Volume measurement beakers

Whether the volume measurements are for preparing solutions to be used in such a procedure, for transferring an appropriate volume of solution or solvent for such an analysis, etc., they need not be accurate since the outcome will be either only qualitative or not necessarily accurate. Such volumes should, however, be measured with other marked glassware, such as graduated cylinders or marked beakers and flasks. 

Other common laboratory containers such as beakers, round bottom flasks, and Erlenmeyer flasks often have a limited graduated volume designated on their sides. These markings provide an approximate volume and cannot be used for quantitative work. The required accuracy of these containers is only 5% of volume. When there are no calibration lines on a flask, it still is possible to obtain an approximate volume measurement based on the stated volume In general, the stated volume will approximately fill any given nonvolumetric container to the junction of the neck and container (see Fig. 2.13). Thus, if you need about 500-mL of water, it is safe to fill a 500-mL flask up to the neck and you will have approximately the needed volume. 

Empty the beaker and dry it as well as possible with a paper towel. Place 4 mL of water in the beaker again, but this time measure this volume by adding the water from a 50-mL buret. Again measure the mass of the beaker on the three balances and subtract the mass of the empty beaker to obtain the mass of the water on each balance. Then pour the water into the graduated cylinder and record the volume reading. Be sure to record the volume measurement and all mass measurements in your Data section and clearly label all entries. Again you will have three sets of data for the mass measurements, one for each balance. 

To measure density, the weight of a known volume of the liquid is measured and this weight is then divided by the volume to obtain density. For the volume measurement, you will use either a 10-mL buret or a 10-mL graduated cylinder. Make sure the buret or cylinder to be used is as dry as possible or rinsed in the manner described at the beginning of this SOP. (A buret is a graduated cylinder with a stopcock valve at the bottom.) Then, weigh a small (dry) beaker on the balance provided. Record this weight in your notebook. 

Volume measuring means the exact determination of a defined volume of a liquid (or of a powder mixture in the case of preparing capsules). Devices for measuring of volumes for pharmacy preparations include graduated pipettes (traditional or automatic), syringes and graduated cylinders. Beakers, Erlenmeyer flasks and medicine bottles are not fit for volume measurement, even if they are... 

The density determination may be carried out at the temperature of the laboratory. The liquid should stand for at least one hour and a thermometer placed either in the liquid (if practicable) or in its immediate vicinity. It is usually better to conduct the measurement at a temperature of 20° or 25° throughout this volume a standard temperature of 20° will be adopted. To determine the density of a liquid at 20°, a clean, corked test-tube containing about 5 ml. of toe liquid is immersed for about three-quarters of its length in a water thermostat at 20° for about 2 hours. An empty test-tube and a shallow beaker (e.g., a Baco beaker) are also supported in the thermostat so that only the rims protrude above the surface of the water the pycnometer is supported by its capillary arms on the rim of the test-tube, and the small crucible is placed in the beaker, which is covered with a clock glass. When the liquid has acquired the temperature of the thermostat, the small crucible is removed, charged with the liquid, the pycnometer rapidly filled and adjusted to the mark. With practice, the whole operation can be completed in about half a minute. The error introduced if the temperature of the laboratory differs by as much as 10° from that of the thermostat does not exceed 1 mg. if the temperature of the laboratory is adjusted so that it does not differ by more than 1-2° from 20°, the error is negligible. The weight of the empty pycnometer and also filled with distilled (preferably conductivity) water at 20° should also be determined. The density of the liquid can then be computed. 

Analytical chemists use a variety of glassware to measure volume, several examples of which are shown in Figure 2.4. The type of glassware used depends on how exact the volume needs to be. Beakers, dropping pipets, and graduated cylinders are used to measure volumes approximately, typically with errors of several percent. 

Calculate the molar concentration of NaCl, to the correct number of significant figures, if 1.917 g of NaCl is placed in a beaker and dissolved in 50 mF of water measured with a graduated cylinder. This solution is quantitatively transferred to a 250-mF volumetric flask and diluted to volume. Calculate the concentration of this second solution to the correct number of significant figures. 

The concentration of Ca + in a sample of sea water is determined using a Ca ion-selective electrode and a one-point standard addition. A 10.00-mL sample is transferred to a 100-mL volumetric flask and diluted to volume. A 50.00-mL aliquot of sample is placed in a beaker with the Ca ion-selective electrode and a reference electrode, and the potential is measured as -0.05290 V. A 1.00-mL aliquot of a 5.00 X 10 M standard solution of Ca + is added, and a potential of -0.04417 V is measured. What is the concentration of Ca + in the sample of sea water ... 

In the combustion reaction as carried out in the calorimeter of Figure 7-2, the volume of the system is kept constant and pressure may change because the reaction chamber is sealed. In the laboratory experiments you have conducted, you kept the pressure constant by leaving the system open to the surroundings. In such an experiment, the volume may change. There is a small difference between these two types of measurements. The difference arises from the energy used when a system expands against the pressure of the atmosphere. In a constant volume calorimeter, there is no such expansion hence, this contribution to the reaction heat is not present. Experiments show that this difference is usually small. However, the symbol AH represents the heat effect that accompanies a chemical reaction carried out at constant pressure—the condition we usually have when the reaction occurs in an open beaker. 

