front 1 Calibration | back 1 evaluating and adjusting the precision and accuracy of measurement equipment |
front 2 Buret | back 2 used in titration and is designed to measure the total volume of the solution delivered and permit drop-by-drop addition of the solution as the endpoint is approached |
front 3 How is a measurement made? | back 3 by reading the level before and after draining liquid from the
|
front 4 How do you read liquid level? | back 4 your eye at the same height as the top of the liquid, base from the bottom of the concave meniscus |
front 5 How do you read liquid level if the liquid is colorless or transparent? | back 5 at the top of the meniscus |
front 6 Parallax Error | back 6 error that occurs when your eye is not at the same height as the liquid |
front 7 How to calibrate buret? | back 7 measuring the mass of water delivered by the buret and using the density of water to convert mass into volume |
front 8 How to get rid of bubbles in tip of buret? | back 8 fill the buret with titrant and open the valve |
front 9 Step 1 of Calibration | back 9 fill the buret with distilled water and force any air bubbles out the tip. |
front 10 If drop clings on the wall? | back 10 clean with soap and water |
front 11 If drop persists on the wall? | back 11 soak with cleansing reagent |
front 12 Step 2 of Calibration | back 12 adjust the meniscus at 0.00 mL and touch the buret tip to a beaker to remove the suspended drop of water |
front 13 Step 3 of Calibration | back 13 allow the buret to stand while you weigh a dry, clean 100-mL beaker fitted with a clean rubber or cork stopper. While weighing, hold the beaker with a tissue paper. |
front 14 Why do we need to hold the beaker with a tissue paper? | back 14 to avoid fingerprint residue |
front 15 What if the level of liquid in the buret has changed? | back 15 tighten the stopcock and repeat procedure |
front 16 Step 4 of Calibration | back 16 Drain approximately 10 mL of water (at a rate of <20 mL/min) into the weighed flask. Allow about 30 seconds for the liquid on the wall to descend before you read the buret. Estimate all readings to the nearest 0.01 mL. Weigh the flask again to determine the mass of water delivered. |
front 17 Why do we have to cap the flask tightly? | back 17 To avoid evaporation |
front 18 Step 5 of Calibration | back 18 Without emptying the beaker or refilling the buret, again allow water to flow into the beaker until the reading is 20 mL and measure the mass of water delivered. Repeat this process at 10- mL intervals until the 50-mL mark is reached. Perform a second trial. |
front 19 Step 6 of Calibration | back 19 Use table 2 to convert the mass of water to the volume delivered to compute for the true volume |
front 20 Where should the correction agree on its approximate? | back 20 ±0.04mL |
front 21 Step 7 of Calibration | back 21 If the results do not agree, repeat the calibration process until
they do. Average the buret correction results of the two trials and
prepare a plot of the mean correction against the buret readings (at
each |
front 22 Step 8 of Calibration | back 22 After the final weighing, determine the temperature of the water. The initial and final temperatures should agree within about 10 C. |
front 23 Why should the initial and final temperatures agree within about 10 degree celcius? | back 23 To ensure consistency in results and minimize systematic errors as well as having the thermodynamic equilibrium |
front 24 True Volume Formula | back 24 Apparent mass of water * Density of Water |
front 25 Buret Correction Formula | back 25 True Volume - Buret Reading |