Preparing the solution

To prepare the solution we place 4.0 g of NaOH, weighed to the nearest tenth of a gram, in a bottle or beaker and add approximately 500 mL of water. 

To prepare the solution we measure out exactly 0.1500 g of Cu into a small beaker. To dissolve the Cu we add a small portion of concentrated HNO3 and gently heat until it completely dissolves. The resulting solution is poured into a 1-L volumetric flask. The beaker is rinsed repeatedly with small portions of water, which are added to the volumetric flask. This process, which is called a quantitative transfer, ensures that the Cu is completely transferred to the volumetric flask. Finally, additional water is added to the volumetric flask s calibration mark. 

To prepare the solution we use a graduated cylinder to transfer 80 mb of glacial acetic acid to a container that holds approximately 2 b, and we then add sufficient water to bring the solution to the desired volume. 

The time needed to complete an analysis for a single sample is often fairly similar from method to method. This is somewhat misleading, however, because much of this time is spent preparing the solutions and equipment needed for the analysis. Once the solutions and equipment are in place, the number of samples that can be analyzed per hour differs substantially from method to method. This is a significant factor in selecting a method for laboratories that handle a high volume of samples. 

Prepare the solutions and measure the pH at one temperature of the kinetic study. Of course, the pH meter and electrodes must be properly calibrated against standard buffers, all solutions being thermostated at the single temperature of measurement. Carry out the rate constant determinations at three or more tempertures do not measure the pH or change the solution composition at the additional temperatures. Determine from an Arrhenius plot of log against l/T. Then calculate Eqh using Eq. (6-37) or (6-39) and the appropriate values of AH and AH as discussed above. 

Prepare the solutions, thermostat them at the temperatures to be used in the rate study, and then adjust them all to the same pH value by the addition of small volumes of concentrated strong acid or base. The pH meter must be correctly calibrated at each temperature. Now carry out the kinetic study and calculate Eobs. Because this procedure has set d In (H )/d(l/T) = 0 experimentally, use Eq. (6-36) in the form = Eqh +... 

Prepare the solutions, thermostat them at the rate study temperatures, and measure the pH at each temperature, taking the correct precautions concerning calibration of the pH meter. Now convert each pH to (OH ), using (OH ) = A, /(H ), where... 

The purpose of the decomposition of raw materials is to convert tantalum and niobium compounds into a soluble form and prepare the solution for use in subsequent procedures. Fig. 116 presents the process flow chart. The most typical and frequently used raw materials are columbite-tantalite concentrates with the general formula (Fe, Mn)(Nb, Ta Cfo. 

The bottle should be clean and dry a little of the stock solution is introduced, the bottle well rinsed with this solution, drained, the remainder of the solution poured in, and the bottle immediately stoppered. If the bottle is not dry, but has recently been thoroughly rinsed with distilled water, it may be rinsed successively with three small portions of the solution and drained well after each rinsing this procedure is, however, less satisfactory than that employing a clean and dry vessel. Immediately after the solution has been transferred to the stock bottle, it should be labelled with (1) the name of the solution (2) its concentration (3) the data of preparation and (4) the initials of the person who prepared the solution, together with any other relevant data. Unless the bottle is completely filled, internal evaporation and condensation will cause drops of water to form on the upper part of the inside of the vessel. For this reason, the bottle must be thoroughly shaken before removing the stopper. 

Method B. Prepare the solution and transfer 25 mL of it to a 250 mL conical flask as detailed under Method A. Add two to three drops of diphenylcarbazide indicator and titrate with standard 0.1M silver nitrate solution until a permanent violet colour is just produced. 

Prepare the solution with recently boiled distilled water. 

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. 

A small lead jar is excellent for preparing the solution. By the use of a lead stirrer of the usual shape, mechanical stirring may be used. The stirrer should be thrust through a hole in a lead cover of sufficient size to prevent splashing of the hydrofluoric acid. 

On rare occasions, when pain is not relieved by the narcotic analgesics alone, a mixture of an oral narcotic and other drugp may be used to obtain relief. Brampton s mixture is commonly used to identify these solutions. In addition to the narcotics, such as morphine or methadone, other dragp may be used in the solution, including antidepressants, stimulants, aspirin, acetaminophen, and tranquilizers. The pharmacist prepares the solution according to the primary health care provider s instructions. 

