Liyalle dudlellizallulllaealall INTERNATIONAL SAMI NOVERSTY MALS ireueion MA ea Cale BSCH 1323 ANALYTICAL CHEMISTRY | LAB 1 INTRODUCTION TO ANALYTICAL CHEMISTRY LECTURER'S NAME. DATE / DAY : 21/03/23, TUESDAY GROUP MEMBER MATRIC NUMBER NUR AINNAJWA BINTI SUID 2213280 NUR AINA NASUHA BINT! ZULKAFLI 2211960INTRODUCTION Objective: 1. Learn to match the most convenient device with the exact precision needed for measuring the task in a chemistry laboratory 2. Ability to read measuring devices correctly and handle the laboratory equipment properly. 3. To determine the mass of a sample using weighing instruments 4, To determine the magnitude of the errors in determining the volume of liquid dispensed from the instruments Finding the most accurate results in any laboratory depends on recording reliably measured data. Accuracy can be obtained with the closeness of data to the true value. However, the degree of accuracy and precision of a measuring system is related to the uncertainty in the measurements. Uncertainty in measured values refers to the numerical difference between a measured value and a true value. In addition, there are two important, though often neglected parts of an analysis which are error analysis and correct results reporting. Results should be reported along with some estimation of the error involved. In order to perform a scientifically valid error analysis, measurements at least three times are required. The analytical balance, pipette, and burette were the three tools utilised in this ‘experiment to conduct analytical measurements. An analytical balance is used to. determine the mass of solid and liquid with a readability of up to 0.001 g using the principle of magnetic force restoration. However, pipette and burette are designed only for volumetric analysis for liquid in different usage and precision. While a burette is used specifically to deliver a chemical solution with a known concentration to a flask, a pipette is used to measure the amount of analyte. Calibration of these two instruments may be done by measuring the weight of water delivered by particular glassware. Then with the density of water or the volume of 1 gram of water at a measured temperature, the correct volume is calculated.Apparatus: 50 mL burette Volumetric Pipette Thermometer 50 mL beaker Analytical balance Retort stand Bulb Weighing bottle PN OR aENs Material: 1. WaterPROCEDURE Experiment 1: Introduction to Analytical Measurements |. Introduction to the Analytical Balance In your notebook prepare a table using Table 1 as a template and do it in three copies. Next, the balance must be inspected first and you have to make use of the balance control. The bubble must be in the middle of the bullseye and the analytical balance must be clean. Always wear gloves first. The balance must be zero by pressing the tare button The mass of a clean, dry weighing bottle without a lid is determined within + 0.1 mg. The mass of the weighing bottle lid is determined separately within + 0.1mg The total mass of the weighing bottle plus the lid is determined within # 0.1 mg and the result is compared with the sum of the separate weights of the bottle and the lid to see how close the weights are. The weighing bottle without the lid is reweighted to see how reproducible the weight is. Then the gloves take off. The weighing bottle is rolled around your hands and reweighed and the results are recorded. Then compare the weight with the previous results. Wear the glove again and then the weighing bottle is wiped clean and dry, with a lint-free cloth or with laboratory tissue, The weighing bottle is held an inch from your mouth and breathes on it several times. Weigh it again and compare the results to earlier weights. The weighing bottle is placed in a drying oven for two to three minutes. The bottle is removed from the oven with tongs and immediately reweighs while it is still warm. Do not take the weighing bottle out. Follow the change in its apparent weight for 2 three minutes, the weight is recorded every 30 seconds The weighing bottle lid is weighed. The lid is removed from the balance and writes your initials with a pencil on the ground-glass surface then the lid is reweighed and the difference in the weight is recorded.Ul. Procedure Calibration of Volumetric Pipets The data is prepared in your lab notebook like Table 1. The tolerance of the pipette is stated. This experiment is replicated five times ‘SmL, 10mL, and 25 mL volumetric pipets from your TA are obtained. These should all be volumetric pipets labeled “TD” which is an abbreviation for "To Deliver" a certain amount of liquid (this type of pipette is called a Mohr pipette and it does not need to be blown out to empty the pipette). The tips had to be