Proper Handling of Volumetric Wares and the Determination of Density

NAME: Rosero, Hanna Mae R. SUBMITTED TO: Ms. Minerva R. Basilio DATE: July 11, 2011

ABSTRACT In getting the volumes of liquids and solving for densities, accuracy is very vital. Our

experiment showed proper handling of volumetric wares and the use of other apparatus. With proper handling or use of the apparatus, accurate measurements are achieved.

INTRODUCTION

To measuring the liquids, we often just use apparatuses that have calibrations. What we don’t know is that some apparatus are not good for measuring but only with containing liquids, like the beaker. Proper knowledge of what to use and what not to use is important. There are volumetric wares that measures volume accurately: Graduated Cylinder, Pipet, and the Buret. But knowing what to use isn’t good enough. Proper handlings of those wares are also important. The experiment will show how to properly use these wares.

METHODOLOGYA.THE GRADUATED CYLINDER

1. Obtain a 25 or 50 - mL graduated cylinder.2. Weigh a clean, dry 50 - mL beaker and using the triple beam balance. Record the mass.3. Use your wash bottle to add distilled water carefully to the graduated cylinder until, in your

judgement, it contains exactly 10.0 mL. Record the volume.4. Pour the water sample from the cylinder into the weighed beaker. 5. Weigh the beaker and contained water on the same balance used in step 2, and record the

mass.6. Without emptying the beaker, add a second carefully measured 10.0 mL sample of water

from your graduated cylinder. 7. Weigh the beaker and contained water of both samples on the same balance used before

and record the mass.

B.THE PIPET 1. Obtain a 10 mL pipet. Record the pipet volume.2. Weigh a clean, dry 100 mL beaker using the triple beam balance. Record the mass.3. Place about 50 mL of distilled water into a clean 100 ml beaker.4. Use a rubber aspirator and draw the distilled water from the 100 mL beaker into a pipet to

a level above the calibration mark.5. Quickly remove the aspirator and place your fore finger tightly over the top end of the

pipet to keep the water from flowing out.6. Control the flow of water out of the pipet by adjusting the pressure exerted by your finger.

Carefully allow the water meniscus to drop to the level of the calibration mark.( but not lower).

7. Touch the pipet tip to the side of the container of the distilled water to remove the attached drop.

8. Allow the pipet to drain into the weighted beaker. When the pipet stops draining, touch the tip to the side of the beaker to remove some of the water in the tip. Any water that

remains in the pipet after this procedure is not to be blown out. The pipet is designed to deliver the stated volume even though a small amount remains on the tip.

9. Weigh the beaker ans water on the same balance used in step 2. Record the combined mass.

C.THE BURET1. Obtain a 50 mL buret.2. Mount the buret on a ringstand by means of a buret clamp.3. Fill the buret nearly to the top with distilled water.4. Carefully open and close the stopcorck a few minutes to acquaint yourself with its

operaion. And also to remove any air bubbles from the tip of the buret.5. When you are ready to proceed, refill the buret and adjust the level of the meniscus to be

somewhere between 0.00 to 1.00 mL6. Read the water level to the nearest 0.01 mL and record this initial reading. 7. Weigh a dry beaker and record the mass.8. Carefully add 10 – 12 mL of water from buret into the beaker.9. Read the water level in the buret to the nearest 0.01 mL and record this final reading.10. Weigh the beaker and contained water on the same balance in step 7. Record the mass.11. Do not refill the buret or empty the first water sample from the beaker.12. Record the final buret reading from the first sample and the initial reading for the second

sample.13. Add another 10 – 12 mL of water from the buret to the beaker.14. Read the new water level in the buret to the nearest 0.01 mL and record it as final reading

for sample 215. Weigh the beaker and contained water on the same balance used before and record the

mass.

D.DENSITY OF SOLIDS1. Obtain a solid no.1 stopper2. Weigh a dry 50 mL beaker and record the mass.3. Place the rubber stopper in the weighted beaker, weigh them together, and record the

combined mass.4. Fill a 50 mL graduated cylinder approximately halfway with distilled water.5. Read the water level in the cylinder (remember to estimate to 0.1 mL) and record the value

in the blanked labeled “cylinder reading without stopper”6. Carefully put the stopper into the cylinder without splashing out any water. This is best

done by tilting the cylinder and letting the stopper slide down inside the wall.7. Tap the cylinder so the stopper sinks to the bottom. Swirl the water gently to remove any

clinging air bubbles from the stopper.8. Read the water level in the cylinder that now contains the stopper. Record the level.

RESULTS AND DISCUSSION

A. Graduated Cylinder

Volume of water in cylinder 10.0 ml

Mass of beaker + both samples 45.8 g

Mass of beaker + first sample 38.0 g

Mass of empty beaker 29.2 g

B. Pipet

Pipet Volume 10.0 ml

Mass of beaker + both samples 151.4 g

Mass of beaker + first sample 55.7 g

Mass of empty beaker 50.8 g

C. Buret

Sample 1 Sample 2

Final buret reading 39.5 ml 29.5 ml

Initial buret reading 49.5 ml 39.5 ml

Mass of beaker + both samples 68.8 g

Mass of beaker + first sample 58.4 g

Mass of empty beaker 50.8 g

A. Density of solid

Mass of beaker + stopper 33.9 g

Mass of empty beaker 29.2 g

Cylinder reading w/ stopper 55 ml

Cylinder reading w/o stopper 50 ml

Mass of the stopper 9.2 g

Volume of the stopper 5 ml

Density of the stopper 1.84 g/ml

CONCLUSION

These are the values we gathered from the experiment. In getting the volumes, we followed the value of the lower meniscus. In using the pipet, we found it hard to control the flow of water since it’s our first time using it. But then, we got the hang of it. One problem we encountered is the stopcock of the buret. We are no good with using it.

Using the Volumetric glassware can be very confusing but mastering them can be very rewarding because having accurate measurements are really important in experiments. Wrong measurements can result to a failed experiment. Thus, accuracy is very necessary.