Laboratory Measurements and Density

Laboratory Measurements and Density Objectives: A. To determine the density of Aluminum (lit. value = 2.7 g/cm3) by determining its mass, and measuring its volume by dimensional analysis and water displacement. We will also examine the % error in our determination based on the literature value. B. To determine the mass and diameter of select ball bearing. Plot graphs of mass vs. diameter, mass vs. surface area, and mass vs. volume. Afterwards use slop of the mass vs. volume graph to determine density. Procedure: 1. A. Weigh an aluminum cylinder on the analytical balance and record its mass to the nearest 0.01 g. • Using a Vernier Caliper, measure and record the height and diameter of the cylinder. • Using proper formula to determine the volume of the cylinder. A cylinder with radius r units and height h units has a volume of V cubic units given by V = πr2h, (r = ½ d). • Calculate density according to d = mass/volume. • Compare your calculated densities with the literature value for the density of Aluminum and determine the % error for each calculation. B. Add water to a graduated cylinder, read the volume (mL), carefully slide the aluminum cylinder into the water in the graduated cylinder and read the volume (mL) again. The difference between the after volume reading and the before volume reading, gives the volume attributed to the aluminum in mL. Calculate the density of the aluminum using the already determined mass and the displacement volume. C. From the known value for the cylinder’s density, which method has the better accuracy? Which method has the better precision? 2. Weigh 4 ball bearing (one at a time) on an analytical balance to the nearest 0.01 g. Record the mass of the bearing in increasing order. • Measure the diameter of each ball bearing using the Vernier Caliper, and record each value. • Calculate and record the surface area of each bearing using the equation (A = 4πr2). • Calculate and record the volume of each bearing using equation (V = 4/3πr3).