inspected. If you see a flaw, bring the pipette to your TA for evaluation. A chipped tip will affect the volume delivered, this will affect your grade in future labs. Clean your pipettes, using soap and water until they drain without leaving any droplets behind, other than the usual volume left in the tip The 50 mL beaker is a tare. 5,00 ml pipette deionized (Dl) water into the flask and the mass of water added to determine (remember to check for any bubbles that need to be removed, for the meniscus, and for the droplet of the water at the tip as the weight of every drop counts). The temperature of the water is measured with a thermometer (make sure that the thermometer does not touch the wall or the bottom of the container) The density of the water at the measured temperature is determined using Table 2 below. (use the table of the second-order polynomial to determine the density at the temperature of your sample). The correct volume that has been delivered by the pipet is determined by dividing the density of the liquid at the measured temperature into the weighted mass of the water. mo vont) = 8 TD Where V is the calculated volume from the density, m is the mass of the water, and d is the density of the liquid at the measured temperature. The calculated volume and the capacity of the pipette are compared. They should be the same.Table 2: The relationship between the temperature and density of water. Temp. (-C) | Density (g/mL) 10 0.997026 u 0.9996084 12 0.9995004 13 0.9993081 14 0.9992474 15 0.991026 16 0.998946 17 0.987779 18 0.998586 19 0.984082 20 0.9982071 21 0.9979955 22 0.977735 23 0.975415 24 0,9972995 25 0.9970479 26 0.9967867 27 0.9965162 28 0.9962365 29 0.9959478 30 0.995602Il Procedure Calibration of the Burette © The burette is obtained and cleaned. A clamp is used to set it up and the room temperature equilibrated water is filled to above the mark. Make sure that no air bubbles are trapped in the tip or the stopcock. About 1 minute is allowed for drainage. @ The liquid level is lower to bring the bottom of the meniscus to the 0.00 mL mark. © The tip of the burette is touched to the wall of a beaker to remove any adhering drop. * Recheck the volume after 10 minutes. If the stopcock is tight, there should be no changes in the reading. © While waiting, create a table in your lab notebook to record the reading of the burette and mass of water dispensed as suggested in Table 4. A clean 50 mL is a tare, ‘Once the tightness of the stopcock has been established, 10 mL of the liquid is transferred into the weighted beaker. The tip of the burette is touched to the wall of the beaker as the weight of every drop counts. © The initial reading on the burette is recorded. Generally estimate between graduations typically, people estimate 1/5 of the spacing between graduations. (If the spacing between graduations is 1 mL, estimate the volume to 0.2 mL. If the spacing is 0.1 mL, estimate the volume to 0.02 mL, etc.) The mass of the transferred water is recorded. The volume of water left in the burette is recorded that is apparently delivered and refilled * Check Table 2 to determine the density of the transferred water according to the temperature of the liquid. Calculate the true volume of the transferred water by dividing the density of the liquid at the measured temperature by the mass of the water. © The apparent volume (burette) from the true volume (mass) is subtracted. The difference is the correction that should be applied to the apparent volume to give the correct value. © The calibration is repeated starting again from the zero mark, this time 20 mL is delivered to the receiver. * The burette is tested at 10 mL intervals over its entire volume: 10, 20, 30, 40, and 50 mL. Remember, all must start from the zero mark, © Prepare a plot of the correction to be applied as a function of volume delivered (apparent volume). * The correction associated with any interval can be determined from this plot. Notice that this correction may be either positive or negative and is an additive correction term applied to the apparent volume.Procedure Micropipette pa xsi Ay Tp ejector a iia istay “in elector coliar —— What are the different pipetting techniques used? The frequently used pipetting techniques include forward pipetting and reverse pipetting. Before we understand these techniques in detail, the general instructions for pipetting listed below would be noteworthy. © Press and release the plunger slowly, always, particularly when working with high-viscosity reagents/solutions. Make sure that the plunger does not snap. Make sure the tip is firmly attached to the tip cone. Before starting your experiment, fll and empty the tip 2-3 times with the reagent or solution that you will be pipetting. © Hold the micropipette in an upright position while aspirating. The Grippy (ergonomic grip cover) must rest on your index finger. * Make sure that the tips, the micropipette, and the reagent/solution are at the same temperature. Be ready with the pipet tip waste disposal container. © Aspirate and dispense the liquid slowly and not abruptly to avoid bubble formation.