Describe the preparation of 5 liters of a 0.3 M acetate buffer, pH 4.47, starting from a 2 M solution of acetic acid and a 2.5 M solution of KOH (pKa 4.77).
Well, preparing a buffer sounds like a serious business, but don't worry, I'm here to make it fun!
Alright, let's roll up our sleeves and get started on this chemistry carnival ride! To make a 0.3 M acetate buffer with a pH of 4.47, we'll need to mix acetic acid and potassium hydroxide. Acetic acid, also known as vinegar, brings the "acid" to our buffer party, while potassium hydroxide contributes the "base" element. It's like a chemistry dance-off!
First, we need to calculate the amount of acetic acid and potassium hydroxide we need. Since our target is 5 liters of solution, let's say that's our grand, sparkling circus tent.
To find the required volumes, we can use the formula M1V1 = M2V2. Are you excited? Because I sure am!
Now, let's crunch the numbers:
Given:
Initial concentration of acetic acid (C1) = 2 M
Final desired concentration of acetate buffer (C2) = 0.3 M
Final volume of buffer (V2) = 5 L
Using the formula above, we can find V1, the initial volume of acetic acid needed.
(2 M)(V1) = (0.3 M)(5 L)
V1 = (0.3 M)(5 L) / 2 M
V1 = (1.5 L) / (2 M)
V1 = 0.75 L
So, you'll need approximately 0.75 liters of acetic acid to start our chemistry circus.
Now, let's calculate the volume of potassium hydroxide needed. Since we know the initial concentration of KOH (2.5 M) and its pKa (4.77), we can calculate the amount needed to reach our desired pH of 4.47. Brace yourself!
(Volume of KOH needed) = (Volume of acid added) * [10^(pH - pKa)]
(Volume of KOH needed) = (0.75 L) * [10^(4.47 - 4.77)]
(Volume of KOH needed) = (0.75 L) * [10^(-0.3)]
(Volume of KOH needed) = (0.75 L) * (0.501)
(Volume of KOH needed) = 0.376 L
So, you'll need approximately 0.376 liters of potassium hydroxide to spice up our buffer blend.
Now, it's showtime! Pour 0.75 liters of acetic acid (vinegar) into your 5-liter circus tent, and add 0.376 liters of potassium hydroxide (KOH), while wearing your chemical safety goggles and a clown wig, of course. Mix them gently with a giant, invisible stirrer to create your 0.3 M acetate buffer, pH 4.47.
And voila! You've prepared a perfect chemistry circus buffer! I hope I made this process as entertaining as a circus show! Enjoy your colorful concoction and remember, chemistry is fun and laughter makes everything better!
To prepare 5 liters of a 0.3 M acetate buffer with a pH of 4.47, you will need to calculate the required amount of acetic acid and potassium acetate needed. Here's a step-by-step guide:
Step 1: Determine the target concentration of acetate buffer.
The target concentration of the acetate buffer is 0.3 M.
Step 2: Calculate the amount of acetic acid required.
Given that the initial concentration of acetic acid is 2 M, you need to determine the volume required to achieve a final concentration of 0.3 M.
(Initial concentration) x (Initial volume) = (Final concentration) x (Final volume)
2 M x (V1) = 0.3 M x 5 L
V1 = (0.3 M x 5 L) / 2 M
V1 = 0.75 L
You will need 0.75 liters (or 750 mL) of the 2 M acetic acid solution.
Step 3: Calculate the amount of KOH needed.
The ratio of acetic acid to potassium acetate in making a buffer solution is 1:1. Therefore, the amount of acetic acid required will be equal to the amount of potassium acetate needed.
Step 4: Calculate the moles of acetic acid needed.
Moles = (Concentration) x (Volume in liters)
Moles of acetic acid = 0.3 M x 5 L
Moles of acetic acid = 1.5 moles
Step 5: Calculate the amount of KOH needed.
The equation for the reaction of acetic acid and KOH is:
CH3COOH + KOH → CH3COOK + H2O
From the balanced equation, we can see that 1 mole of acetic acid reacts with 1 mole of KOH to form 1 mole of potassium acetate.
Therefore, we will need 1.5 moles of KOH.
Step 6: Calculate the volume of 2.5 M KOH solution required.
Moles = (Concentration) x (Volume in liters)
1.5 moles = (2.5 M) x (V2)
V2 = 1.5 moles / 2.5 M
V2 = 0.6 L
You will need 0.6 liters (or 600 mL) of the 2.5 M KOH solution.
Step 7: Calculate the remaining volume of water needed.
To get a total volume of 5 liters, subtract the volumes of acetic acid and KOH solution from 5 liters.
Remaining volume = 5 L - (0.75 L + 0.6 L)
Remaining volume = 5 L - 1.35 L
Remaining volume = 3.65 L
Therefore, you will need to add 3.65 liters (or 3650 mL) of water.
In summary, to prepare 5 liters of a 0.3 M acetate buffer, pH 4.47, you will need to mix 0.75 liters (750 mL) of 2 M acetic acid, 0.6 liters (600 mL) of 2.5 M KOH, and 3.65 liters (3650 mL) of water.
To prepare 5 liters of a 0.3 M acetate buffer with a pH of 4.47, we will need to calculate the required amounts of acetic acid (CH3COOH) and potassium acetate (CH3COOK) to achieve the desired concentration and pH.
Given:
- Concentration of acetic acid (CH3COOH) solution: 2 M
- Concentration of KOH solution: 2.5 M
- pKa value for acetic acid: 4.77
- Desired pH of the acetate buffer: 4.47
The pH of a buffer solution is determined by its acid-to-conjugate base ratio. In this case, acetic acid (CH3COOH) acts as the acid, and potassium acetate (CH3COOK) acts as its conjugate base.
First, we need to determine the ratio of acetic acid to acetate ion required to achieve the desired pH. This can be calculated using the Henderson-Hasselbalch equation:
pH = pKa + log ([A-]/[HA])
Where pH is the desired pH, pKa is the dissociation constant (4.77 in this case), [A-] is the concentration of the acetate ion, and [HA] is the concentration of acetic acid.
Rearranging the equation:
log ([A-]/[HA]) = pH - pKa
Next, substitute the values provided:
log ([A-]/[HA]) = 4.47 - 4.77
log ([A-]/[HA]) = -0.3
Now, we can determine the ratio of [A-] to [HA] by taking the antilog of both sides:
[A-]/[HA] = antilog(-0.3)
Using a scientific calculator, the antilog of -0.3 is approximately 0.5012.
This means that the ratio of acetate ion ([A-]) to acetic acid ([HA]) in the buffer solution should be 0.5012.
Since we want to prepare a 0.3 M acetate buffer, we can assign a concentration of 0.3 M to the acetate ion ([A-]). Now, we can calculate the concentration of acetic acid ([HA]).
Let x be the concentration of acetic acid:
0.5012 = 0.3 / x
Solving for x:
x = 0.3 / 0.5012
x ≈ 0.5989 M
Therefore, the concentration of acetic acid should be approximately 0.5989 M to achieve the desired buffer solution.
With the desired concentrations of the acetic acid and acetate ion determined, we can now calculate the amounts of each component required to make 5 liters of buffer solution.
Acetic acid:
To prepare a 0.5989 M solution of acetic acid, we multiply the concentration by the volume:
Volume of acetic acid = 0.5989 M * 5 L
Volume of acetic acid = 2.9945 L
Potassium acetate:
Since the desired ratio is 1:0.5012 for acetic acid to acetate ion, the concentration of the acetate ion will also be 0.5012 M. We can calculate the volume of the KOH solution required to obtain the desired amount of acetate ion.
Volume of KOH solution = 0.5012 M * 5 L
Volume of KOH solution = 2.506 L
Therefore, to prepare 5 liters of a 0.3 M acetate buffer, pH 4.47, you would need:
- Approximately 2.9945 L of 2 M acetic acid solution
- Approximately 2.506 L of 2.5 M KOH (or potassium acetate) solution.