- Level: International Baccalaureate
- Subject: Chemistry
- Word count: 1517
Water Lab
Extracts from this document...
Introduction
Water Lab - Trial I Aim To investigation the property of surface tension of water. Problem Statement What is the effect of increasing the number of pennies added to a completely filled beaker of water on the surface tension of the water? Hypothesis Materials 25 mL graduated cylinder (Uncertainty � 0.5 mL) 50 mL beakers (Uncertainty � 1 mL) Ruler (Uncertainty � 0.5 mm) Thirty pennies Marble Water Variables Manipulated Variable The volume of pennies added to beaker of water. Responding Variable Whether the water in the beaker overflows (surface tension is lost). Controlled Variables Volume of water in the beaker (The 50 mL beaker will always be filled to the brim so that the water level will be 1 mm over the brim of the beaker). The temperature of the lab (The temperature was kept at a constant 25�C). The volume of one penny (This value will be determined in the experiment). How the variables were controlled. Manipulated Variable The pennies were added one at a time in order to manipulate this variable at a constant rate; increasing the pennies one at a time made it easier to determine exactly how many pennies it took for the beaker to overflow. Controlled Variables [Volume of water in the beaker] The beaker was filled 1 mm above the brim every time to keep the volume of water in the beaker constant, thus allowing for the same strength of surface tension. ...read more.
Middle
50mL, water level is 1mm above beaker's brim 14 3 Slightly over 50mL, water level is 1mm above beaker's brim 15 Results from displacement experiment Volumes of Water, Five Pennies and Water, and Five Pennies in a Graduated Cylinder Volume of water in graduated cylinder (�0.5mL) Volume of five pennies and water in graduated cylinder (�0.5mL) Volume of five pennies in graduated cylinder (�1.0mL) 10 mL 12 mL 2 mL Finding the volume of 5 pennies was calculated Volume of 5 Pennies = Volume of 5 Pennies and Water - Volume of Water = 12 mL (�0.5mL) - 10 mL (�0.5mL) = 2 mL (�1.0mL) Finding the volume of 1 penny To find the volume of 1 penny, divide the volume of 5 pennies by 5. Data Processing To find the volume of pennies required to make the beaker overflow, multiply the volume of one penny by the number of pennies required to make the beaker overflow. Sample Calculation - Trial Processing the data into a table Volume of Pennies Required Causing a Beaker Filled With a Specific Amount of Water to Overflow Trial Volume of water in beaker (�1 mL) Volume of pennies required to make the beaker overflow (�0.2mL) 1 Slightly over 50mL, water level is 1mm above beaker's brim 5.2 mL 2 Slightly over 50mL, water level is 1mm above beaker's brim 5.6 mL 3 Slightly over 50mL, water level is 1mm above beaker's brim 6.0 mL Average of the number of pennies required to make the ...read more.
Conclusion
Although the pins were of the same brand and material, it is not certain that each pin was exactly 0.03g. This uncertainty could result in a change in the overall calculation of the mass. Under time constraints, we could not weigh the pins before putting them on the surface of the water. However, if there was more time allowed, we would have weighed each pin to make sure that each pin is the right mass. Also, while putting the pins on the surface of the water, they tend to move towards the edge of the petri dish, making it harder for the pins to be placed onto the water. As a result of this, some pins were stacked on top of each other, which could result in a concentrated amount of mass in one area of the petri dish that could break the surface tension. One way to improve this could be to find a larger container in which we could conduct the experiment. This way, we have more room to put the pins in, and they would not be accumulating in one specific place. In addition, the temperature of the room in which we conducted the experiment might not have stayed constant. Therefore, there may have been a change in the attractive forces of the molecules, causing a decrease or increase in the amount of weight the "skin" is able to hold. In future experiments, we could use a thermometer in order to monitor the temperature more sufficiently. ...read more.
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