The type of balance used will depend on the number of significant figures desired in the final result. For example, if you require the result be displayed to the hundredths place, a two place balance would suffice. On the other hand, if your results are reported to the fourth decimal, a four place balance should be used. A calibrated and stable analytical balance is recommended for the most accurate weight. This one sounds obvious, but is a necessary reminder.
If you are working with an electrode for your titration, you should know that the success or failure of the measurement depends on the condition of the probe. A pH electrode should be calibrated each day at least once it is used to get the most accurate reading. A two-point method is typically sufficient, as long as the appropriate buffers are used. What do we mean by appropriate? Buffers should be chosen based on your routine measurement range.
For example, if your titrations typically take place in the pH range, you should select pH buffers 4 and 7. Using fresh and clean buffers is also important for a successful calibration. The offset and slope may change as well and this, again, will dictate how frequently the calibration should be done. The following limits are widely used, within which an electrode is still considered to be trustworthy:. Zero point pH 6.
The pipette allows the same volume of acid to be added each time, helping to make the results repeatable. Describe two steps needed to obtain accurate results.
Take the readings from the bottom of the meniscus. Near to the end-point, rinse the inside of the flask with distilled water and add the acid drop by drop. Explain the importance of a suitable indicator in obtaining accurate results. The indicator must change colour sharply when the solution in the flask is neutralised. This means the volume of acid measured is very close to the true value. The white tile makes it easier to see the colour change.
Misjudging the colour change could result in a random error. It is important in this practical activity to use appropriate apparatus and methods. This includes the safe use and careful handling of substances. Evaluate the hazards and the precautions needed to reduce the risk of harm. For example:. Practical activity - carrying out a titration Titration There are a number of ways that you could carry out a titration in Chemistry.
Skip to main content. Aqueous Reactions. Search for:. Acid-Base Titrations. Learning Objective Compute the concentration of an unknown acid or base given its volume and the volume and concentration of the standardized titrant.
Conical flasks are better than beakers for this procedure because they can be easily swirled without risk of the contents spilling. Burettes are tall, thin, graduated glass tubes, with a tap at the bottom that can be opened and closed to allow the solution inside to flow out. As with the pipette, the burette should be rinsed with distilled water followed by the solution it is to be filled with to avoid contamination issues.
The burette should be filled up to above the zero line, and then lowered down to it by opening the tap. The meniscus, the bottom of the water level in the burette, should be level with the zero mark.
Filling the burette this way is also useful because it means the space under the tap is also filled with liquid. This is important, as the burette is calibrated to include this volume. First, an indicator is commonly added to the conical flask. For acid-alkali titrations, this is a chemical that undergoes a colour change at certain acidities. Two commonly used examples are phenolphthalein and methyl orange.
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