Calibrating a 50 ml buret lab report

USE OF VOLUMETRIC EQUIPMENT

PURPOSE

The purpose of this experiment is learning about the different types of glassware used in the laboratory and the calibration of the equipment for minimization of error and techniques for measuring volumes accurately.

PROCEDURE

The volumetric glassware that we are using for the experiment is a 50 mL buret, 25 mL volumetric pipet, one 100 mL graduated cylinder, one medicine dropper and a pipet bulb. All the glassware must be cleaned before use.

The experiment is divided into four parts with each of the glassware used in separate parts of the experiment. For all the parts, a 400 mL of DI water is set aside.

Part A (Using the Pipet)

1. All the air needs to be squeezed out of the bulb of the pipet. Taking a note of the calibration mark on the pipet, the pressure on the bulb is release so that the pipet starts filling up with water and we release the bulb only to an extent so that it reaches the calibration mark and does not shoot up to the bulb.

2. There could be a minimal adjustment to be made which can be done by removal of the bulb and quickly placing the finger on the top of the bulb and then adjusting of the fingers would help in releasing any extra water as we need to ensure the meniscus touches the top of the calibration mark.

3. The measured volume now must be moved to the receiving container without jerking or shaking and the tip of the pipet is placed against the side of the container to deliver the water to the container.

4. We will perform the experiment with three trials to get a consistent result, so we take 3 clean, dry 125 mL Erlenmeyer flasks and are named as 1,2,3 with a pencil.

5. Each of the flask is weighed on an analytical balance and the mass is recorded.

6. The flask 1 is then delivered with 25 mL of DI water using a 25 mL volumetric pipet from the solution of water kept aside for the experiment. The weight of the flask is recorded using the analytical balance.

7. The step 7 is repeated two more times for flask 2 and 3 and the mass that is delivered to each flask is calculated

8. The used flasks are rinsed with water and are dried with paper towels.

Part B (Using the Graduated Cylinder)

9. A clean dry graduated cylinder is taken for the part of the experiment and the weight is measured using the analytical balance and then filled up to the 100 mL mark with DI water. To ensure precision of the measurement, the final drops of the water are added using a dropper, so the meniscus is close to the 100 mL mark.

10. The weight of the graduated cylinder is measured again and noted in the lab notebook.

11. Empty the cylinder and the step 10 is performed again twice to obtain consistent value of mass and all the readings are recorded for further calculations

Part C (Using the Buret)

12. The setup of the buret on the support stand with buret clamps is very important to ensure the safety in the lab as this glassware may roll off the lab desk and fall on the ground and break. The position of the clamps is adjusted to ensure the buret is vertical to the eye. The buret should be setup on the support stand with buret clamps. The buret should be placed in the clamps and the position is to be checked to ensure it is vertical to the eye.

13. A 125 mL Erlenmeyer flask is placed below the buret and the buret is firstly made available for use by rinsing with a small quantity of the solution that we are using (DI water) (about 15-20 mL of the DI water is poured into a clean 50 mL beaker and then poured into the buret with funnel for rinsing)

14. When the buret is properly rinsed, it is filled with DI water to above 1mL mark by pouring water. Since this is a difference measurement, it is not necessary to fill the buret to 0.00 mL mark. The calculations of volume will happen with difference in initial and final readings.

15. We take three clean, dry 125 mL Erlenmeyer flasks are taken and identify them as 1,2,3 with a pencil and each of the flask is weighed on an analytical balance and the mass is recorded.

16. The initial volume of the buret is recorded checking the reading of the calibrated mark. The tared flasks are placed under the buret and about 35 mL of the DI water is transferred and the final volume is recorded.

17. Step 16 is repeated 2 more times by dispensing the DI water into the remaining two flasks aiming at 30-35 mL every time. The initial and the final buret volumes for each case are recorded.

18. The flask is weighed again on analytical balance and mass is recorded.

19. The mass and the volume measurements of each trial are used to calculate the density of water in each trial. The difference in the measured and the theoretical values will help us with calculation of the percentage difference.

Part D (The Volume of One Drop of Water)

20. A clean and empty 50 mL beaker is used for this part of the experiment. The beaker is weighed using the analytical balance.

21. We are adding 30 drops of the water from the DI water solution set aside to the beaker with the help of the medicine dropper drop by drop. The weight of the beaker is weighed again, and the difference is used for calculation of volume of the 30 drops of water added.

FUN FACT

There are multiple types of flasks. One of the most common flasks in a chemistry lab is an Erlenmeyer flask which we are using in this experiment also. This type of flask has a narrow neck and a flat bottom. It's good for swirling around liquids, storing them, and heating them.

SAFETY

There are few basic safety measures that needs to be taken care not only in this lab but all the labs that we perform in our life and in this course. Closed toe shoes must be work with apron or a lab coat and the safety glasses are to be sued always during the lab. We are not allowed to bring any kind of food or drinks inside the lab. Since, al the glassware is made of glass, they must be handled very carefully. All glassware must be rinsed and washed before use and after use. Prober support stands, and clamps are to be sued to prevent rolling off the instruments from the lab desk and breaking off.