Complete Guide of Burette Reading

 

Burette is a graduated glass tube with a stopcock (valve) to control the flow of the liquid. The tool finds its use in the titration process for quantitative analysis of various chemical tests. The controlled amount of solution of known concentration (titrant) is dispensed to find the concentration of an unknown solution (analyte). The titrant is added until the endpoint is reached, which is marked by a color change or precipitate formation. A buffer or pH solution indicates the end of the titration process. The titration process is one of the most frequently used quantitative analyses that help researchers develop or analyze chemical compounds. Also, it is used in various industries to analyze chemical compounds such as environmental studies, winemaking, pharmacology, wastewater analysis, and nutritional implications of food products. Titration looks like a simple procedure, but if not performed carefully, the results obtained are incorrect. There are various steps involved in the titration process and each must be carried out with vigilance to obtain the correct results. Here is a complete guide to using and burette reading. Filling the burette The burette helps measure the correct amount of liquid allowed to pour into the conical flask. It makes the task of delivering a measured volume of liquid of desired quantity. However, to avoid any mistakes and for proper burette reading, the burette must be clamped vertically and ensure the valve is closed. Fill the burette with the titrant solution using a funnel by lifting the funnel a bit to let the solution flow freely. Conditioning the burette Conditioning the burette is essential before the experiment to ensure that the titrant remains unchanged by a tiny drop of water. To condition the burette, rinse it well with titrant solution ensuring that the entire surface gets perfectly coated. Drain the solution and repeat the process a couple of times. Flush air bubbles Next, you need to flush any air bubbles within the burette. If there are air bubbles in the burette, they add volume to your initial reading leading to errors. Fill the burette with titrant and place a waste beaker beneath it. Briefly open the valve as you pour the solution as it flushes out air bubbles. Close the valve and fill the burette to the 0 mark. Now note the initial reading. Performing the titration Ensure the top of the burette is below eye level. Lower the burette stand or stand on a stool to reach it. Place your left hand around the valve of the burette while with the right-hand swirl the conical flask when titrant is added. When starting the process, allow the titrant to flow in a continuous stream. When the indicator color change becomes a little persistent, switch to adding single drops. When desired indicator color persists for 10 seconds after mixing, the experiment reaches the endpoint. Now note the final reading.

How to read a burette? The purpose of burette reading is to know how much solution is dispensed. The measurement scale on a burette is at intervals of 0.10 and the burette reading is read to an accuracy of 0.05 ml. When reading the burette, make sure your eye is at the level of the meniscus to avoid the error. The meniscus is concave or U-shaped for most solutions. Read the center of the meniscus or the bottom of the U-shape to record the correct reading. Record the initial and final reading. The difference between the two is the titer and determines how much titrant is added into the analyte. Also, ensure to record the reading to the nearest 0.05 ml. Burette reading is an essential step, and if not recorded correctly, the entire experiment fails. Microlit USA offers a digital burette that is easy to use, minimizes the risks of multiple errors, and displays the reading up to the second decimal on the TFT screen.