water bubbles experimentt

8/2/2019 Water Bubbles Experimentt

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Objective

The objective of this lab is to understand the effects of temperature, concentration and size of particles

on the solubility of two substances.

Experimental Procedures

To demonstrate the effect of these conditions, water and soap were mixed at the following

configurations in different beakers:

Approximately 50ml of soap water at room temperature. Approximately 50ml of soap water at a higher temperature. Approximately 40ml of water and 50ml of soap water at room temperature. Approximately 40ml of water and 50ml of soap water at a higher temperature.

These setups cover basically concentration and temperature effects in solubility and grain growth.

Water-and-soap solutions are stirred up and then are allowed to mix for around an hour to observe the

following characteristics:

Growth of the particles Number of bubbles Temperature and concentration relationship Number of sides in bubbles

Size of bubbles

Radius of curvature Shape of the bubbles Mobility of the boundary


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Fig. 1: Experiment Setup

Data Analysis

The first observation is the difference in concentration between the 90ml and 50ml solution beakers.

The concentration of bubbles is much higher and they last longer in the 50 ml beaker of soap water due

to the reduced quantity of the solvent (water). There is also a tendency of producing more bubbles in

the areas of higher concentration than lower concentration.

From the video, it is verified that the concentration of bubbles increases and tends to last longer at

lower temperatures and smaller radii. It is also discovered that it requires more energy to break smaller

bubbles, so larger bubbles are the first ones to break as the time passes. This can also be deducted from

the Arrhenius equation which said that the rate of solubility depends on the temperature and energy

added in which the collapse of the molecules is high enough to dissolve the bubbles in water.

With regards to the growth and concentration of bubbles with respect to temperature, it is clear that

bubbles start to break faster as the temperature increases; therefore, it is observed that the

concentration of bubbles is higher in the beaker at room temperature after certain period of time.

Similarly, it was clearly seen that the size of the particles is important to determine the concentration of


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the bubbles in water and interfacial energy to break a bubble. This can be confirmed with the following

two forms of the Gibbs-Thomson effect:

Eq. 1

Eq. 2Where is the concentration of bubbles, is the free-energy, is the surface energy, is themolar volume, is the radius of the particles, and T is the temperature.Comparing the experiment with equation 1, it is observed that the concentration of the bubbles is

higher in the beaker with room temperature than that of the increased temperature. This can also be

related to the radius of the bubbles.

From equation 2, we can deduct that the radius of the bubbles has direct effects on the free energy

contained in the bubbles which means that the bubbles with smaller radii has more free energy than the

bubbles with larger radii and that is the reason why the larger bubbles tends to break faster than the

smaller bubbles.

Looking at one of the vessels, the concentration of bubbles is higher in areas close to the walls (Figure

2), which has an effect on the shape of each bubble. For example, bubbles at the center tend to have a

Figure 1. Concentration of bubbles


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circular shape. On the other hand, the ones close to the walls exhibit irregular shapes with more than

two sides. These kinds of shapes are due to the difference in pressure around each bubble which also

affects the number of sides in the bubbles.

From the experiment, it is observed that the high mobility grain boundary tends to disappear and that as

a result the grains sharing the low mobility boundary tend to be dominant with grain growth for grainboundary energy. It is also observed that the low mobility and low energy boundary tends to be

dominant with grain growth. When the grain boundary has low energy and high mobility, the grain

boundary tends to disappear. This experiment indicates that grain growth and the migration rate of the

boundary between each new recrystallizing grain is taken as a representative of its mobility and that the

driving force is the boundary curvature. This experiment goes further in proving the equation of mobility

right which states that

{ }

Where is the effective flux of the bubbles from grain 1 to 2, is the number of bubbles per unitarea, is the number of times per second that a bubble has the energy of( ) to make a jumpfrom grain 1 to grain 2 which is proportional to the boundary curvature.

Fig. 3: Bubbles closer to the wall of the

beaker which have irregular shapes

Fig. 4: Bubbles at the center of the

beaker which have circular shapes


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Conclusion

This experiment is a fundamental proof of what happens in a material during recrystallization. It shows

the effects of temperature and concentration of the composition in the solubility and grain growth of a

material. It also shows what happens during grain growth and how internal energy affects grain growth

and mobility of the boundary. The effects of the radius of curvature, size and shape of atom on themechanical properties of a material was not left out. With these facts, we can conclude that the essence

of thermomechanical processing is to increase the mechanical properties of a material.

References

D. A. Porter, K. E. Easterling: Phase Transformation in Metals and Alloys, Second Edition,Chapman and Hall(1993).

G. Gottstein, L. S. Shvindlerman: Grain Boundary Migration in Metals: Thermodynamics,Kinetics, Applications, CRC Press (1999).

Jotted notes from class.

water bubbles experimentt

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