Class 237
Performed: October 1, 2013
Due: October 7, 2013
Introduction
Purpose: The Determining Density and Specific Gravity lab tests student capabilities of using equipment to measure volume, mass, density, and specific gravity of solids and liquids with accuracy.
Equipment:
Students use the electronic balance to measure the mass of metals, pipettes, and pipettes holding liquids. The user presses the tare button to set the scale back to 0 g, and then places the metal or pipette onto the balance. The result is rounded to two decimal places.
The graduated cylinder is used for measuring volume of a liquid or water displaced by a solid. The students look at lines, at eye level, drawn onto the side of the cylinder to measure the liquid level, significant figures depends on how accurate the marks go.
Pipettes suck up or expel liquids. Students use the pipette to move liquids to a graduated cylinder by squeezing the top of the pipette to cause suction.
Procedures:
Students follow a procedure to ensure the maximum liquid inside the pipette to measure mass. Students squeeze the top, the larger part, of the pipette to suck in the liquid. The student squeezes the pipette upside down for the air bubbles at the top to escape, then without letting go the top, suck in more of the liquid. This is repeated until all air bubbles are removed.
Students follow a water displacement procedure for volume. A fifty milliliter graduated cylinder is filled to any mark, measured by looking at the meniscus, the lowest part, of the water line. The student then takes one of the metals used in the experiment and slides the metal into the cylinder by tilting the graduated cylinder. The meniscus is measured again, before and after results are calculated.
Data Tables
Table 1. Qualitative table.
Sample number and name
Color