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Transcript of Investigatory Project
Jenny Velandria The Effect of Salt and
Temperature on the Surface
Tension of Water Statement of the Problem and Objectives Problem: How can the salinity and temperature of water affect its condition and surface tension?
Our group aims:
1.To compare the strength and cohesiveness of surface tension in pure water and salt water
2.To identify if rising temperature of water increases or decreases surface tension 3.To identify if adding solute would increase or decrease surface tension
4.To determine the combination of factors where the surface tension is strongest or weakest
5.To further explain the result of forces arising from surface tension resulting to flotation of objects Significance of the Project Water and other fluids also have the ability to form into a spherical shape which is possible through the effects of surface tension. Surface tension of water is caused by the cohesive forces between molecules in a liquid which are shared by all neighboring molecules. It is a condition when the surface of water that is in contact with air acts like a thin elastic sheet. The basis for the strength of the surface tension depends on the hydrogen bonds present and thus, behaving as though the surface is coated with an invisible film or membrane instead of overflowing. Surface tension is also essential in the transferring of energy from wind to water. Surface tension also defines the physical characteristics of certain amounts of liquids. We chose this project because we want to give importance to surface tension which seems insignificant but in fact without it, we will not be able to look at life the way it is right now. Surface tension also allows the movement of blood through tiny vessels in the bodies of some animals and enables them to live. some insects, like water striders depend on surface tension to be able to eat and move. The life of a plant also depends on surface tension which allows the water and nutrients to travel to its roots and stems for it to survive. Many researchers say that some additives and temperature could affect the surface tension of a substance, specifically water. Through this, we will be able to determine the strongest surface tension with the right temperature and exact amount of additives. Surface Tension is also needed in inkjet printers. Inkjet printers are vital in business and work: if the surface tension of ink is too high, the ink may clog the nozzle thus making it unable to print important documents. If surface tension is too low, it can cause the ink to leak and bleed on the paper. This study will verify that the strength of surface tension would greatly affect and improve our way of living and our surroundings. It will also show that surface tension is not an insignificant property of water but rather a property that concerns all. Materials and Methods Materials and Equipment 2 beakers
400ml distilled water
A measurement cylinder
2, 3 & 4 tablespoons of salt (in each temperature)
A cup of rice grains
2 pieces of aluminum foil measuring 1cm x 1cm each
A hot plate Data and Results The attraction of the molecules of pure water aided the flotation of more rice grains. We repeated the procedure and saw the pattern of the result still with the number of rice grains increasing as the temperature decreases. The surface of pure water with a lower temperature is the combination that can support the highest amount of rice grains. Procedure 1. The independent variable is the salinity of the water and its temperature – 15°C, 25°C, 35°C, 45°C and 55°C. The dependent variable is the weight exerted on the aluminum foil before it sinks. This is determined by gradually adding grains of rice on the surface of the aluminum foil. The constants (control variables) are the size of the aluminum foil, the size of the grains of rice and the room temperature. 15°C 25°C 2. The 2 beakers are labeled “pure water” and “salt water”. The beakers are each filled with 200 ml of distilled water. In the beaker labeled “salt water” 2 tablespoons of salt are added and mixed into the water. The 2 beakers are placed in the refrigerator until the contents in the 2 cups reach 15°C. The beakers are taken out of the refrigerator and the required temperature confirmed using a thermometer. 3. The 1cm x 1cm piece of aluminum foil is made to float on the surface of the water in the beaker labeled “pure water”. The grains of rice are placed one at a time on the aluminum foil until the aluminum foil sinks into the water. The number of rice grains placed on the foil is recorded. 35°C 45°C 55°C 4.Procedure 3 is repeated with the beaker labeled “salt water” and the results recorded in the table below.
5. The 2 beakers are brought to a room temperature of 25°C and Procedure 3 is repeated on these 2 beakers. The results recorded in the table below.
6. The 2 beakers are then placed on a hot plate and heated to temperatures 35°C, 45°C and 55°C. Procedures 3 and 4 are repeated at each required temperature level and the results recorded in the table below. Analysis of Data salt water “breaks” the surface tension. This then weakens the surface tension, allowing the foil to carry a lesser amount of rice This then weakens the surface tension, allowing the foil to carry a lesser amount of rice grains. we found out that surface tension is stronger when the temperature decreases. the number of rice grains increase as the temperature decreases. salt decreases the temperature of water Conclusion Pure water is more cohesive than salt water because the water molecules of pure water attract one another and are more bonded since there are no other substances added to it which leads to a greater and stronger surface tension. The higher the temperature was, the weaker the surface tension got because the water molecules expand which weakens the bond between the molecules and diminishes the surface tension. Surface tension is at its greatest when the temperature is lower and when cohesion between water molecules is strong. And is at its weakest when the temperature is higher and cohesion between water molecules is weak. This transferring of energy creates waves that are necessary for the rapid oxygen diffusion in bodies of water. Plants are also able to thrive because surface tension allows the transportation of water and dissolved nutrients from the roots through the different parts of the plant. We know that in a way this study can help the community because through this we will be able to determine the combination of the factors in water, its salinity and temperature in particular, that will be able to produce the strongest surface tension. These processes are the development, formulation and manufacturing of drugs and cleaning products. 7. Repeat the entire procedure for the beaker labeled “salt water” but this time, a tablespoon of salt is added so that it would already contain 3 tablespoons of salt. Do the same procedure in adding another tablespoon so that it would contain 4 tablespoons of salt. Recommendations If you would like to try doing this project, we highly recommend you the following:
Use tweezers as you place the rice grains on the aluminum foil so that it would be easier to control
Use a thermometer that could measure up to 0 degrees Celsius in order to attain the desired temperature Fold walls on the side of the aluminum foil to accommodate more rice grains but still the area of the foil in contact with the water should be 1x1 cm
Use iodized salt so that it would easily dissolve in water
Use even pieces of rice grains for accuracy