At 25 degree celsius, what is the hyronium ion concentration in 0.100 M chloroacetate acid?
To find the hydronium ion concentration in a solution of chloroacetic acid at a given temperature, you can use the following steps:
Step 1: Write the balanced equation for the ionization of chloroacetic acid in water:
CH2ClCOOH + H2O ⇌ CH2ClCOO- + H3O+
Step 2: Calculate the initial concentration of hydronium ions in the solution. Since chloroacetic acid is a weak acid, it partially ionizes in water. For a 0.100 M solution of chloroacetic acid, you can assume that the initial concentration of hydronium ions, [H3O+], is very small compared to the initial concentration of chloroacetic acid, [CH2ClCOOH]. Therefore, you can approximate [H3O+] to be zero initially.
Step 3: Set up an equilibrium expression for the reaction:
Kw = [CH2ClCOO-][H3O+] / [CH2ClCOOH]
Since [H3O+] is negligible, you can assume that the concentration of the conjugate base ([CH2ClCOO-]) is approximately equal to the concentration of hydronium ions ([H3O+]) at equilibrium. Therefore, you can simplify the equilibrium expression:
Kw = [H3O+]^2 / [CH2ClCOOH]
Step 4: Use the ionization constant of water, Kw, to calculate the concentration of hydronium ions, [H3O+]. At 25 degrees Celsius, Kw is approximately 1.0 x 10^-14 at 25 degrees Celsius.
[H3O+]^2 / 0.100 = 1.0 x 10^-14
Step 5: Solve for [H3O+]. Taking the square root of both sides and rearranging, we get:
[H3O+] = √(1.0 x 10^-14 * 0.100)
[H3O+] = 1.0 x 10^-7 M
Therefore, at 25 degrees Celsius, the hydronium ion concentration in a 0.100 M solution of chloroacetic acid is 1.0 x 10^-7 M.
To determine the hydronium ion concentration in 0.100 M chloroacetate acid at 25 degrees Celsius, we need to consider the acid dissociation equation for chloroacetate, and its acid dissociation constant (Ka).
The dissociation equation for chloroacetic acid (CH2ClCOOH) is as follows:
CH2ClCOOH + H2O ⇌ CH2ClCOO- + H3O+
The acid dissociation constant (Ka) is a measure of the strength of an acid. In the case of chloroacetic acid, the Ka value can be found from reliable sources or experimentally determined.
Assuming we have the value for Ka, let's proceed with the calculation:
1. Start with the balanced dissociation equation: CH2ClCOOH + H2O ⇌ CH2ClCOO- + H3O+
2. Define the variables:
- [CH2ClCOOH] = 0.100 M (initial concentration of chloroacetic acid)
- [H3O+] = x (hydronium ion concentration we are trying to determine)
3. At equilibrium, the concentration of products and reactants must follow the law of mass action. Therefore, we have:
Ka = ([CH2ClCOO-] * [H3O+]) / [CH2ClCOOH]
4. Since we started with 0.100 M concentration of chloroacetic acid and it is a weak acid, we can assume that the dissociation of the acid is small compared to its initial concentration. Thus, we can assume that [CH2ClCOOH] - x ≈ [CH2ClCOOH].
5. Substitute the values into the equation and solve for x:
Ka = ([CH2ClCOO-] * [H3O+]) / [CH2ClCOOH]
Ka = (x * x) / ([CH2ClCOOH])
Ka = (x^2) / (0.100)
6. Solve the equation for x by rearranging it:
x^2 = (Ka) * (0.100)
x = √(Ka * 0.100)
The value of Ka can be obtained from trusted sources, such as textbooks or online databases for organic acids like chloroacetic acid. Once you have the value of Ka, substitute it into the equation to find the value of x, which corresponds to the hydronium ion concentration in the chloroacetate acid solution at 25 degrees Celsius.
If we shorten chloroacetic acid to HC, then
..........HC ==> H^+ + C^-
initial...0.100M..0.....0
change.....-x......x.....x
equil....0.100-x....x....x
Ka = (H^+)(C^-)/(HC)
Look up Ka, substitute from the ICE chart above and solve for H^+.