Because molarity is defined in terms of the volume of the solution, not the volume of solvent used to prepare the solution, the volume must be measured after the solutes have been added. The usual way to prepare an aqueous solution of a solid substance of given molarity is to transfer a known mass of the solid into a volumetric flask, dissolve it in a little water, fill the flask up to the mark with water, and then mix the solution thoroughly by tipping the flask end over end (Fig. G.8I. 

The molality of a solute in a solution is the amount (in moles) of solute divided by the mass (in kilograms) of solvent used to prepare the solution. 

To determine the mass of NiCl2 6 H2 O required to prepare the solution, first calculate the number of moles of the salt required, and then use the molar mass to determine the mass in grams ... 

Heats of solution are dependent on concentration. The integral heat of solution at any given concentration is the cumulative heat released, or absorbed, in preparing the solution from pure solvent and solute. The integral heat of solution at infinite dilution is called the standard integral heat of solution. 

Example. A solution of ethyl acetate in pH 10.0 buffer (25°C) 1 hour after preparation was found to contain 3mg/mL. Two hours after preparation, the solution contained 2mg/mL. Calculate the... 

In this step we will be preparing the solution for the alkaloids migration using a common organic non-polar solvent. For our solvent we will use warm naphtha (other solvents are identified in STEP 6.)... 

Dining the preparation of a solution of the aldehyde in dilute sulfuric acid, the latter should be prepared before addition of the aldehyde. An attempt to prepare the solution by adding a slurry of the basic aldehyde in a little water to cone, sulfuric acid caused the stoppered flask to burst from the large exotherm generated by this procedure. 

The cathode is a rolled strip of copper gauze which fits snugly into a 3 X in. test tube and rests on a glass-wool plug which covers a hole of about -in. diameter blown in the bottom of the test tube. During the preparation, the solution about half fills the tube, and the glass-wool plug protects the bulk of the oxidized solution from the cathode. 

Dissolve NHS-PEGg-maleimide (MW 601.6) into DMSO at a concentration of 20mM. Short, PEG-type crosslinkers often exist as a thick oily mass, and preparing the solution typically involves dissolving an entire vial of the compound into DMSO to determine accurately the required concentration. Use only dry DMSO to avoid hydrolysis of the NHS ester. 

Dissolve a purified bait protein in 0.1M sodium phosphate, 0.15M NaCl, pH 7.2, or a similar buffer at neutral pH, which doesn t contain any competing amines (i.e., avoid Tris or Imidazole). The bait protein may be at a concentration of anywhere from O.lmg/ml to lOmg/ml. Prepare the solution in a dark tinted vial or wrap the vessel in foil to prevent light exposure when the crosslinker is added. 

It is convenient to prepare the solution of periodic acid the day before, and then to decant it from some undissolved particles which nearly always remain. A small excess of periodic acid is not detrimental. 

Summarized from Roland and Vian (19). The reader is referred to Chapter 16 and ref. (40) for discussions of ultrastractural cytochemistry. b There is a number of lead citrate formulations. A modification of the Reynold s procedure (60a) is that of Sato (61). Meticulous care must be taken to keep the lead citrate solution free of lead carbonate, which originates via reaction of lead citrate with atmospheric C02. Once prepared, the solution can be stored in capped syringes at 4°C. 

How many grams of sodium chloride should be used in preparing the solution ... 

A gravimetric factor is a number used to convert, by multiplication, the weight of one chemical to the weight of another. Such a conversion can be very useful in an analytical laboratory. For example, if a recipe for a solution of iron calls for 55 g of FeCl3 but a technician finds only iron wire on the chemical shelf, he or she would want to know how much iron metal is equivalent to 55 g of FeCl3 so that he or she could prepare the solution with the iron wire instead and have the same weight of iron in either case. In one formula unit of FeCl3, there is one atom of Fe, so the fraction of iron(III) chloride that is iron metal is calculated as follows ... 

Calculate the mean and standard deviation for each of the data sets. Which method of preparing the solutions results in the least variability ... 

When solutions of this type are prepared, the solute and solvent are weighed out separately and then mixed together to form a solution. The final volume of the solution is unknown. 

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