Solutions volume percent

Analyze the Problem 49 mL of alcohol solute volume percent (v/v) ... 

A stock solution is prepared by weighing out an appropriate portion of a pure solid or by measuring out an appropriate volume of a pure liquid and diluting to a known volume. Exactly how this is done depends on the required concentration units. For example, to prepare a solution with a desired molarity you would weigh out an appropriate mass of the reagent, dissolve it in a portion of solvent, and bring to the desired volume. To prepare a solution where the solute s concentration is given as a volume percent, you would measure out an appropriate volume of solute and add sufficient solvent to obtain the desired total volume. 

Usually, free-radical initiators such as azo compounds or peroxides are used to initiate the polymerization of acrylic monomers. Photochemical (72—74) and radiation-initiated (75) polymerizations are also well known. At a constant temperature, the initial rate of the bulk or solution radical polymerization of acrylic monomers is first order with respect to monomer concentration and one-half order with respect to the initiator concentration. Rate data for polymerization of several common acrylic monomers initiated with 2,2 -azobisisobutyronittile (AIBN) [78-67-1] have been determined and are shown in Table 6. The table also includes heats of polymerization and volume percent shrinkage data. 

GC assay of the organic layer showed no EIN(TMS)2 remaining after 15 min of stirring (GC conditions Restek RTX-1 column (30 m x 0.53 mm, 1 m film thickness), 2.53 mL/min, initial temperature 50°C, final temperature 300°C, rate 20 deg/min, injection temperature 200°C, detector temperature 350°C, injection volume 1 pL, inject sample neat retention times fert-butyl alcohol 1.4 min, THF 1.7 min, heptane 2.1 min, HN(TMS)2 2.6 min, ethylbenzene (present in commercial LHS) 3.1 min, te/ t-butyl acetate 4.0 min). Volume percents were determined based on standard solution counts. 

To explore the feasibility of these polymers as a pendant delivery drug delivery system, 5-fluorouracil activated by 1,1,1,3,3,3-hexamethyl disilazane was coupled to the phosphite via the Todd reaction as shown in Scheme 2. Briefly, the polymer (PPU-7) solution in dimethylacetamide was mixed with a 1 1 v/v solution of carbon tetrachloride and methylene chloride containing 0.5 volume percent of triethylamine (TEA) as catalyst. The activated drug dissolved in methylene chloride was added slowly into the mixture and allowed to react for 48 hours at room temperature. The product was isolated by precipitation into carbon tetrachloride. 

Roberts and Laine [25] describe a process for electrochemically transferring oxygen with the scheme shown as Fig. 11. Air or other oxygen-containing gas is drawn into the left side of the vessel. The solution contains an organic solvent such A-methyl pyrrolidine with a supporting electrolyte as tetrabutyl ammonium tetrafluroborate. The carrier, one of the two Schiflf bases shown as Fig. 12, is dissolved to about 3 volume percent. 

Percentages can be used as factors. The percentage of something is the number of parts of that thing per hundred parts total. Whatever unit(s) is used for the item in question is also used for the total. For example, the percent by mass of water in a solution is the number of grams of water per hundred grams of solution or the number of kilograms of water per 100 kg of solution. The percent by volume of alcohol in a mixed drink is the number of milliliters of alcohol in lOOmL of the drink, and so forth. If the words by volume or some other similar words are not stated, assume percent by mass. 

A To determine mass percent, we need both the mass of ethanol and the mass of solution. From volume percent, we know that 100.0 mL of solution contains 20.0 mL pure ethanol. The density of pure ethanol is 0.789 g/mL. We now can determine the mass of solute (ethanol) and solution. We perform the calculation in one set-up. 

For water, the mass in grams and the volume in mL are about equal the density of water is close to 1.0 g/mL. For ethanol, on the other hand, the density is about 0.8 g/mL. As long as the final solution volume after mixing is close to sum of the volumes for the two pure liquids, the percent by volume of ethanol will have to be larger than its percent by mass. This would not necessarily be true of other ethanol solutions. It would only be true in those cases where the density of the other component is greater than the density of ethanol. 

Percent volume-in-volume (percent by volume), % v/v number of milliliters of a constituent (solute) in 100 mL of preparation (solution)... 

One common way of expressing the relative amount of solute and solvent is through percentage, amount per hundred. There are three ways that we may express this percentage mass percent, mass/volume percent, and volume/volume percent. 

The mass/volume percent of a solution is the mass of the solute (typically in grams) divided by the volume (typically in mL) of the solution and then multiplied by 100% to yield percentage. 

The third case is one in which both the solute and solvent are liquids. The volume percent of the solution is the volume of the solute divided by total volume of the solution and then again multiplied by 100% to generate the percentage. 

