20Equilibrium

Chapter%2015%20-%20Chemical%20Equilibrium - Chapter 15...

Info icon This preview shows pages 1–13. Sign up to view the full content.

View Full Document Right Arrow Icon
1 Chapter 15 Chemical Equilibrium
Image of page 1

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
2 Class Business
Image of page 2
3 15.1 The Concept of Equilibrium Chemical equilibrium applies to reactions that can occur in both directions. In a reaction such as: Even though the reactants are constantly forming products and vice-versa the amount of reactants and products does become steady at some point of time. When the net change in the amount of reactants and products is zero, we can say that the reaction has reached equilibrium . The equilibrium is a dynamic equilibrium the amount of products and reactants are constant ( note: they are constant and need not be equal ) , both reactions are still occurring . CH 4 (g) + H 2 O(g) CO(g) + 3H 2 (g)
Image of page 3

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
4 Example Consider the hypothetic reaction A B as shown below (A is red and B is blue ): Does this diagram indicate that the system reaches an equilibrium state? Explain.
Image of page 4
5 The Concept of Equilibrium - Contd... Consider the decomposition of N 2 O 4 : N 2 O 4 ( g ) 2 NO 2 ( g ) Colorless Brown Only N 2 O 4 at low temperature Mixture of N 2 O 4 and NO 2 Although the color stops changing, both reactions are still occurring. Chemical equilibrium occurs when a forward reaction and its reverse reaction proceed at the same rate .
Image of page 5

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
6 The Concept of Equilibrium - Contd... A system approaches equilibrium when both the forward and reverse reactions are occurring. At equilibrium , the forward and reverse reactions are proceeding at the same rate . N 2 O 4 ( g ) 2 NO 2 ( g )
Image of page 6
7 The Concept of Equilibrium - Contd... Once equilibrium is achieved, the amount of each reactant and product remains constant . N 2 O 4 ( g ) 2 NO 2 ( g )
Image of page 7

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
8 15.2 The Equilibrium Constant N 2 O 4 ( g ) 2 NO 2 ( g ) Consider the equilibrium: Forward reaction Reverse reaction N 2 O 4 ( g ) 2 NO 2 ( g ) N 2 O 4 ( g ) 2 NO 2 ( g ) Rate Law Rate = k f [N 2 O 4 ] Rate = k r [NO 2 ] 2 Rate Law Note that each step is an elementary step . So, the order of the reaction is the stoichiometric coefficient.
Image of page 8
9 The Equilibrium Constant - Contd... At equilibrium: k f [N 2 O 4 ] = k r [NO 2 ] 2 Rate f = Rate r k f k r = NO 2 [ ] 2 N 2 O 4 [ ] Equilibrium Constant, K eq What is the unit for K eq ?
Image of page 9

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
10 The Equilibrium Constant - Contd... In general, consider the following reaction: K c = C [ ] c D [ ] d A [ ] a B [ ] b a A + b B c C + d D The equilibrium constant expression in term of concentrations for this reaction is: Law of Mass Action a , b , c , d are the stoichiometric coefficient in the chemical reaction
Image of page 10
11 The Equilibrium Constant - Contd... The equilibrium constant expression depends only on the stoichiometry of the reaction, NOT on its mechanism The equilibrium constant expression and/or the value of K c do NOT say anything about the reaction mechanism or the reaction rate The value of K c is constant at any given temperature and does NOT depend on the initial concentrations of reactants and products: the equilibrium can be reached from both directions By looking at the chemical equation we CAN write the equilibrium constant expression for that reaction. However, the K c = C [ ] c D [ ] d A [ ] a B [ ] b a A + b B c C + d D
Image of page 11

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
12 15.4 The Equilibrium Constant - Contd...
Image of page 12
Image of page 13
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern