Open bubble pressure

You can observe heterogeneous nucleation easily in carbonated drinks like "fizzy" lemonade. These contain carbon dioxide which is dissolved in the drink under pressure. When a new bottle is opened the pressure on the liquid immediately drops to that of the atmosphere. The liquid becomes supersaturated with gas, and a driving force exists for the gas to come out of solution in the form of bubbles. The materials used for lemonade bottles - glass or plastic - are poor catalysts for the heterogeneous nucleation of gas bubbles and are usually very clean, so you can swallow the drink before it loses its "fizz". But ordinary blackboard chalk (for example), is an excellent former of bubbles. If you drop such a nucleant into a newly opened bottle of carbonated beverage, spectacular heterogeneous nucleation ensues. Perhaps it is better put another way. Chalk makes lemonade fizz up. 

When the bottle is opened, the pressure decreases to 1 atm. As a result, the carbon dioxide gas in the cola bubbles rapidly out of the solution, causing effervescence or fizzing. 

Changing the pressure has no appreciable effect on the solubilities of either solids or liquids in liquids. The solubilities of gases in all solvents increase, however, as the partial pressures of the gases increase (Figure 14-7). Carbonated water is a saturated solution of carbon dioxide in water under pressure. When a can or bottle of a carbonated beverage is opened, the pressure on the surface of the beverage is reduced to atmospheric pressure, and much of the CO2 bubbles out of solution. If the container is left open, the beverage becomes flat because the released CO2 escapes. 

Fig. 5.14. Dependence ot T2 on the relative amount ot Triton X-100 aggregated in micelles obtained by different methods of the dynamic surface tension oscillating jet [93] ( ), maximum bubble pressure [93] (A), [89] ( ), [90] (T), inclined plate [83] ( ) open symbols refer to results of relaxation methods for the bulk phase [166, 167] according to [93].

Small changes in pressure have little effect on the solubilily of solids in liquids or liquids in liquids but have a marked effect on the solubilily of gases in liquids. The solubility of a gas in a liquid is directly proportional to the pressure of that gas above the solution. Thus the amount of a gas dissolved in solution will double if the pressure of that gas over the solution is doubled. For example, carbonated beverages contain dissolved carbon dioxide under pressures greater than atmospheric pressure. When a can of carbonated soda is opened, the pressure is immediately reduced to the atmospheric pressure, and the excess dissolved carbon dioxide bubbles out of the solution. 

Increase the pressure of the microinjector until air bubbles from the micropipette tip appear, indicating that the tip is open. Typical pressure values for good micropipettes, used in our laboratory for nuclear and cytoplasmic injections, are between 2000 and 4000 hPa. Lower values indicate a tip size above 1 //m. For higher pressure values the micropipette is either closed or the risk for clogging during microinjection is rather high. 

The makers of soda pop use pressure (the result of collisions between gaseous molecules and the surfaces around them) to force gaseous carbon dioxide molecules to mix with liquid water molecules. As long as the can of soda is sealed, the carbon dioxide molecules remain mixed with the water molecules, held there by pressure. When the can is opened, the pressure is released and carbon dioxide molecules escape out of the soda mixture (T Figure 1.1). As they do, they create bubbles—the familiar fizz of soda pop. 

FIGURE 13.6 Pop Fizz Acan of soda pop is pressurized with carbon dioxide. When the can is opened, the pressure is released, lowering the solubility of carbon dioxide in the solution and causing it to come out of solution as bubbles. 

The solubility of gases increases with increasing pressure. When a soda can is opened, the pressure is lowered, decreasing the solubility of carbon dioxide. This causes bubbles of carbon dioxide to come out of the solution. 

FIG. 4 A spherical gas bubble submerged in water saturated with gas at the pressure of the gas in the bubble. The equilibrium is stable for a thermodynamically closed bubble but unstable for an open bubble. 

Another experimental example of the use of the drop and bubble shape technique is given in Figure 12.11. The latter shows the dynamic surface tensions of blood serum as measured by the maximum bubble pressure (filled symbols) and drop shape techniques (open symbols). It becomes evident that both methods complement each other perfectly when the data from the MPT2 studies are plotted as a function of /efi- The results impressively demonstrate that during the radiotherapy process the dynamic surface tension parameters return to the normal values (2), i.e. approach those characteristic of healthy females from the respective control group. 

Figure Dynamic surface tension, a, versus the surface age, t of submicellar (curves a and b) and micellar (curves c and d) solutions of SDS in the presence of 0.128 M Nad measured by the maximum bubble pressure method at surfactant concentrations (a) 0.2 mM, (b) 0.4 mM, (c) 1.5 mAf, and (d) 2.0 mM. The solid and open symbols correspond to different runs. (After Ref. 84.)...

The Effect of Pressure The solubility of gases also depends on pressure. The higher the pressure of a gas above a liquid, the more soluble the gas is in the liquid. In a sealed can of soda pop, for example, the carbon dioxide is maintained in solution by a high pressure of carbon dioxide within the can. When the can is opened, this pressure is released and the solubility of carbon dioxide decreases, resulting in bubbling (Figure 12.12 ). 

Foams (or foam solutions) can be prepared from two overall processes termed condensation and dispersion. In condensation (of a gas), foam is generated from a liquid supersaturated with a gas. A beer in a can is a typical example of this. When the can is opened, the pressure is reduced and less gas (carbon dioxide) can be contained in the hquid and therefore comes out as bubbles and produces foam. Heating can... 

Lower the needle into the halocarbon oil at one end of the line of embryos. Gently push the tip of the needle into the side of the 20 x 20-mm coverglass to break off a small portion of the tip. The goal is to create a l-2- im opening. Apply pressure to the needle to force a drop of the GAL4VP16 solution out of the needle and to remove any trapped air bubbles. 

In the test procedure, the point on the sample from which the first bubbles appear marks the place of the largest pore. A further increase in pressure will produce a second stream of bubbles, from the second largest hole, then the third, and so on. Eventually a pressure is reached at which bubbles will appear to come from the entire surface of the element. This pressure is known as the open bubble or boil point, and is a reasonable measure of the mean pore size of the element. This latter figure is to some extent dependent upon the air velocity through the pores, so comparative tests on different materials should be carried out at the same flow rate (air velocity does not affect the value of the initial bubble point). 

A The unopened bottle of soda water is under a high pressure of C02(g). When a similar bottle is opened, the pressure quickly drops and some of the C02(g) is released from solution (bubbles). 

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