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Chemistry HL Design prac

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Introduction

Year 11 HL Chemistry - 2009 Chemistry Design Prac. By: Jason Chau Investigate one chemistry related factor on the deflection of the liquid flow in the presence of a charged rod Research question How will the amount of time spent rubbing a glass rod affect the angle of deflection of flowing water in the presence of the charged glass rod? Background Research Static electricity is formed in contact with two objects, where one object gains electrons from another, resulting in one object having a positive charge while the other having a negative charge. Some materials tend to lose or gain electrons during contact with other objects. Materials with electrons bonded to it weakly, tend to lose electrons while materials with fewer electrons on the outer shell tend to gain electrons. Therefore, when an object is imbalanced of a positive or negative charge, it has static electricity. Polarity is the separation of electric charges, caused when electrons are not equally shared in a molecule. This is caused when some atoms in the molecule have a higher electronegativity than others, causing more electrons to be attracted to it, leaving one side of the molecule more negative than the other. ...read more.

Middle

The glass rod The same glass rod with a diameter of 1cm will be used throughout the experiment. Pressure when rubbing the glass rod Use the same person to rub the glass rod against the silk, applying the same pressure every time. Placement of the glass rod A line will be marked on the grid paper so the glass rod will be placed at the exact point and the exact angle to the flowing water every time. Placement of the grid paper The grid paper will be sticky taped to the burette and placed as close as possible to the flowing water. The same grid paper will be used and left at the same position throughout the experiment. Weather conditions The experiment will be conducted in a room with all windows closed and air conditioning switched off to reduce effects atmospheric effects on the angle of deflection of the water. Stopwatch The one person will be using the same stopwatch every time to reduce systematic errors. Material The same piece of silk cloth (20 cm in length, 15cm in width) ...read more.

Conclusion

Repeat the experiment from steps 6 - 10, changing the time rubbing the glass rod against the silk cloth by 20, 30, 40, 50 and 60 seconds. 13. Remove the grid paper and line up all the points of the deflected water to the origin 14. Measure the angles with a protractor and record the results into the table below 15. Pack up the experiment Table 2 - Raw data table Time charging the glass rod Angle of deflection of water Trial 1 Trial 2 Trial 3 Trial 4 Trial 5 Trial 6 Average 10 seconds 20 seconds 30 seconds 40 seconds 50 seconds 60 seconds Table 3 - Risks involved in the experiment and safety precautions to reduce the risks Risk Safety Precaution Action to take The burette is very long and is made of glass and can be broken easily Hold the burette with two hands and always watch for obstacles when carrying around the lab. Wear closed in shoes, lab coat and safety glasses in case the burette breaks. Carefully pick up the large pieces of broken glass one by one and throw in the glass bin. Use a brush to sweep all the small bits into the bin. Make sure there is no remaining broken glass in the lab. ...read more.

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