Investigation 4.2: Factors Affecting Viscosity Question How does changing the temperature (°C) of glycerin affect the viscosity s -1 of glycerin (l), when tested by dropping a marble from a constant height into the glycerin (l) and timed with a stopwatch until the marble hits the bottom? Design Independent Variable: The independent variable of this experiment is the temperature (°C) of the glycerin (l). Dependent Variable: The dependent variable of this experiment is the viscosity s -1 of the glycerin (l). Controlled Variable(s): The controlled variable(s) are: the liquid used, the marble used, the distance the marble is dropped, the volume (mL) of glycerin in the graduated cylinder. The liquid used is glycerin. The same marble is used throughout the experiment, and it has a mass of 4.61g±0.01g. The distance the marble is dropped is 24.70 ±0.05cm. The amount of glycerin in the graduated cylinder is kept at a constant 50±0.5mL. *Note: Glycerol and Glycerin are the same, and the nomenclature is interchangeable
1 x pebble-shaped marble with a radius of 0.70±0.05cm 1 x ruler 7 x frozen ice packs 1 x plastic bin 1 x stopwatch±0.1s 1L glycerin 5 x thermometers ± 0.5°C 1 x safety goggles 1 x retort stand 1 x thermometer clamp 5 x 100mL plastic graduated cylinder ±0.5 mL (23.70±0.05cm in length) 1 x hot water bath with temperature knob 1L distilled water 1 x 400mL±5% glass beaker 2 x 500mL±5% glass beaker 1 roll of tape Ball-point pen Stirring Rod
Procedure 1. Put on safety goggles. 2. Fill 2, 500mL beakers fully with the 1L glycerol. 3. Put a piece of tape on each 100mL graduated cylinder, and using the pen, label ‘10°C,20°C,30°C,40°C and 50°C’, respectively Procedure for 20° condition
1. Pour 50mL of glycerin from one of the 500mL beakers into the graduated cylinder labeled ‘20°C’ 2. Take the thermometer and place it in the ‘20°C’ graduated cylinder, ensuring bottom of the thermometer touches only the glycerin. Hold position for 1.5 minutes. Record this value under the ‘actual temperature’ column in Table 1 3. Record any qualitative data 4. Take the pebble-shaped marble, and hold it over the opening of the graduated cylinder. Use a ruler to make sure the base of the marble is 1..±0.05cm above the opening of the graduated cylinder. 5. Simultaneously release the pebble and start the stopwatch. When the marble hits the bottom of the graduated cylinder is when the timer should be stopped. 6. Record time taken for marble to reach the bottom (in seconds) in Table 1. Also record any qualitative observations 7. Using a stirring rod, remove the marble from the graduated cylinder. 8. Repeat steps 4-7 for two more trials.
Procedure for 30°,40° and 50° conditions
1. 2. 3. 4.
5. 6. 7.
9. 10. 11. 12.
Transfer 200 mL of glycerine from 500mL beaker to 400mL beaker Attach one thermometer to thermometer clamp, and attach that to a retort stand Place 400 mL beaker in hot water bath Place thermometer apparatus beside hot water bath, and place the thermometer inside the beaker full of glycerin. Turn on hot water bath, setting the level on the knob at 7. Wait for temperature to rise to 50° When temperature is at 50°, remove beaker from the water bath, and pour 50mL of glycerin into the graduated cylinder labeled ‘50°’. Note the temperature given by the thermometer in the Actual Temperature column in Table 1 Take the pebble-shaped marble, and hold it over the opening of the graduated cylinder. Use a ruler to make sure the base of the marble is 1..±0.05cm above the opening of the graduated cylinder. Simultaneously release the pebble and start the stopwatch. When the marble hits the bottom of the graduated cylinder is when the timer should be stopped. Record time taken for marble to reach the bottom (in seconds) in Table 1. Also record any qualitative observations Using a stirring rod, remove the marble from the graduated cylinder. Repeat steps 8-11 for two more trials....
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