Pipette 25 mL of solution B into a 100 mL beaker mounted on a magnetic stirrer and add an equal volume of TISAB from a pipette. Stir the solution to ensure thorough mixing, stop the stirrer, insert the fluoride ion-calomel electrode system and measure the e.m.f. The electrode rapidly comes to equilibrium, and a stable e.m.f. reading is obtained immediately. Wash down the electrodes and then insert into a second beaker containing a solution prepared from 25 mL each of standard solution C and TISAB read the e.m.f. Carry out further determinations using the standards D and E. 

Prepare 250 mL of 0.02 M potassium dichromate solution and an equal volume of ca 0.1 M ammonium iron(II) sulphate solution the latter must contain sufficient dilute sulphuric acid to produce a clear solution, and the exact weight of ammonium iron(II) sulphate employed should be noted. Place 25 mL of the ammonium iron(II) sulphate solution in the beaker, add 25 mL of ca 2.5M sulphuric acid and 50 mL of water. Charge the burette with the 0.02 M potassium dichromate solution, and add a capillary extension tube. Use a bright platinum electrode as indicator electrode and an S.C.E. reference electrode. Set the stirrer in motion. Proceed with the titration as directed in Experiment 1. After each addition of the dichromate solution measure the e.m.f. of the cell. Determine the end point (1) from the potential-volume curve and (2) by the derivative method. Calculate the molarity of the ammonium iron(II) sulphate solution, and compare this with the value calculated from the actual weight of solid employed in preparing the solution. 

The chromium in the substance is converted into chromate or dichromate by any of the usual methods. A platinum indicator electrode and a saturated calomel electrode are used. Place a known volume of the dichromate solution in the titration beaker, add 10 mL of 10 per cent sulphuric acid or hydrochloric acid per 100 mL of the final volume of the solution and also 2.5 mL of 10 per cent phosphorus) V) acid. Insert the electrodes, stir, and after adding 1 mL of a standard ammonium iron)II) sulphate solution, the e.m.f. is measured. Continue to add the iron solution, reading the e.m.f. after each addition, then plot the titration curve and determine the end point. 

Record the volume of the cold water in the second beaker in Data Table 1. Place the beaker in a pan containing ice. Surround the breaker with additional ice. Use the thermometer to measure the temperature of the water. Record the temperature in Data Table 1. 

Using a clean 50-mL graduated cylinder, measure 25 mL of a solution of adipoyl chloride in cyclohexane and pour it into a 150-mL beaker. Record the volume used in Data Table 2. 

Procedure. A hexane solution of Compound 118 is diluted or concentrated so as to bring the 118 content within a range of 15 to 150 micrograms per ml. In cases where the hexane solution requires concentration, the evaporation is carried out in a beaker on a steam bath with a gentle stream of air passing over the surface. The concentrated or diluted solution of 118 is washed with hexane into a volumetric flask and made up to volume with the hexane washings. One milliliter of the adjusted Compound 118 solution is precisely measured into a spectrophotometer cell, 2 drops of phenyl azide are added, and the dihydrotriazole is quantitatively formed and then treated with diazotized dinitroaniline to produce the red color as in the preparation of the standard curve. A blank, starting with 1.0 ml. of hexane and 2 drops of azide, is run at the same time. 

To determine whether any loss of Compound 118 occurs on evaporation, a stock solution of Compound 118 in hexane was made up, and aliquots containing 20 to 250 micrograms of Compound 118 were measured into tail-form beakers and diluted to 250 ml. with hexane. The solutions were evaporated to 10 ml. on a steam bath with a jet of air passing gently over the liquid surface. Following the same procedure, solutions of Compound 118 of varying concentrations were reduced to convenient final volumes. After concentration, in the manner described, the Compound 118 content of the final concentrates was determined. 

Transfer that liquid to a beaker, cylinder or some large container. Find a multiple factor by dividing the volume actually measured with the volume... 

For the variation, the vapor pressure of water at the recorded temperature is found in a table. The pressure of the gas (I ) is the difference between the value in the table and measurement 1. The volume of water in the beaker is the volume of the gas (Vi). 

Use a graduated cylinder to measure 100 mL of distilled water. Very slowly, add the water to the beaker. Stop frequently to observe what happens. Keep track of how much water you add, and stop when no more water can be absorbed. (You may need to add less or more than 100 mL.) Record the volume of water at which the powder becomes saturated and will no longer absorb water. 

X 10 mol/L FelNOsls, and 0.200 mol/L Fe(N03)3. Pour about 30 mL of each stock solution into its labelled beaker. Be sure to distinguish between the different concentrations of the iron(III) nitrate solutions. Make sure that you choose the correct solution when needed in the investigation. Measure the volume of each solution as carefully as possible to ensure the accuracy of your results. 

Touch the tip of the pipette to the side of the beaker to remove any clinging drop. See Figure F.3. The measured volume inside the pipette is now ready to be transferred to an Erlenmeyer flask or a volumetric flask. 

There are three kinds of pipettes (A) TD (to deliver) pipettes, which deliver the final volume before the tip (no rings marked on the top of the pipette) (B) TD pipettes, which deliver the final volume to the tip and are designed to be blown out (marked with two double rings at the top of the pipette) (C) TC (to contain) pipettes, which deliver the final volume by touching the tip of the pipette to the side of the beaker or flask and leaving drop of solution in the pipette. TC pipettes are rare as opposed to TD pipettes. Volume is measured at the bottom of the meniscus. 

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