Density of Liquids and Solids Experiment 1

Objectives To observe the relative densities of some common liquids and solids To determine the densities of water, an unknown liquid and an unknown rectangular solid To determine the thickness of a piece of aluminum foil using the density concept To gain proficiency in pipetting, weighing by difference and determining a volume by displacement

Density: Getting the Mass Physical Property d = m / V To determine density we need to measure mass m and the volume V We normally measure the mass of our unknown indirectly by a technique called weighing by difference. First weigh empty flask or beaker to get m1 Then weigh the same flask with some amount of your unknown in it to get m2 The mass of your unknown munk = m2 – m1 m1 = 101.0120 g m2 = 204.3242 g

Density: Getting the Volume: Solids Then to get the density we need to measure the volume We can get the volume Vunk of an insoluble irregularly shaped solid using volume by displacement Vunk = V2 – V1 = 266 mL – 195 mL = 71mL V2 = 266 mL V1 = 195 mL

Density: Getting the Volume: Liquid Best to use a pipette Or burette

Volume of Rectangular Solid Measure, length L, width W, and height H

Calculating the Density Density of a Liquid 10.0mL of a liquid pipetted into a flask, the mass of the liquid (weighing by difference) 10.141g Density of a Rubber Stopper Stopper mass = 8.453g, displaces 6.5mL of water in a graduated cylinder

Today Measure density of water with 10mL pipette and 125 mL Erlenmeyer Flask (2 Trials) Measure density of an unknown liquid with 10mL pipette and 125 mL Erlenmeyer Flask (2 Trials) Density of a #2 Rubber Stopper – (water displacement with 100mL Cylinder – 2 Trials) Density of rectangular solid Thickness of a piece of rectangular Aluminum foil by measuring its mass and assuming it has a density of 2.70 g/cm3