|. Procedure drawing Micropipette © Set the needed volume by adjusting the volume adjustment knob. © Press the plunger until it reaches the First Stop. When you feel resistance in the plunger, you have positioned it to draw the set amount, * Immerse the disposable tip of the pipette into liquid. Hold the pipette at a 90° angle so it forms an L-shape with the surface of the liquid. If possible, hold the tip about a quarter inch (.64 cm) from the bottom of the liquid’s container [1] However, do not submerge the shaft of the pipette in the liquid. * Be careful not to press the tip of your pipette against the bottom of the fluid’s container. This could also cause damage to the pipette tip. © Draw fluid into the pipette: When the tip is immersed, use the plunger button to allow the plunger to return to its starting position (fully extended). Do this slowly so the plunger does not snap out, Make sure that the tip of the pipette remains in the solution whilst releasing the plunger to ensure that no air bubbles make it into the tip, * Wait a few seconds after the plunger returns to its original position before moving the pipette, This will ensure the full amount of liquid is taken. Remove the tip of your pipette from the liquid. ILProcedure dispensing Micropipette * Position the pipette over the receiving container. Position the pipette on an angle, 80 its tip touches the side wall of the receiving container and forms a 45° angle (halfway between up and down and flat). You may drag the tip upward whilst, dispensing® Dispense the liquid into the receiving container. If there is already fluid in the receiving container, hold the pipette so its tip is just above its surface or slightly above the bottom of the container. Gently push the plunger to the First Stop to release the liquid. While the pipette is still in the container, wait a few seconds with the plunger engaged to the First Stop, Now you are ready to press the plunger to the Second Stop to remove any liquid still in the tip. Should there be a droplet hanging at the tip, touch the tip to the inside wall of the receiving container. * Remove the pipette from the receiving container. Continue to hold the plunger down after reaching the Second Stop. Take the pipette out of the container and release the plunger slowly until it has returned to its original (fully extended) position. © Dispose of the tip safely and return your pipette to a safe storage location (make sure that they are stored vertically). The tip can be removed easily with the tip ejector button (caution: do not remove the tip with your hands). However, this will cause the tip to spring free of the pipette. Make sure the tip is pointed at a suitable receptacle before pressing the ejector button, then put your pipette away. lILProcedure Forward Pipetting Technique for aqueous solutions such as dilute reagents, buffers, diluted acids, or alkalis.Method 1: Forward pipetting Sed f © To aspirate the liquid in the tip, press the plunger to the first stop. Immerse the pipette tip vertically in the liquid, © Slowly release the plunger while the tip is immersed, The liquid will be aspirated into the pipette tip. © To dispense the liquid, place the tip on the inner wall of the receiving vessel at a steep angle. Slowly press the plunger to the first stop to dispense the liquid. To empty the tip completely, press the plunger to the second stop. Drag the tip on the inner wall while taking the tip out of the vessel Release the plunger slowly until itis at its initial position. IV. Procedure Reverse pipetting technique. The reverse technique is suitable for dispensing reagents/solutions that have high viscosity or a tendency to foam/create bubbles easily. Itis also recommended for dispensing very small volumes.Note: Method 2: Reverse pipetting To aspirate the liquid in the tip, press the plunger to the second stop and immerse the pipette tip vertically in the liquid. Slowly release the plunger while the tip is immersed. The liquid will be aspirated into the pipette tip. To dispense the liquid, place the tip on the inner wall of the tube at a steep angle. Slowly press the plunger to the first stop. Drag the tip on the inner wall while taking the tip out of the vessel. Release the plunger slowly to its original state. Residual liquid remains in the tip. This does not belong to the dispensing volumeDATA AND OBSERVATION