Quantitative LeChâtelier’s Principle: From ICE Table to MICE table

text over balancing rocks: LeChâtelier’s Principle  - Quantitative

We typically teach students to solve qualitative chemical equilibrium problems using an ICE table, where I, C, and E represent [Initial], [Change], and [Equilibrium] concentrations of each reactant and product in units of mol∙L–1.

At the risk of insulting you, I’ll provide an example, liberated from our class textbook:1




ICE tables are useful for solving Ksp problems and Weak Acid-Base equilibrium problems, too.

Once students master the use of an ICE table, the next major lesson usually involves LeChâtelier’s Principle, LCP:

When any system at equilibrium for a long period of time is subjected to a change in concentrationtemperaturevolume, or pressure, (1) the system changes to a new equilibrium, and (2) this change partly counteracts the applied change.1

We usually teach LCP from a qualitative prespective. A bunch of years ago, I came across the following problem in a most excellent book.2



This problem screams LeChâtelier . . . but it’s a quantitative scream.

Before beginning the quantitative problem solving, look at it qualitatively. If CO2, a reactant, is removed from the system, the reverse reaction will predominate until equilibrium is re-established. This will result in a lower concentration of CO, which will be confirmed with a calculation . . .

To get the correct answer with minimal frustration, I recommend the use of a modified ICE table; my students call it a MICE table. In this instance, the first row—formerly [Initial], is

replaced with [Equilibrium]initial. The next row allows us to account for the [stress], followed by a row for [response], ending with [Equilibrium]final.

Fortunately for us—and thanks to Mother Nature—an equilibrium system at constant temperature has a constant Keq value, regardless of whether its undergone a stress.4

We will solve Sample Problem 2 using a color-coded MICE table corresponding to the problem above. The given information is indicated in blue; the stress is shown in red. The initial response, calculated from the given information is in green, with the subsequent, stoichiometrically-derived responses in brown. [Equilibrium]final as in black.



And so 0.5 mol of CO2(g) would have to be removed from a 1.0-L bulb such that the [CO(g)], after equilibrium has been re-established at the same temperature, reduces to 0.5 mol. This answer makes sense qualitatively: if CO2 is removed from the system

The MICE table can also be used to solve common-ion effect problems related to solubility and to weak acid-base equilibria. We will illustrate with another textbook example:5



This is a LCP problem; the HCl is a stress on the ionization equilibrium of acetic acid:

CH3COOH(aq)  +  H2O(l)    H3O+(aq)  +  CH3COO(aq)

An increase in [H3O+] will temporarily favour the reverse reaction, which will supress the ionization of acetic acid. This is the correct answer, qualitatively speaking.

Textbooks usually solve problems like these with an ICE table.



There is nothing wrong with this problem-solving methodology. It’s easy-looking and its neat and clean.

But it does not pay homage to the stress-response manner in which we explain LCP.

Using a MICE table, we can see separate steps for stress and response: the 0.010 molL–1 HCl is the stress. As for the response, LCP tells us what will occur, just not how much. We denote this with a y. Take a look . . .



To the (initial) chagrin of some students, this appears to be a two-variable problem. It won’t take long for someone to point out that (x – y), itself an unknown, may be replaced with another unknown, such as q.

And so the final row of the MICE table reduces to the final row of Table 3, and hence will furnish the same answer.

The beauty of the MICE table is its pedagogical consistency with our original qualitative explanation of LCP. For solving Common Ion Effect problems, there are no smoke and mirrors. It’s straight forward: equilibrium-stress-response-equilibrium.


LeChatelier's Chart from PowerPoint Slideshow described

Screenshot from Equilibrium PowerPoint SlideShow in Supporting Information

I humbly suggest that you consider giving this a try. I offer a PowerPoint presentation (to be used in SlideShow mode) that I use with my students in the Supporting Information. I hope you find it useful.

May peace be with you,


  1. General Chemistry, 10th ed, Ebbing and Gammon, Brooks/Cole CENGAGE Learning, 2013, p 610 example 14.8
  2. Wikipedia contributors. (2022, February 7). Le Chatelier's principle. In Wikipedia, The Free Encyclopedia. Retrieved 16:50, March 3, 2022, from https://en.wikipedia.org/w/index.php?title=Le_Chatelier%27s_principle&oldid=1070529824

  3. Chemistry: Theory and Problems, Book 2, James A Hebden, McGraw-Hill Ryerson, 1980.

  4. Unless the stress is a change in temperature

  5. General Chemistry, 10th ed, Ebbing and Gammon, Brooks/Cole CENGAGE Learning, 2013, p 683 example 16.9


Supporting Information: 


Students who demonstrate understanding can refine the design of a chemical system by specifying a change in conditions that would produce increased amounts of products at equilibrium.

*More information about all DCI for HS-PS1 can be found at https://www.nextgenscience.org/dci-arrangement/hs-ps1-matter-and-its-interactions and further resources at https://www.nextgenscience.org.


Students who demonstrate understanding can refine the design of a chemical system by specifying a change in conditions that would produce increased amounts of products at equilibrium.

Assessment Boundary:

Assessment is limited to specifying the change in only one variable at a time. Assessment does not include calculating equilibrium constants and concentrations.


Emphasis is on the application of Le Chatelier’s Principle and on refining designs of chemical reaction systems, including descriptions of the connection between changes made at the macroscopic level and what happens at the molecular level. Examples of designs could include different ways to increase product formation including adding reactants or removing products.