Ib Chemistry Lab Sl

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

Materials                  

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