Common Titration Errors and How They Can Affect Results

In summary, during a titration lab to determine the weight percent of CO3^2- in an unknown sample containing only NaCl and CaCO3^2-, the results showed a ~10% difference between the first and second titration. Some possible sources of error were identified, including inaccurate buret readings and poor mixing when preparing the HCl and NaOH solutions. However, the difference in the amount of unknown and the use of different volumes of HCl for each replicate may have also contributed to the discrepancy. More careful consideration and analysis of all potential sources of error is needed to determine the cause of the ~10% difference.
  • #1
higherme
129
0
I did a titration lab to find out the weight percent of CO3^2- in an unknown sample which contains only NaCL and CaCO3^2-.

My results were about 29% for the first titration and 18% for the second titration; I was wondering the types of error that led to this ~10% difference.

Some of the errors I thought of are:
- The buret readings were not very accurate.
- When preparing the 1 L of 0.01M HCl from 6M HCl (dilution) the 6M HCl was not mixed well with water. (used to dissolve the unknown)
- Same for the 1L of 0.01M NaOH from 6M NaOH which was used to titrate the unknown
 
Physics news on Phys.org
  • #2
What volume of titrant did you use? I'll assume roughly 20 mL. You would have to misread the buret by 2 mL for this to be the source of your error.

- When preparing the 1 L of 0.01M HCl from 6M HCl (dilution) the 6M HCl was not mixed well with water. (used to dissolve the unknown)
The poor preparation of the HCl would give you an error of accuracy, not precision. This problem deals with an error of precision.

Why don't you assume that the solutions you used in both replicates was identical. What could have caused you this error under that assumption?
 
  • #3
"Why don't you assume that the solutions you used in both replicates was identical. What could have caused you this error under that assumption?"

i don't get what is meant here~
 
  • #4
well the amount of unknown i used for both replicates were pretty much around the same weight... just 0.001g difference... would that matter?

well... the amount of HCl used to dissolve the first sample is 21.31ml and 25.47ml for the second sample... maybe the error is there??

is that kind of right?? :P
 
  • #5
Describe the solid material you used (NaCl + CaCO3). Was it a fine powder or were there larger grains apparent? Describe your titration endpoint. Were both replicates identical in color. Was the color dark or light? What indicator did you use?
 
  • #6
higherme said:
"Why don't you assume that the solutions you used in both replicates was identical. What could have caused you this error under that assumption?"

i don't get what is meant here~

I meant that you should assume that the concentration of HCl used in both replicates was identical and that the concentration of NaOH used in both replicates was identical. Insufficient mixing when diluting these reagents is possible but how likely is it? Did you at least try to mix the individual solutions?
 

What is titration and why is it important in scientific research?

Titration is a laboratory technique used to determine the concentration of a substance in a solution. It involves adding a known solution of one substance (called the titrant) to a known volume of another substance until the reaction between the two is complete. Titration is important in scientific research because it allows for precise and accurate measurements of concentrations, which are crucial for conducting experiments and analyzing data.

What are some common titration errors that can occur during an experiment?

Some common titration errors include inaccurate measurements of the titrant or the substance being titrated, improper calibration of equipment, inadequate mixing of solutions, and human error in recording data or performing calculations.

How can titration errors affect the results of an experiment?

Titration errors can significantly impact the accuracy and precision of the results of an experiment. Inaccurate measurements or improper calibration can lead to incorrect concentration calculations, while inadequate mixing can result in incomplete reactions and incorrect endpoint determinations. Human error in recording data or performing calculations can also lead to incorrect results.

How can scientists prevent or minimize titration errors?

To prevent or minimize titration errors, scientists should ensure they are using properly calibrated equipment and accurately measuring the substances being used. They should also mix solutions thoroughly and carefully record data and perform calculations. It is also important to repeat titrations multiple times and calculate the average result to minimize the impact of any individual errors.

What steps can be taken to correct for titration errors if they occur?

If titration errors occur, scientists can take steps to correct them by repeating the titration and calculating the average result, checking for proper equipment calibration, and ensuring accurate measurements of substances. They can also consult with colleagues or refer to established protocols for troubleshooting common titration errors.

Similar threads

Solve Backtitration Problem: Find mL of NaOH Used
    • Biology and Chemistry Homework Help
Replies
1
Views
3K
How to prepare 0.1M 200mL HCl Solution using 6M HCl
    • Biology and Chemistry Homework Help
Replies
2
Views
9K
Determine amount of base to use for titration?
    • Biology and Chemistry Homework Help
Replies
1
Views
2K
Rinsing Errors in Back Titration (Finding Nitrogen in Fertiliser)?
    • Biology and Chemistry Homework Help
Replies
1
Views
5K
How Can You Accurately Separate and Quantify Components in a Mixed Sample Lab?
    • Biology and Chemistry Homework Help
Replies
1
Views
3K
Titration Laboratory Help
    • Biology and Chemistry Homework Help
Replies
1
Views
2K
What is the Percent Oxalic Acid Dihydrate in an Unknown Sample?
    • Biology and Chemistry Homework Help
Replies
5
Views
4K
Quantitative Titration - NaOH and HCl
    • Biology and Chemistry Homework Help
Replies
9
Views
26K
Solve Back Titration Problem to Find Ammonium Sulfate Mass in Fertiliser
    • Biology and Chemistry Homework Help
Replies
2
Views
3K
Determining Concentration of H2SO4 in Diluted Solution
    • Biology and Chemistry Homework Help
Replies
2
Views
48K

Hot Threads

Recent Insights

Back
Top