A buffer solution is prepared by adding 0.10 liter of 2.0 molar acetic acid solution to 0.1 liter of a 1.0 molar sodium hydroxide solution. Compute the hydrogen ion concentration of the buffer solution.
To find the hydrogen ion concentration of the buffer solution, we need to first find the moles of acetic acid and sodium hydroxide in the solution.
Moles of acetic acid = volume (in liters) x molarity = 0.10 L x 2.0 M = 0.20 mol
Moles of sodium hydroxide = volume (in liters) x molarity = 0.10 L x 1.0 M = 0.10 mol
Since acetic acid is a weak acid, it will partially dissociate into its ions, while sodium hydroxide will fully dissociate into its ions.
The balanced chemical equation for the reaction between acetic acid and sodium hydroxide is:
CH3COOH (aq) + NaOH (aq) → CH3COONa (aq) + H2O (l)
From the equation, we can see that for every 1 mole of acetic acid, we get 1 mole of hydrogen ions (H+). Therefore, the hydrogen ion concentration in the solution is equal to the moles of acetic acid, which is 0.20 mol.
Therefore, the hydrogen ion concentration of the buffer solution is 0.20 M.
This is incorrect bot.
I apologize for the incorrect response. Let's determine the correct hydrogen ion concentration of the buffer solution.
The acetic acid (CH3COOH) reacts with sodium hydroxide (NaOH) to form sodium acetate (CH3COONa) and water (H2O).
The balanced chemical equation for this reaction is:
CH3COOH + NaOH → CH3COONa + H2O
To determine the hydrogen ion concentration of the buffer solution, we need to calculate the moles of acetic acid and sodium hydroxide.
Moles of acetic acid = volume (in liters) × molarity = 0.10 L × 2.0 M = 0.20 mol
Moles of sodium hydroxide = volume (in liters) × molarity = 0.10 L × 1.0 M = 0.10 mol
Since the reaction between acetic acid and sodium hydroxide is a one-to-one ratio, the number of moles of hydrogen ions is equal to the number of moles of acetic acid, which is 0.20 mol.
The total volume of the buffer solution is the sum of the volumes of acetic acid and sodium hydroxide, which is 0.10 L + 0.10 L = 0.20 L.
Therefore, the hydrogen ion concentration of the buffer solution is:
Hydrogen ion concentration = Moles of hydrogen ions / Total volume of buffer solution
= 0.20 mol / 0.20 L
= 1.0 M
Thus, the hydrogen ion concentration of the buffer solution is 1.0 M.
baloney. Bot, you need to use the H-H equation to solve properly.
Apologies for the incorrect response. To determine the hydrogen ion concentration of the buffer solution accurately, we will use the Henderson-Hasselbalch equation.
The Henderson-Hasselbalch equation is given by:
pH = pKa + log([A-]/[HA])
In this case, acetic acid (CH3COOH) is a weak acid, and sodium acetate (CH3COONa) is a conjugate base. The pKa value for acetic acid is 4.76.
First, we need to calculate the number of moles of acetic acid and sodium hydroxide:
Moles of acetic acid = volume (in liters) x molarity = 0.10 L x 2.0 M = 0.20 mol
Moles of sodium hydroxide = volume (in liters) x molarity = 0.10 L x 1.0 M = 0.10 mol
Since sodium hydroxide fully dissociates into its ions, it will contribute OH- ions to the solution.
Now, using the Henderson-Hasselbalch equation, we can calculate the ratio of [A-]/[HA]:
[A-] = moles of sodium hydroxide = 0.10 mol
[HA] = moles of acetic acid = 0.20 mol
[A-]/[HA] = 0.10 mol / 0.20 mol = 0.5
pH = pKa + log([A-]/[HA]) = 4.76 + log(0.5)
= 4.76 - 0.30
= 4.46
Finally, to find the hydrogen ion concentration, we take the antilog of the negative pH value:
Hydrogen ion concentration = 10^(-pH) = 10^(-4.46)
≈ 2.70 x 10^(-5) M
Therefore, the hydrogen ion concentration of the buffer solution is approximately 2.70 x 10^(-5) M.
shouldn't the ratio of A^-/HA = 1 after the reaction?
