How do I complete an ICE table for a solution of nitrous acid, HNO2, one of the acids associated with acid deposition?
Part of it depends upon what you know about the HNO2 and part on what you want to know. For example, for 0.1M HNO2, you want to know H^+, then
.......HNO2 ==> H^+ + NO2^-
I.......0.1......0......0
C.......-x.......x......x
E.......0.1-x....x......x
Then you substitute the E-line into the Ka expression and solve for x.
To complete an ICE (Initial, Change, Equilibrium) table for a solution of nitrous acid, HNO2, follow these steps:
Step 1: Write the balanced chemical equation:
HNO2 ⇌ H+ + NO2-
Step 2: Determine the initial concentrations:
If the initial concentration of nitrous acid, HNO2, is "x," then the initial concentrations of H+ and NO2- ions are both 0 M.
Step 3: Determine the change in concentrations:
Since the balanced equation shows a 1:1:1 mole ratio between HNO2, H+, and NO2-, the change in concentration for HNO2 is -x, and for H+ and NO2- it is +x.
Step 4: Determine the equilibrium concentrations:
The equilibrium concentrations can be expressed as the initial concentrations plus the change in concentration.
For HNO2, the equilibrium concentration is: [HNO2] = x M
For H+ and NO2-, their equilibrium concentrations are: [H+] = [NO2-] = x M
Step 5: Summarize the information in an ICE table:
HNO2 ⇌ H+ + NO2-
Initial: x 0 0
Change: -x +x +x
Equilibrium: x x x
That's it! You have completed the ICE table for a solution of nitrous acid, HNO2.
To complete an ICE table for a solution of nitrous acid, HNO2, you need to follow these steps:
Step 1: Write down the balanced chemical equation representing the dissociation of nitrous acid in water:
HNO2 (aq) ⇌ H+ (aq) + NO2- (aq)
Step 2: Define the initial concentrations of the species involved in the reaction. In this case, since we are given a solution of nitrous acid, we can assume an initial concentration of [HNO2] = C. However, since nitrous acid is a weak acid, it partially dissociates, so we assume that the initial concentration of [H+] and [NO2-] is zero.
Step 3: Set up your ICE table and fill in the initial concentrations, change in concentrations, and equilibrium concentrations.
HNO2 (aq) ⇌ H+ (aq) + NO2- (aq)
-----------------------------------------------
| HNO2 | H+ | NO2- |
-----------------------------------------------
Initial | C | 0 | 0 |
Change | -x | x | x |
Equilibrium | C - x | x | x |
In the ICE table, "x" represents the change in concentration of the species. Since HNO2 dissociates to form H+ and NO2-, the concentration of HNO2 decreases by "x", while the concentration of H+ and NO2- increases by "x".
Step 4: Write down the expression for the equilibrium constant, Ka, for the reaction:
Ka = [H+][NO2-] / [HNO2]
Step 5: Substitute the equilibrium concentrations into the Ka expression. Since the equilibrium concentrations for H+ and NO2- are both "x", while the equilibrium concentration for HNO2 is C - x, the equilibrium expression becomes:
Ka = x * x / (C - x)
And that's how you complete an ICE table for a solution of nitrous acid, HNO2. Remember, once you solve for the equilibrium concentration "x", you can determine the pH of the solution by taking the negative logarithm of the H+ concentration.