Susie is instructed to prepare 400mL of a 0.3M acetate buffer of pH=4.44, and she is given sodium acetate trihydrate and glacial acetate acid (99% by weight, density=1.05 g/mL0. Susie can't figure out what to do! How should she prepare this buffer? Acetic acid, Ka=1.8x10^-5

To prepare a 0.3M acetate buffer with a pH of 4.44, Susie can follow these steps:

Step 1: Calculate the ratio of acetic acid (CH3COOH) to sodium acetate (CH3COONa) required for a buffer of pH 4.44.

The Henderson-Hasselbalch equation can be used to determine the ratio of the conjugate acid-base pairs in a buffer solution:

pH = pKa + log([A-]/[HA])

Given that the pH is 4.44 and the pKa is given as 1.8x10^-5, we can rearrange the equation to solve for [A-]/[HA]:

4.44 = -log([A-]/[HA]) + log(1/[A-])

Therefore, [A-]/[HA] = 10^(pH - pKa) = 10^(4.44 - (-log(1.8x10^-5)))

Step 2: Determine the required amounts of sodium acetate (CH3COONa) and acetic acid (CH3COOH) to prepare the buffer.

To calculate the moles of sodium acetate required, use the formula:

moles of CH3COONa = volume of buffer (in L) * molarity of CH3COONa

moles of CH3COOH = volume of buffer (in L) * molarity of CH3COOH

Step 3: Convert moles of sodium acetate and acetic acid to grams.

Since Susie is given the density of glacial acetic acid, she can determine the volume required to give 400 mL of acetic acid. From that, she can calculate the mass of acetic acid required using its density.

Step 4: Dissolve the calculated mass of sodium acetate in water, and then slowly add the calculated mass of glacial acetic acid while monitoring the pH.

After preparing the solutions, Susie can start by dissolving the calculated mass of sodium acetate trihydrate (CH3COONa·3H2O) in an appropriate volume of water to make a solution. Once dissolved, she can use a pH meter or pH paper to measure the pH and adjust if necessary by adding small amounts of glacial acetic acid. The solution should be mixed thoroughly after each addition.

It's important to note that glacial acetic acid is highly corrosive and should be handled with caution. Susie may want to wear protective gloves and eyewear while handling it.

Remember to always double-check your calculations and be cautious when handling chemicals. If unsure, it's always recommended to consult a chemistry teacher or professional for guidance.