Density
PURPOSE:
To give the student a better understanding of the nature of density through manipulation of lab equipment, gathering data and mathematical use of numeric values.
INTRODUCTION:
Density is the relationship between a materials mass and volume:
D = m / V
where mass is measured in grams and volume in milliliters. Typical densities are: : 0.10 g/mL wood : 0.70 g/mL water : 1.00 g/mL plastic : 1.50 g/mL aluminum : 2.70 g/mL iron : 7.86 g/mL lead : 11.34 g/mL
Water has the density of 1.00 g/mL (when pure at 4°C) and any solid placed in it with a density greater than 1.00 g/mL will sink while those solids with less than 1.00 g/mL will float. Large metal boats float in water due to water displacement and is another topic. If you have two liquids that are immiscible (will not mix like oil and water), the less dense liquid will take the top position over the greater density.
4 samples of plastic have been chosen as your unknown solids. They all have different masses, volumes and densities.
A graduated cylinder will serve as a volume measuring device for this lab. If the volume of water contained in this cylinder is noted and, after the addition of an unknown, noted again. The volume of the unknown can be determined by the amount of water displaced by the solid. It measures in mL
A hydrometer jar is provided that contains 5 different immiscible liquids. Each liquid has a different density thus they separate from each other in 5 distinct bands. If a solid is placed in the jar it will sink down to a level where the density of the liquid just below it is greater than its own density.
A common sink is provided to dispense out water for the graduated cylinder. Clicking on its handle will start the water flowing.
An electric balance is provided to take the required masses.
PROCEDURE:
1) Print Blank Data Report. Unknown “A” has been placed on the balance and record its mass. 2) The graduated cylinder is about half full and note its volume.
3) Sample “A” has been dropped into the graduated cylinder and note that water is displaced and the level rises. Subtract the original volume of water from this second reading and record it as the volume of sample “A”.
4) You are finished with sample “A” now it has been into the hydrometer jar found to the right in diagrams below.
5) Repeat this same procedure (1-4) for samples “B”, “C” and “D”.
6) Calculate the density of each of the samples. Determine the range of density that the oil in level 3 has, in the hydrometer.
Plastic A is on the electronic balance. Record the mass of Plastic A on your data sheet. Graduated cylinder has been filled half way.
Plastic A has been placed in the graduated cylinder. Record the difference in volume on your data sheet.
Plastic A has been dropped in the hydrometer.
Plastic B is on the electronic balance. Record the mass on your data sheet. Graduated cylinder has been filled half way.
Plastic B has been placed in the graduated cylinder. Record the difference in volume on your data sheet.
Plastic B has been dropped in the hydrometer.
Plastic C is on the electronic balance. Record the mass of Plastic A on your data sheet. Graduated cylinder has been filled half way.
Plastic C has been placed in the graduated cylinder. Record the difference in volume on your data sheet.
Plastic C has been dropped in the hydrometer.
Plastic D is on the electronic balance. Record the mass of Plastic A on your data sheet. Graduated cylinder has been filled half way.
Plastic D has been placed in the graduated cylinder. Record the difference in volume on your data sheet.
Plastic D has been dropped in the hydrometer.