Analytical balances were used to measure the results. Throughout the process, each step was repeated thrice to ensure consistency and reliability. In the following steps, mass, mean mass, standard deviation, and standard relative deviation were calculated. The average mass of the objects can be calculated by dividing the total mass of the objects by the number of samples in order to get the mean mass. In order to calculate the standard deviation, the differences between the measurements and the mean mass were added up and divided by the number of measurements. The relative standard deviation can be obtained by dividing the standard deviation by the mean mass. |. __ Introduction to the Analytical Balance Step Object Mass 0.1 | Mean Standard Relative number mg Mass deviation —_| standard (3 values) deviation 3 Clean, dry 46.8320 46.8343 3.955 x 10*-3 | 8.446 x 10*-3 bottle 46.8389 46.8321 4 Lid 1.8296 1.8296 [7.071 x 10%5 | 3.865x 10%3 1.8297 1.8296 5 Bottle and lid 46.6617 46.6618 1.0 x 10*-4 2.143 x 10%-4 46.6619 46.6618 é Bottle without | 44.8337 [44.8338 | 1.225x 10%4 | 2.732 x 10%4 lid 44.8339 44.8337 7 Bottle with 44.8342 |44.8340 |6.671x10%-4 | 1.484 x 10*-3 finger 44,834644,8333 8 Bottle after 44.4662 44.4663 1.732 x 10%-4 | 3.895 x 104-4 breathing on it 44.4662 44,4665 9 Hot bottle 46.6623 | Not Not Not applicable applicable | applicable 30 sec 46.6623 60 sec 46.6622 90 sec 46.6622 120 sec 46.6623 150 sec 46.6623 180 sec 46.6622 10 Lid 1.8300 1.830 2.580 x 10%4 | 0.0139 1.8297 1.8302 id with pencil | 1.8296 18298 |2.121x 10-4 | 0.0116 initials 1.8300 1.8299 Table 1 : Result measured using the analytical balanceCalibration of Volumetric pipettes mean mass/density Temperature of water: 23°C Mass of beaker: 34.2738 Volume Mass Mean | Standard | Relative (mL) 401mg | mass | deviation | standard deviation Corrected volume (mL) 5S mL 3.7671 3.6666 0.3747 0.1022 3.0039 3.7864 3.8944 3.8814 3.6756 10 mL 8.7837 | 8.6938 0.08963 0.1031 8.7134 8.6361 8.5704 8.7653 8.7152 25 mL 24.1426 | 23.5816 0.3445 0.0146 23.5156 23.5730 23.4751 23.2019 23.6397 Table 2: Results measured using volumetric pipettelll Calibration of the Burette ‘Temperature of water: 23°C Mass of beaker: 29.7790 g Volume of liquid Mass of True value Corrected (mL) transferred (mL) burette water (g) (mt) 10 9.9310 9.9532 0.0468 20 20.0710 20.1158 -0.1158 30 29.9600 30.0269 -0.0269 40 39. 9100 39.999 0.0009 50 49.9100 50.0214 -0.0214 Table 3: Results measured using buretteDISCUSSION a) Analytical balance The standard weighing bottle is prepared before weighing, the whole bottle including its lid was cleaned and wiped dry with laboratory tissue to ensure that it was not contaminated with chemicals or dust. The presence of chemicals or dust on the bottle and lid could affect the mass of the bottle from the beginning, thus altering the whole weighing process and the actual mass of the bottle. Hence, our data would have lower accuracy than expected, The mean mass is important as it simplifies the data, while the standard deviation describes how dispersed the data is from the mean. The relative standard deviation expresses the precision and reproducibility of the data Firstly, the bottle and its lid were weighed separately then it was weighed with its lid capped on. The total mean mass of the separate weights was compared to the mean mass of the whole bottle, lid included, and the results recorded were not far off from each other with the values of 46.8343 g and 46.6618 g respectively, These results differed by only 40.1725 g from each other, However, the total standard deviation for the separate weights was seen to be higher than the standard deviation of the bottle with its lid. The lower standard deviation indicates that the data is more consistent and clustered around the mean as compared to the data of the separate weights. Furthermore, the total relative standard deviation of the separate weights was also recorded to be higher than that of the relative standard deviation of the bottle with its lid. Thus, justifying that the data in which the bottle was weighed with its lid is more reliable than when the bottle and its lid were weighed separately. Ensuing, the weighing bottle without its lid was handled without gloves to observe how the dust and sweat from fingers and hands could affect the mass of the bottle as mentioned in the first paragraph. The hypothesis in our data would have lower accuracy than expected was proved to be true as the relative standard deviation of the weighing bottle when handled with gloves is lower than when it was handled without with a difference of #4.703x 10.6. The presence of dust and sweat accumulated from fingers contaminated the bottle. Then, based on the result, we get the different