In lab, I weighed out and found the molarity of 1.108g Na2C2O4 and 1.100g K3Fe(C2O4)3. I titrated an average of 0.0335L of the sodium oxalate solution with KMnO4(potassium permanganate). I then titrated an average of 0.0169L of K3Fe(C2O4)3 X 3H2O with potassium permanganate. I used 2MnO4 + 6H + 5H2C2O4 = 8H2O + 2Mn + 10CO2 for the first stoichiometry part to find out the moles of permanganate ion. I then used 5Fe(C2O4)3 + 6MnO4 + 48H = 5Fe + 6Mn + 30 CO2 + 24 H2O. For the second stoichiometry part to find out the number of moles of K3Fe(C2O4)3. I tried this several different ways, but what I can come up with is that I used the moles/L of sodium oxalate and since the sodium oxalate solution is the same as the oxalic acid which is used in the first formula to find the moles of the permanganate ion which is used in the second formula to find the number of moles of K3Fe(C2O4)3 I reacted.I don't understand and don't know why I have to use my average titrated volumes. Please help. I have reread the lab so many times I cannot wrap my mind around it
Your question is somewhat lengthy and sorta runs in circles; however, I assume the question boils down to why are you using the average. I think the answer is this.
You may use individual titrations, calculate EACH run for molarity (or whatever you're calculating) and after running say four of these you calculate the average M of the solution. OR you can take the average volume of the titrations and do ONE calculation to find the average M of the solution. I think the idea is that by using the average volume you can save some calculation time.
It seems like you are trying to understand the calculations involved in a lab experiment where you performed titrations of sodium oxalate (Na2C2O4) and potassium ferric oxalate (K3Fe(C2O4)3) using potassium permanganate (KMnO4). Let's break down the steps and try to understand them:
1. Weighing and finding the molarity of the substances:
- You started by weighing out 1.108g of Na2C2O4 and 1.100g of K3Fe(C2O4)3.
- To find the molarity of the solutions, you would need to calculate the number of moles of the substances.
- The molarity (M) is given by the formula: M = moles/volume (in liters).
- Knowing the mass and molar mass of the substances, you can calculate the number of moles using the equation: moles = mass/molar mass.
2. Titrating the sodium oxalate solution:
- For the first part of the experiment, you titrated an average of 0.0335L of the sodium oxalate solution.
- You used the balanced chemical equation 2MnO4 + 6H+ + 5H2C2O4 = 8H2O + 2Mn + 10CO2 to determine the stoichiometry between MnO4- and H2C2O4.
- By using the stoichiometry, you can convert the moles of permanganate ion (MnO4-) consumed in the reaction to moles of sodium oxalate (Na2C2O4) present in the solution.
- This will allow you to calculate the molarity of the sodium oxalate solution.
3. Titrating the potassium ferric oxalate solution:
- In the second part of the experiment, you titrated an average of 0.0169L of K3Fe(C2O4)3 X 3H2O solution.
- You used the balanced chemical equation 5Fe(C2O4)3 + 6MnO4- + 48H+ = 5Fe + 6Mn + 30CO2 + 24H2O to determine the stoichiometry between Fe(C2O4)3 and MnO4-.
- Again, using stoichiometry, you can convert the moles of permanganate ion (MnO4-) consumed in the reaction to moles of the potassium ferric oxalate (K3Fe(C2O4)3) present in the solution.
- This will allow you to calculate the molarity of the potassium ferric oxalate solution.
Using the average titrated volumes helps ensure the accuracy of your calculations. We use averages to reduce any potential errors or discrepancies that might have occurred during the titration process. Taking multiple measurements allows you to account for any variability in the experimental results and obtain a more reliable value for the molarity.
If you still have specific questions or need further clarification on any step, please let me know!