Preparation of M/20 oxalic acid solution and determine it strength. For practical
How much do you want to prepare? Say 100 mL. Then
mols oxalic acid needed = M x L = 0.05 M x 0.1 L = ?
Then grams = mols x molar mass = ?
Google how to determine the strength of oxalic acid. The easy way is to titrate it with a standard solution of a base.
To prepare a M/20 oxalic acid solution and determine its strength, follow these steps:
1. First, calculate the amount of oxalic acid needed to make the solution. M/20 means one-twentieth of a molar concentration. Since the molar mass of oxalic acid (H2C2O4) is 90.03 g/mol, M/20 concentration would be (1/20) x 90.03 g = 4.5015 g.
2. Weigh out 4.5015 grams of oxalic acid using a digital balance. Use a weighing boat or container to prevent spillage.
3. Transfer the measured oxalic acid into a clean and dry 1-liter volumetric flask.
4. Add distilled water to the flask to make up the volume to 1 liter. Use a clean glass rod to stir the solution until the oxalic acid is completely dissolved.
5. Once the solution is prepared, it is important to determine the actual strength of the M/20 oxalic acid solution. This can be done by titrating it against a standard solution of sodium hydroxide (NaOH).
6. Make sure the burette and pipette are clean and calibrated for accurate measurements.
7. Pipette 25 mL of the M/20 oxalic acid solution into a clean conical flask.
8. Slowly add drops of phenolphthalein indicator to the conical flask. The indicator will turn pink in the presence of excess acid.
9. Fill the burette with standardized 0.1 M NaOH solution.
10. Start the titration by slowly adding the NaOH solution from the burette to the oxalic acid solution while constantly swirling the flask. The pink color will eventually fade as the base neutralizes the acid.
11. When the pink color just disappears, record the volume of NaOH solution used.
12. Repeat the titration process for accuracy until you get consistent results.
13. Calculate the actual strength of the M/20 oxalic acid solution using the titration data. The balanced chemical equation for the reaction between oxalic acid and sodium hydroxide is:
H2C2O4 + 2NaOH → Na2C2O4 + 2H2O
Using stoichiometry, you can determine the number of moles of oxalic acid from the volume of NaOH solution used. Then, calculate the molarity of the oxalic acid solution.
Note: Always use appropriate safety measures, such as wearing protective gloves and goggles, when handling chemicals.
To prepare a M/20 oxalic acid solution and determine its strength practically, follow these steps:
1. Calculate the required amount of oxalic acid:
- Determine the molar mass of oxalic acid, which is C2H2O4 (2 carbon atoms + 2 hydrogen atoms + 4 oxygen atoms).
- Multiply the molar mass by the desired concentration, M/20 (Molar/20), to find the required grams of oxalic acid.
2. Weigh the calculated amount of oxalic acid:
- Use an analytical balance to accurately measure the required grams of oxalic acid.
3. Dissolve the oxalic acid in distilled water:
- Take a beaker and add a small amount of distilled water to it.
- Gradually add the measured oxalic acid to the beaker while stirring until it completely dissolves.
- Then, transfer the solution to a volumetric flask.
4. Dilute to the required volume:
- Add distilled water to the volumetric flask until it reaches the calibration mark (usually indicated on the neck of the flask).
- Stopper the flask and mix the solution thoroughly by inverting it several times.
To determine the strength of the M/20 oxalic acid solution practically, you will need a standardized solution of sodium hydroxide (NaOH) and a suitable indicator (phenolphthalein).
5. Set up a titration experiment:
- Take a set amount (about 25 mL) of the prepared oxalic acid solution using a pipette and transfer it to a conical flask.
- Add a few drops of phenolphthalein indicator to the conical flask.
6. Titration:
- Fill a burette with the standardized sodium hydroxide solution.
- Gradually add the NaOH solution from the burette to the conical flask containing the oxalic acid solution, while stirring continuously.
- The phenolphthalein indicator will change color from colorless to pale pink once the acid has been neutralized.
7. Note the volume of sodium hydroxide solution used:
- Read the initial and final burette readings to determine the volume of NaOH solution that was required to neutralize the oxalic acid.
8. Calculate the strength of the oxalic acid solution:
- Use the volume of NaOH solution consumed in the titration and its known concentration to calculate the molarity (strength) of the oxalic acid solution.
- The ratio of the volume and concentration of NaOH to the volume of oxalic acid used in the titration will give you the molarity of the oxalic acid solution.
Following these steps will help you prepare a M/20 oxalic acid solution and determine its strength practically through titration using a standardized solution of sodium hydroxide.