Density and Measurement
Objectives:
o Learn how to weigh objects with the analytical balance.
o Learn how to measure volumes by various methods.
o Determine the density of several substances.
o Learn how to determine errors in measured (mass, volume) and calculated (density) quantities.
Procedure: Part 1: Weighing with the Electronic Analytical Balance
o Weighing by difference with the Electronic Analytical Balance using tongs to handle items. (Weigh a clean dry 150 ml beaker on the analytical balance (mg); place metal test tube holder in the beaker and weigh again (mg). Repeat on two different analytical balances; calculate the mass of the test tube holder in each trial; calculate the average mass from the three trials; calculate standard deviation.
Part 2: Density of Various Solids
o Density of Glass; measure the mass of the marbles; weigh and record the mass of a clean dry 150 ml beaker; add 5/6 marbles to the beaker, reweigh on the same balance. Measure the volume of the marbles, add 25-30 ml of water to a 50 ml graduated cylinder and record precisely. Compute the density of the glass marbles then the average radius (determine the average volume of a single marble before the average radius of the marbles, divide the total volume of the marbles by the number used to get the average volume of a marble).
o Density of a Metal: Wipe the metal clean with a tissue, weigh it on the analytical balance; measure the volume of the metal: measure the dimensions of a piece of metal in cm and calculate the volume; calculate the density of the metal. Measure the volume of the metal by measuring the displacement of water in the graduated cylinder then calculate the density. Try to identify the metal.
Part 3: Density of Water and Use of a Buret
o Fill 25ml buret with tap water using funnel, open the stopcock and drain the water into a beaker. Practice delivering precisely 10.00ml, 1.00ml, 1 drop at a time, half drop. Fill 100 or 150ml beaker with about 75mml...