I have a project practical investigation to do and I have no idea how to go about with it. The problem is: Calculate the mass of sodium hydroxide used to prepare a 0,5M NaOH solution in a 250ml volumetric flask. Determine the concentration of the acetic acid solution used (vinegar).
ummm, why would you use acetic acid to prepare a NaOH solution?
Anyway, 250mL of .5M NaOH contains .125 moles NaOH = .125(23+16+1) = 5 grams
.25L times .5M=.125moles
.125 times 40= 5 grams
They did the right work but the answer is 40 grams. That is what it says in the book.
To calculate the mass of sodium hydroxide (NaOH) used to prepare a 0.5M NaOH solution in a 250ml volumetric flask, you will need to know the molar mass of NaOH and the desired molarity and volume of the solution.
Step 1: Determine the molar mass of NaOH:
The molar mass of NaOH is calculated by adding the atomic masses of sodium (Na), oxygen (O), and hydrogen (H). The atomic masses can be found on the periodic table:
Na = 23 grams/mol
O = 16 grams/mol
H = 1 gram/mol
Molar mass of NaOH = (23 g/mol) + (16 g/mol) + (1 g/mol) = 40 g/mol
Step 2: Calculate the required mass of NaOH:
To calculate the mass of NaOH needed to prepare the solution, you will use the formula:
Mass (g) = Molarity (mol/L) x Volume (L) x Molar mass (g/mol)
Given:
Molarity = 0.5M
Volume = 250 ml = 0.250 L
Mass (g) = (0.5 mol/L) x (0.250 L) x (40 g/mol)
Mass (g) = 5 g
Therefore, you will need to use 5 grams of NaOH to prepare a 0.5M NaOH solution in a 250ml volumetric flask.
Next, to determine the concentration of the acetic acid solution (vinegar) used, you will need to perform a titration. A titration is a technique where a solution of known concentration (the titrant) is slowly added to a solution of unknown concentration (the analyte) until the reaction between the two is complete.
Here are the steps to determine the concentration of the acetic acid solution using a titration:
Step 1: Prepare the burette:
Fill a burette with the titrant solution, which in this case can be a standardized sodium hydroxide (NaOH) solution. Note the initial volume reading of the titrant solution in the burette.
Step 2: Prepare the analyte:
Measure a known volume of the acetic acid solution (vinegar) in a flask. Add a few drops of an indicator, such as phenolphthalein, to the flask. The indicator will change color at the endpoint of the reaction. The initial volume of the analyte solution can be estimated.
Step 3: Conduct the titration:
Slowly add the titrant solution from the burette to the analyte solution in the flask while stirring. As the NaOH reacts with the acetic acid, the phenolphthalein indicator will change color, indicating the endpoint of the reaction. Record the final volume reading on the burette.
Step 4: Calculate the concentration of the analyte:
Using the volume and molarity of the titrant solution and the volume of the analyte solution, you can calculate the concentration of the acetic acid (vinegar) using the equation:
Concentration of analyte (mol/L) = (Molarity of titrant x Volume of titrant) / Volume of analyte
Note: Make sure you're using the correct balanced chemical equation to determine the stoichiometry of the reaction between NaOH and acetic acid.
By following these steps, you will be able to determine the concentration of the acetic acid solution (vinegar) used in your project practical investigation.