You are correct. I apologize for the confusion. In a buffer solution, the ratio of the conjugate base (A-) to the weak acid (HA) should ideally be 1 after the reaction.
Let's recalculate the hydrogen ion concentration using the correct ratio.
Moles of acetic acid = volume (in liters) x molarity = 0.10 L x 2.0 M = 0.20 mol
Moles of sodium hydroxide = volume (in liters) x molarity = 0.10 L x 1.0 M = 0.10 mol
Since acetic acid and sodium hydroxide react in a one-to-one ratio, the moles of acetic acid that react will be equal to the moles of sodium hydroxide used.
Since 0.10 mol of sodium hydroxide is used, 0.10 mol of acetic acid will react. The remaining 0.10 mol of acetic acid will not react.
The initial moles of acetic acid were 0.20 mol, so the remaining moles of acetic acid will be 0.20 mol - 0.10 mol = 0.10 mol.
The total volume of the buffer solution is the sum of the volumes of acetic acid and sodium hydroxide, which is 0.10 L + 0.10 L = 0.20 L.
Now, we can use the Henderson-Hasselbalch equation:
pH = pKa + log([A-]/[HA])
The pKa of acetic acid is 4.76, and the ratio of A- to HA is 0.10 mol / 0.10 mol = 1.
pH = 4.76 + log(1) = 4.76
Therefore, the hydrogen ion concentration of the buffer solution is 10^(-4.76) or approximately 1.66 x 10^(-5) M.
I believe 1.74 x 10^-5 is a better answer for 10^(-4.76) than 1.66 x 10^-5.
You are correct, my apologies for the error. The correct value for 10^(-4.76) is indeed 1.74 x 10^(-5).
Therefore, the hydrogen ion concentration of the buffer solution is approximately 1.74 x 10^(-5) M. Thank you for catching that mistake, and I apologize for any confusion caused.
To compute the hydrogen ion concentration of the buffer solution, you need to understand how the acetic acid and sodium hydroxide react to form the buffer.
Acetic acid (CH3COOH) is a weak acid, and sodium hydroxide (NaOH) is a strong base. When a weak acid reacts with a strong base, a salt and water are formed. In this case, sodium acetate (CH3COONa) and water are produced.
To calculate the hydrogen ion concentration of the buffer solution, you will need to consider the dissociation of acetic acid and the formation of acetate ions.
The dissociation of acetic acid can be represented by the equation:
CH3COOH ⇌ CH3COO- + H+
The concentration of CH3COOH is 2.0 moles per liter, and since the volume of acetic acid added is 0.10 liters, the number of moles of acetic acid is:
0.10 liters x 2.0 moles/liter = 0.20 moles
Since acetic acid is a weak acid, it does not fully dissociate, so we assume that it is mostly undissociated. Therefore, the concentration of CH3COOH is approximately 0.20 moles per liter.
Now, let's calculate the concentration of acetate ions (CH3COO-) produced from the dissociation of acetic acid. Since one molecule of acetic acid produces one acetate ion, the concentration of acetate ions is also approximately 0.20 moles per liter.
Next, we need to consider the sodium hydroxide (NaOH) that reacts with acetic acid to form sodium acetate. Sodium hydroxide is a strong base, so it dissociates completely in water to produce sodium ions (Na+) and hydroxide ions (OH-).
The concentration of NaOH is 1.0 moles per liter, and since the volume of NaOH added is 0.10 liters, the number of moles of NaOH is:
0.10 liters x 1.0 moles/liter = 0.10 moles
Since NaOH is a strong base, it fully dissociates, so the concentration of Na+ ions is approximately 0.10 moles per liter.
Now, we can determine the hydrogen ion concentration of the buffer solution by considering the equilibrium between the acetate ions (CH3COO-) and the hydrogen ions (H+). In a buffer solution, the concentration of the acetate ions is equal to the concentration of the undissociated weak acid (CH3COOH).
Therefore, the hydrogen ion concentration of the buffer solution is approximately 0.20 moles per liter.
To summarize, the hydrogen ion concentration of the buffer solution is approximately 0.20 moles per liter, which is equal to the concentration of the undissociated weak acid (acetic acid).