Introduction to Lab Equipment and Safety

Theory

When completing labs, one must understand how to use a variety of lab equipment and know proper lab techniques in order to ensure safety and valid results. Some of the lab equipment that may be used on a regular basis include gas burner, electronic balance, spatula, beaker, graduated cylinder, flask, weigh boat/paper, test tubes, funnel, ring stand, filter paper, evaporating dish thermometer, etc. The lab techniques may include massing/weighing, burning, filtering, measuring volumes and temperature, etc. The more serious your attitude towards the use of equipment and lab technique, the safer you and your partner will be and the more likely your results will be accurate and precise (thus, better lab grades!!).

Purpose

To practice using a variety of lab equipment and lab techniques in a safe, skillful, and efficient manner.

Safety

During this lab, safety goggles must be worn at all times. In addition, be certain to tie back any long hair and role up any loose sleeves due to the use of an open fire. Lastly, to ensure total safety and encourage good habits, please wear closed-toed shoes for this lab and all labs.

Procedure

Filtration

1. Fill your 100 mL beaker with 30 mL of water, obtain one piece of filter paper, one funnel, a ring stand, a stirring rod, one metal ring, approximately 5 grams of sand, one 200 mL Erlenmeyer flask , and one water bottle.

2. Set up the filtration apparatus by attaching the o-ring to your ring stand. Then, place the funnel into the o-ring. Finally, place the E. flask underneath the funnel tip (see figure below).

3. To create a filter, fold the filter paper in half. Then, fold the filter paper in half again creating quarters. Open one lip of the quarters to create a cone-shaped cup. Slide the cup into the funnel (see below).

4. To ensure that the filter paper sits in the funnel, wet the sides of the filter paper with the water bottle.

5. In the 100mL beaker with water, add the approximate 5 grams of sand. To do this, use the spatula to scoop out the sand. Gently pour the sand from the spatula into the weigh boat. As you approach the 5.0 number, gently tap on the spatula in order to transfer small amounts of sodium chloride from the spatula into the weigh boat. YOUR GOAL IS TO NOT GO OVER 5.0 grams as you are gently tapping.

6. To filter the sand out of the water, stir the mixture with a stirring rod as you pour the mixture into the funnel with the filter paper. Ensure that the sand is being dumped into the filter and that the water level in the filter paper does not rise above the top edge of the filter paper. Let the water drip through the filter paper into the beaker. The material collected in the beaker is called filtrate.

7. To remove the wet sand that is stuck to the sides of the beaker, turn the beaker upside down and squirt the sides with the water bottle. Once all of the water has moved through the filter paper, remove the filter paper with sand and throw it away.

8. Discard the water and disassemble the apparatus.

Hot Water Bath Apparatus

1. Obtain a gas burner, with a burner tube already attached, a striker, wire gauze, metal ring, and a 250 mL beaker half filled with water.

2. To assemble the hot water bath apparatus, attach the metal ring to the ring stand. Then, place the wire gauze onto the metal ring. Next, place the 250 mL that is half filled with water onto the gauze. Finally, place burner underneath the wire gauze. The distance between the top of the burner and the wire gauze should be approximately 8 –10 cm.

3. Attach the open end of the burner tube to the gas outlet. Be certain that the gas valve is closed (the gas valve will be perpendicular to the gas outlet).

Caution: Be certain that long hair and loose clothing is properly secured.

4. Release gas into the burner by turning the gas valve to the open position (the gas valve will be completely parallel with the gas outlet). You should be able to hear gas being expelled by the gas burner.

5. Hold the striker approximately 5 cm above the opening of the gas burner. Create a spark from the striker.

6. If you are unable to create a flame after five attempts, shut off the gas valve and wait for ten seconds before repeating steps 3 and 4.

7. Once a flame is created, control the height of the flame by adjusting the Gas Flow Control (see Figure 1) at the base of the gas burner AND by adjusting the position of the gas valve. Both methods may be used to control the height of your flame. Your flame should be no taller than 8 cm.

8. To control the color of your flame, adjust the air vents (see Fig. 1). Be certain to obtain a blue flame.

Figure 1

9. Observe the two portions of the flame—outer and inner cone. The inner portion of the flame is the hottest part of a flame.

10. Once the water boils, shut off the gas valve and allow the gas burner to cool before replacing it to its original location. Never leave a flame unattended.

Electronic Balance and Massing/Weighing Solids

1. Obtain a spatula, one weigh boat, and a beaker of sodium chloride (salt).

2. Place the weigh boat onto the electronic scale.

3. Hit the “Tare” button. Be certain that the electronic balance number goes to zero.

4. Mass/weigh out exactly 5.0 grams of sodium chloride. 5. Once you have massed/weighed out 5.0 grams, pour the sodium chloride into the waste beaker. NEVER POUR ANY SOLIDS BACK INTO THE ORIGINAL CONTAINER.

Measuring Temperature

1. Fill your 100 mL beaker 1/2 with cold tap water.

2. Place your thermometer into the beaker. Do not let the thermometer touch the glass of the beaker.

3. Allow the thermometer to remain in the water until the temperature no longer changes.

4. Record the temperature to the 0.1 place.

Measuring Liquids

1. Obtain one 25 mL pipet and dispenser, one 50 mL graduated cylinder, one

100 mL beaker, one 250 mL beaker, and one 200 mL Erlenmeyer flask (see)

2. Fill your 100 mL beaker 3/4 full of water. Using the pipet, transfer exactly 50.0 mL of water from the beaker into the 50 mL graduated cylinder.

3. Record the exact volume of water in the graduated cylinder by reading the bottom of the meniscus (see Figure 3).

Figure 3

4. Pour the water back into the first beaker.

5. Using the pipet, transfer 50.0 mL of water from the beaker into the second beaker.

6. Record the exact volume of water as determined by the measurement markings on the beaker.

7. Pour the water back into the first beaker.

8. Using the pipet, transfer 50.0 mL of water from the beaker into the E. flask.

9. Record the exact volume of water as determined by the measurement markings on the flask.

10. Keep the water and both beakers. Replace E. flask and graduated cylinder.

**Pre-lab: Go to WebAssign and complete assignment

Data/Observations

Make a generic data table with two columns and four rows and record all

quantitative measurements.

Questions

  1. The key to a great gas flame is knowing how to adjust your flame. You can adjust two aspects of your flame: heat(color) and height. How do you adjust the color of the flame? height of the flame?
  2. Which color of flame is the hottest? Which part of the flame is the hottest?
  3. Why should you never leave a gas flame unattended?
  4. Why do you hit the “tare” button on the electronic balance?
  5. Why should you always use either a weigh boat or a piece of weigh paper when massing/weighing solids?
  6. Why don’t you replace unused solid back into the original container?
  7. Which piece of glassware—graduated cylinder, beaker, E. flask—was the best at accurately measuring the volume of water?
  8. What, then, should the beaker and E. flask be used for?
  9. What is a meniscus? What causes a meniscus to occur? What part of the meniscus do you read?
  10. What does filtration allow you to separate?
  11. What is filtrate?
  12. When filtering, why should the level of the liquid never go above the level of the filter paper?
  13. When reading the thermometer (and graduated cylinder), to what numeric place should your measurement be recorded?
  14. Why shouldn’t you let the thermometer touch the glass of the beaker?

References (This lab is adapted from the following sources)

Holt ChemFile Lab Program, Experiment B1, pg. 1