Lab 1: Procedures

Lab 1 - PROCEDURE A. Length Measurement 1. Measure the length of a 13 x 100 mm test tube with each of the following: (a) METRIC RULER A, and (b) METRIC RULER B. If you are having problems measuring the test tube, get out a sheet of note book paper. Lay the test tube on the paper and using a pen or pencil, draw an outline of the test tube. Be sure you get as close to the glass as you can with the lead or ball tip of the pen so you’re not creating a space margin with the writing instrument. Measure the outline with the ruler. Note: Refer to METRIC RULER A instructions in Example Exercise 2.1. Refer to METRIC RULER B instructions in Example Exercise 2.2. 2. Measure the diameter of a watch glass with each of the following: (a) METRIC RULER A, and (b) METRIC RULER B. If you are having problems with the watch glass moving around, lay it upside down with the wide open mouth on the note book paper. Draw an outline as you did with the test tube, making sure to get the pencil lead or ball pen tip against the glass edge. Measure your outline. Note: Refer to METRIC RULER A instructions in Example Exercise 2.1. Refer to METRIC RULER B instructions in Example Exercise 2.2. 3. Measure the diameter of an evaporating dish (not the spout) with each of the following: (a) METRIC RULER A, and (b) METRIC RULER B. If you are having problems with the evaporating dish moving around, lay it upside down with the wide open mouth on the note book paper. Draw an outline as you did with the test tube, making sure to get the pencil lead or ball pen tip against the ceramic edge. Measure your outline where the opposite sides are away from the spout. Note: Refer to METRIC RULER A instructions in Example Exercise 2.1. Refer to METRIC RULER B instructions in Example Exercise 2.2. B. Mass Measurement Before you get started, make sure the balanced is zeroed out. First, clean off the balancing surface with the provided brush, or gently brush the surface off with dry paper towel. Do not press down on the balance; you could damage the weighing mechanism. Next, press the zero button and wait for the balance to go to the ready position. There should be an indicator displayed on the digital read out that indicates it’s at zero. Now you’re ready to weight your objects. 1. Determine the mass of an empty 250-mL beaker on each of the following balances: (a) Decigram balance (b) Centigram balance (c) Milligram balance. 2. Determine the mass of an empty 125-mL Erlenmeyer flask on each of the following balances: (a) Decigram balance (b) Centigram balance (c) Milligram balance. 3. Determine the mass of an empty crucible and cover on each of the following balances: (a) Decigram balance (b) Centigram balance (c) Milligram balance. Note: Refer to balance instructions in Appendices B, C, and D. C. Volume Measurement 1. Fill a 1 00-mL graduated cylinder with water. Adjust the bottom of the lens to the full mark with a dropper pipet. Record the volume as 100.0 mL. 2. Fill a 13 x 100 mm test tube with water from the graduated cylinder. Record the new volume in the graduated cylinder (± 0.5 mL). Note: Refer to the graduated cylinder instructions in Figure 2.1. 3. Fill a second test tube with water. Record the volume in the graduated cylinder. D. Temperature Measurement 1. Record the temperature in the laboratory using a Celsius thermometer (± 0.5°C). This is the average air temperature at your lab table. 2. Half fill a 100-mL beaker with ice and water. Hold the thermometer in the ice water, and record the coldest observed temperature (± 0.5°C). 3. Half fill a 150-mL beaker with cold tap water. Place the beaker, level, on the electric hot plate and turn it on. For the water to boil, turn the temperature knob about 100 degrees Celsius. For the best results, turn the temperature to about 150 or 200 degrees. Heat the water to boiling and shut off the hot plate. Hold the thermometer in the boiling water and record the hottest temperature (± 0.5°C). Do not let the thermometer touch the bottom of the beaker; it will change your results. Be sure you use safety equipment for this experiment. If you move the beaker of hot water, wear a blue hot glove. Note: Refer to the laboratory hot plate instructions in Appendix A. You should not let the tip of the thermometer touch the bottom of the glass beaker. Do not place the hot beaker on the cold lab tables, the glass will break and the hot liquid will flow freely and injure someone. Leave the beaker on the hot plate with the heater turned off until you’re ready to pour the water down the drain. While moving the beaker to the sink, be aware of who else is around you and do not drop hot water on your class mates. Figure 2.4 Temperature of Boiling Water To avoid breakage, do not allow the thermometer to touch the hot glass beaker. E. Mass and Volume of an Unknown Solid 1. Obtain a rectangular solid, and record the unknown number in the Data Table. Find the mass of the unknown rectangular solid using each of the following: (a) Decigram balance (b) Centigram balance (c) Milligram balance. 2. Measure the length, width, and thickness of the rectangular solid unknown using METRIC RULER A in Figure 2.3. Calculate the volume. 3. Measure the length, width, and thickness of the rectangular solid unknown using METRIC RULER B in Figure 2.3. Calculate the volume.