Prepare four to six standard solutions of ethanol in water such that the alcohol content of the wine (as indicated on the wine label) is in the middle. For example, if the wine is 15% ethanol (volume percent assumed), standards of 5,10,20, and 25% are appropriate. Use 25-mL volumetric flasks, and pipet the ethanol accurately. Dilute to the mark with water and then add 1.00 mL of acetone (the internal standard) above the mark. Shake well. 

When volume percent solutions are prepared, the mL of the solute are diluted with solvent to the required volume. 

If the solute is ethyl alcohol and the solvent is water, then another concentration term is used, proof. The proof of an aqueous ethyl alcohol solution is twice the volume percent. A 45.0 volume % ethyl alcohol solution would be 90.0 proof. 

A—To calculate the molarity, the moles of urea and the volume of the solution are needed. Density is an intensive property, so any arbitrary volume of solution may be used. One liter is a convenient volume. Using this volume and the density of the solution, you can calculate the mass of the solution. Ten percent of this is the mass of urea. The mass of urea and the molecular weight of urea give the moles of urea. 

Altered thermodynamic activity of proteins in solution arises when unreactive (or inert) macromolecules are added to a solution and occupy more than a few percent of total solution volume. Terms such as unreactive , "background, or inert are used to emphasize that the added protein need not exhibit and direct binding interaction with the protein of interest. Instead, the consequences have more to do with molecular crowding, and approximate theoretical models show that this effect depends on the shapes and sizes of the macromolecules. Thus, biological fluids are anything but ideal or dilute solutions. 

Effects of allelopathic compounds. To compare the sensitivity of shoot and root length to PSRFW, 25 additional compounds were tested at 2 mH as described in the previous section. Hemp sesbania was harvested at 60 h and barnyardgrass at 72 h. These times were chosen in an attempt to maintain sufficient solution volume during the experiment. Root and shoot lengths, fresh and dry total weights, and percent germination were then determined. TFW was used to determine PSRFW. 

Mg(OH)2 can mean 5 g magnesium hydroxide in 100 mL final volume. This is a mass-volume percent solution. 

Clearly, paying attention to units is important when working with concentration. Only by observing which units are attached to a measurement can you determine whether you re working with molarity, with mass percent, or with a mass-mass, mass-volume, or volume-volume percent solution. 

Calculate the molcuity and the mass-volume percent solution obtained by dissolving 102.9 g H3PO4 into 642 mL final volume of solution. Be sure to use proper units. (Hint 642 mL = 0.642 L)... 

Next, calculate the mass-volume percent solution ... 

A common form of ethanol (CH3CH2OH) is 95 wt% this expression means 95 g of ethanol per 100 g of total solution. The remainder is water. Volume percent (vol%) is defined as... 

Note In a volume/volume percent solution, you cannot measure out 95 milliliters of solvent and think that with 5 milliliters of solute it will equal 100 milliliters of solution. This would require the use of a volumetric flask. Adding some liquids together results in a lower volume than predicted because of spaces between molecules. 

For the most part, the label on consumer products does not indicate which of these percent formulas is used. Typically, a volume/volume calculation is used for solutions made from two liquids. Each manufacturer chooses the method of calculating percent that is most suitable for a particular product. An urban legend of yesteryear claimed that the beer in one state had more alcohol than the beer in an adjacent state. The truth was that one state used a weight/volume percent calculation, whereas the other used a volume/volume approach, and the beers were essentially identical in alcohol content. 

Calculate the weight/volume percent solution formed by adding 10 grams of salt (NaCl) to enough water to make 500 milliliters of solution. 

Calculate the volume/volume percent solution formed by combining 25 milliliters of ethanol with enough water to make 200 milliliters of solution. 

Lipinsky dissolved compounds in DMSO at a concentration of 10 xg/ml. Complete dissolution is controlled by eye. One micro liter of this solution is added into a cuvette containing 2.5 ml pH 7 phosphate buffer. Mixing of the system is controlled via an integrated mixing device. The temperature is kept constant between 22 °C-25 °C. Stepwise one micro liter portions are added to the mixing chamber. After each step a equilibrium time of 5 minute is allowed before turbidity is analysed. These steps are repeated up to 14 times covering a range of < 5 xg/ml to > 65 xg/ml. If precipitation occurs the addition of compound is stopped after further two consecutive additions. The volume percent aqueous DMSO does not exceed 0.67%. 

Chemists often express the concentration of an unsaturated solution as the mass of solute dissolved per volume of the solution. This is different from solubility. It is usually expressed as a percent relationship. A mass/volume percent gives the mass of solute dissolved in a volume of solution, expressed as a percent. The mass/volume percent is also referred to as the percent (m/v). 

---