Solving Equilibrium Question: Calculate Acetate Ion Concentration

In summary, the question asks for the concentration of acetate ion in a solution containing 1.00×10-3 mol of HCl and 1.90 M aqueous acetic acid. Using the equilibrium equation and taking into account the dissociation of HCl, the concentration of acetate ion is found to be approximately 5.68E-3 M.
  • #1
Jules18
102
0
Hey guys, I've tried this question a couple different ways. Please help!

Homework Statement



Calculate the concentration of the acetate ion (M) in a solution prepared by dissolving 1.00×10-3 mol of HCl(g) in 1.00 L of 1.90 M aqueous acetic acid. Ka = 1.7E-5

And at that point I'm not sure what to do.


Homework Equations



... CH3COOH --> CH3COO- + H+
initial: 1.90 M 0 0
change: - x +x +x
equlbm: ~1.9 x x

The Attempt at a Solution



I did some calculations and found that x = 5.68E-3 . I that didn't take the HCl into consideration, though - I really have no idea what to do with that. i
 
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  • #2
As you were already told at CF - concentration of H+ should account for the HCl. It is fully dissociated.

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  • #3
'm not sure how the HCl would affect the equilibrium.

I would first start by identifying the relevant equations and variables for this problem. In this case, the relevant equations are the equilibrium constant (Ka) and the dissociation of acetic acid into acetate ion and hydrogen ions. The variables we are given are the initial concentration of acetic acid (1.90 M) and the amount of HCl added (1.00×10-3 mol).

Next, I would use the equation for the dissociation of acetic acid to set up an equilibrium expression and solve for the concentration of acetate ion (x). We can ignore the HCl since it is a strong acid and will dissociate completely, meaning it will not have an effect on the equilibrium.

Based on the calculations provided, it appears that the student has correctly identified the change and equilibrium concentrations for acetic acid, acetate ion, and hydrogen ions. However, the value of x calculated does not take into account the initial concentration of acetic acid. To calculate the concentration of acetate ion, we need to add the initial concentration of acetic acid (1.90 M) to the value of x.

Once we have the value of x, we can use it to calculate the concentration of acetate ion by dividing it by the total volume of the solution (1.00 L). This will give us the final concentration of acetate ion in units of M.

In summary, to solve this equilibrium question, we need to set up an equilibrium expression, account for the initial concentration of acetic acid, and use the value of x to calculate the concentration of acetate ion. This is a common type of problem in chemistry and it is important to carefully consider all the relevant equations and variables in order to arrive at the correct solution. I hope this helps!
 

Related to Solving Equilibrium Question: Calculate Acetate Ion Concentration

1. How do I solve an equilibrium question?

To solve an equilibrium question, you need to set up an equilibrium expression based on the given chemical equation. Then, you can use the initial concentration values and the equilibrium constant to calculate the unknown concentration.

2. What is the equilibrium constant?

The equilibrium constant is a measure of the extent to which a reaction will proceed towards products at a given temperature. It is calculated by taking the ratio of the products' concentrations to the reactants' concentrations, with each concentration raised to the power of its coefficient in the balanced chemical equation.

3. What is the difference between Kc and Kp?

Kc is the equilibrium constant expressed in terms of molar concentrations, while Kp is the equilibrium constant expressed in terms of partial pressures. Kc is used for reactions in aqueous solutions, while Kp is used for reactions in gas phase.

4. How do I calculate the acetate ion concentration?

To calculate the acetate ion concentration, you need to know the equilibrium constant and the initial concentrations of all other species involved in the reaction. Then, you can use an ICE (initial, change, equilibrium) table to find the equilibrium concentration of acetate ion.

5. Can I use the Henderson-Hasselbalch equation to calculate acetate ion concentration?

Yes, you can use the Henderson-Hasselbalch equation if you know the initial concentrations of acetic acid and its conjugate base (acetate ion). However, this equation assumes that the acid dissociation constant (Ka) is known, so it may not be applicable in all cases.

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