values for the dry bottle and the bottle after breathing on the bottle heat in the oven which is because the changes in carbon dioxide which the person breathing on it has a different level of temperature from the mouth and the temperature in the oven. If it was a hot temperature, the bottle would weigh less whereas if it was a low temperature, the bottle would have greater weight.b) Pipette Volumetric pipette for SmL. 10mL and 25mL were calibrated to reduce the determinate error and increase the accuracy of the data. ‘Volume (mL) Tolerance (mL) 05 I + 0,006 1 + 0.006 2 + 0,006 3 £0.01 4 £0.01 3 £0.01 10 + 0.02 15 + 0.03, 20 + 0.03, 25 «0.03 50. £0.05 100 + 0.08 Table 4.1 shows the value of tolerance (mL) for each volume (mL) in the pipette The true volume of water for the pipette is 5.0mL delivered and has a tolerance of about £0.1 from its corrected volume which was 3.6756 mL. Based on Table 4.1 row 6 showed that the 5,0 mL pipette does deliver the correct volume in the experiment as stated in Table 4.1 which was 0.1. The 15.0mL pipette delivered 9.9708 ml and has 40.3 tolerance from its corrected volume which was 10.0 mL. The tolerance for 10.0mL was slightly higher than the tolerance table which was only £0.2 for the 15mL pipette. Next, the 25.0 mL pipette has a bigger tolerance than other pipettes in Table 4.1 which was +0.3. However, the number of tolerance measured in this experiment was obviously different, which was 40.7 tolerance rather than £0.3 in the table shown. Thus, the tolerance of the table showed that a range between is acceptable in the experiment. However, the 5.0 mL and 25.0 mL are slightly different from Table 4.1, so the data may have less precision than expected. -relative sd &sd Standard deviation of data showed the spreads of the data and the relation to the mean lower relative standard deviation showed higher precision in the data whereas higher dispersion indicates lower accuracy.©) Burette ‘A50 mi calibrated burette was used in this part of the experiment. It was fully filled with water without the presence of air bubbles. As the burette ensured there were no air bubbles, 10 mL of volume was blown out into the 50 mL beaker. Then, the beaker is weighed on the analytical balance. The 9.9310g of transferred water was measured and discarded to proceed to the next step. The -0.10 mL true value of the liquid was calculated by dividing the mass transferred to water by the density of the liquid which is 9.9532g at 23°C. The same method is being used for 20 mL, 30 mL, 40 ml and 50 mi and before we continue the experiment, the burette is filled up with water. The tolerance of 50 mL burette which is allowed by the National Institute of Standards and Technology for Class A is #0.05 mL. The corrected volume of 10mL, 20 mL, 30 mL, 40 ml and 50 ml are 0.04mL, -0.12mL, +0.03mL, 0.0009mL and -0.02mL. Corrected burette (mL) vs. True value 0.05 0.00 + + 0.08 0.10 10 20 20 40 50 True valeCONCLUSION In conclusion, an analytical balance is a better option for your laboratory if you need great accuracy. The precision of an analytical balance is between 0.0001 and 0.00001g, If extreme accuracy is not important a top-loading balance will work just fine in measuring the accuracy of 0.001g.As a result, it can be concluded from the experiment that there are five typical sources of mistakes that have a significant impact on the sample's weight. Static electricity, which is an imbalance of positive and negative charges of the sample or environment, would attribute changes in the weight of the sample. These errors were caused by buoyancy, which was the force exerted in the clean crucible, changes in moisture content, which adds up the weight on the sample, changes in carbon dioxide, which came from the person who breathed on the sample, the temperature of the crucible and environment, and buoyancy. The laboratory staff or the individual weighing a sample in the balance can also decide that many errors that might be introduced into the weighing operation can be eliminated by carefully referring to the many procedures on how to operate the analytical balance, However, it is important for each analytical balance to be serviced and calibrated regularly by specially trained internal or laboratory personnel REFERENCES 1. LibreTexts CHEMISTRY (Feb 3, 2023) Calibration of Volumetric Glassware 4: Calibration of Volumetric Glassware (Experiment) - Chemistry LibreTexts, 2. LAB SUPPLY NETWORK (August 24, 2017) What is the difference between an Analytical Balance and a Precision Balance? Difference between an Analytical Balance and a Precision Balance | Lab Supply laboratory-supply.net} 3. LibreTexts CHEMISTRY (Feb 5, 2023) Use of Volumetric Pipet Use of a Volumetric Pipet - Chemistry LibreTexts