Calulations and observations to determine the molarity of given sodium hydroxide solution provided with M/20 oxalic acid solution
I think I would measure a precise volume of the oxalic solution of known molarity.
Then, titrate it with the NaOH solution, measuring the pH (or using an indicator in the acid). Keep Note the final volume, subtract the initial volume of the acid, and then, you know the volume of the NaOH, and using your titration equation, calculate Molarity of NaOH solution
To determine the molarity of a given sodium hydroxide (NaOH) solution using a M/20 oxalic acid (H2C2O4) solution, you will need to perform a titration experiment. Here are the steps you can follow:
1. Prepare the M/20 oxalic acid solution: Start by calculating the required amount of oxalic acid needed to make a M/20 solution. M/20 means one-twentieth of a molar concentration. For example, if you want to make 1 liter of the solution, you would need (1/20) * 0.1 moles of oxalic acid (0.1 moles being the molar mass of oxalic acid). Dissolve the calculated amount of oxalic acid in distilled water and make up the solution to the desired volume, usually 1 L.
2. Standardize the oxalic acid solution: To ensure the accuracy of the oxalic acid solution, it needs to be standardized against a primary standard substance, such as sodium carbonate (Na2CO3) or potassium hydrogen phthalate (KHP). You can find the detailed procedure for standardizing the oxalic acid solution using these primary standards in chemistry textbooks or laboratory manuals.
3. Setup the titration experiment: Once the oxalic acid solution is standardized, you can proceed with the titration experiment. Take a known volume, let's say V1, of the standardized oxalic acid solution using a pipette and transfer it to a clean conical flask.
4. Add an indicator: To make the color change during the titration visible, add a few drops of a suitable acid-base indicator to the conical flask. Phenolphthalein is commonly used for this purpose. It changes from colorless to pinkish at the end point of the titration.
5. Titrate with sodium hydroxide solution: Slowly add the sodium hydroxide solution from a burette into the conical flask containing the oxalic acid solution while swirling the flask. The sodium hydroxide reacts with the oxalic acid, forming water and sodium oxalate. The reaction can be represented as follows:
H2C2O4 + 2NaOH → Na2C2O4 + 2H2O
Continue adding the sodium hydroxide solution until the color of the indicator changes permanently, from colorless to a faint pink shade. The color change signifies that all the oxalic acid has reacted with the sodium hydroxide solution.
6. Record the initial and final burette readings: Note down the initial burette reading (the volume of sodium hydroxide solution at the start of the titration) and the final burette reading (the volume of sodium hydroxide solution used to reach the end point).
7. Perform calculations: To calculate the molarity of the sodium hydroxide solution (M2), use the balanced equation and stoichiometry of the reaction to determine the moles of oxalic acid used:
Moles of oxalic acid (H2C2O4) = M1 * V1
Where M1 is the molarity of the standardized oxalic acid solution and V1 is the volume of oxalic acid solution used in the titration.
Then, using the balanced equation, determine the moles of sodium hydroxide used:
Moles of sodium hydroxide (NaOH) = Moles of oxalic acid / 2
Finally, calculate the molarity of the sodium hydroxide solution:
Molarity of NaOH (M2) = Moles of sodium hydroxide (NaOH) / Volume of sodium hydroxide solution used
Make sure to convert volumes to liters and adjust the calculations accordingly.
By following these steps and performing the necessary calculations, you can determine the molarity of the given sodium hydroxide solution using the M/20 oxalic acid solution.